Module 9 Human Factors 3a362g

EASA PART 66 CATEGORY B1.1

MODULE 9 - HUMAN FACTORS

TRAINING NOTES

TECHNICAL TRAINING CENTRE HELITOURS PRIVATE LIMITED

TECHNICAL TRAINING CENTRE

EASA 66 CATEGORY B1.1 MODULE 9 HUMAN FACTORS

FOR TRAINING PURPOSES ONLY The training note and diagrams are compiled by Helitours Technical Training and although comprehensive in detail, they are intended for use only with a Course of instruction. When compiled, they are as up to date as possible, and amendments to the training notes and diagrams will NOT be issued.

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For Training Purposes Only

Issue date/Rev Initial



MODULE 9

HUMAN FACTORS

SUB MODULE 9.1

GENERAL / INTRODUCTION TO HUMAN FACTORS

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CONTENTS

Introduction ......................................................................................

1-1

Human Factors Definitions ...............................................................

1-2

NEED TO ADDRESS HUMAN FACTORS ..............................................

1-3

What is “Human Factors”? ...............................................................

1-4

Origins of Human Factors .................................................................

1-6

Statistics............................................................................................

1-16

Incidents and Accidents Attributable To Human Factors / Human Error 1-16 Incidents ...........................................................................................

1-17

Portland Oregon ...............................................................................

1-18

Kegworth ...........................................................................................

1-18

Cockpit Resource Management (CRM) .............................................

1-20

The convertible 737 ..........................................................................

1-21

CCC  HPIM  MRM ......................................................................

1-22

Incidents and Accidents - A Breakdown in Human Factors ..............

1-27

Murphy’s Law....................................................................................

1-28

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GENERAL / INTRODUCTION TO HUMAN FACTORS INTRODUCTION An understanding of the importance of human factors to aircraft maintenance engineering is essential to anyone considering a career in aircraft maintenance. Human factors impinges on everything maintenance personnel do in the course of their job in one way or another, from communicating effectively with colleagues to ensuring they have adequate lighting to carry out their tasks. Knowledge of this subject has a significant impact on the safety standards expected of the aircraft maintenance personnel. Whilst this text has been prepared for those who are working in aircraft maintenance engineering environment, it is also relevant to all staff who are wishing to qualify as certifying staff under EASA Part 66. Thus whilst the term ‘engineer’ has been used throughout the document, it is generally used in a generic sense to include all aircraft maintenance technicians, fitters, licensed engineers, inspectors and supervisors and in some cases, it also includes managers, planners, etc. Human Factors and Error Management is a combination of common sense and proven scientific knowledge about the way daily work is done. The information received in this course centres around the actions and inactions of the individual in the work place and considers systems that are designed to discover and correct errors before they have any negative impact on safety. The principles associated with this subject area reflect the facts that as human errors are subjected to be made. If it is accepted that errors are subjected to be made, then a policy of zero error tolerance is unlikely to be an effective safeguard against any errors eventually having harmful effects on operations. Therefore, a policy of error management is much more likely to result in safe operations. This subject, then, is concerned about recognizing the variety of factors that affect humans, both positively and negatively, when daily work are done and about picking up any errors that might be made and managing them such that both the frequency and impact of incidents and accidents in the workplace are reduced. Aircraft maintenance is an essential component of the aviation system which s the global aviation industry. As air traffic grows and the stringent requirements of commercial schedules impose increased demands upon aircraft utilization, the pressures on maintenance operations for on-time performance will also continue to escalate. This will open further windows of opportunity for human error and subsequent breakdowns in the system's safety net. There is no question that human error in aircraft maintenance has been a causal factor in several air carrier accidents. It is also beyond question that unless the aviation industry learns from these occurrences, maintenance-related safety breakdowns will continue to occur. From a Human Factors perspective, important truths have been uncovered during the investigation of these occurrences.

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HUMAN FACTORS DEFINITIONS Human Factors is an evolving subject and no single definition seems to meet all of the needs of industry. Considering a number of definitions that have been proposed though, a common thread of what is the essence of Human Factors begins to show through. Elwyn Edwards (1988) suggested that Human Factors (or Ergonomics) may be defined as the technology concerned to optimize the relationships between people and their activities by the systematic application of the human sciences, integrated within the framework of systems engineering. McCormick and Sanders (1983) have attempted to define Human Factors more generically by means of suggesting a set of three interrelated dimensions, with the following labels: focus, objectives and approach of Human Factors.  Focus relate to the: (1) design and creation of human-made objects, products, equipment, facilities and environments that people use; (2) the development of procedures for carrying out tasks and work; (3) the provision of services to people; and (4) the evaluation of the things people use in of their suitability for people.  The objectives of human factors relates to two functions: (1) enhancing the effectiveness and efficiency with which work and other activities is carried out by people; (2) maintaining and enhancing certain desirable human values such as safety, health, aesthetic value, etc.

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 The main approach of human factors is the systematic application of relevant information about human abilities, characteristics, behaviour (psycho-social), motivation and communication patterns in the execution of work and social interactions. All of these definitions provide for a good understanding of the essence of human factors which sums up the entire subject matter. It is enough to say that attempts to cover all aspects of human factors within one or two sentences are very difficult or extremely long. The FAA Guide provides the following statements which are relevant to defining the subject: Human Factors is the study of the human as a central part of any system. Human Factors identifies the capabilities and limitations of human and, then, adapts the human or the system components accordingly. The science Human Factors can quantify human performance with measures like time, units of work, safety, error, and sometimes, attitudinal change. Such measures help to design or modify systems for optimal human performance. Therefore, operational attention to Human Factors can raise efficiency, effectiveness, and safety in aviation environments. That translates to cost control and continuing safety.

9.1.1 NEED TO ADDRESS HUMAN FACTORS In the early days of powered flight, the design, construction and control of aircraft predominated. The main attributes of the first pilots were courage and the mastery of a whole new set of skills in the struggle to control the new flying machines. As the technical aspects of flight were overcome bit by bit, the role of the people associated with aircraft began to come to the fore. Pilots were ed initially with mechanisms to help them stabilize the aircraft, and later with automated systems to assist the crew with tasks such as navigation and communication. With such interventions to complement the abilities of pilots, aviation human factors were born. As stated in the Introduction, an understanding of the importance of human factors to aircraft maintenance engineering is essential to anyone considering a career as a licensed aircraft engineer. This is because human factors will impinge on everything they do in the course of their job in one way or another.

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WHAT IS “HUMAN FACTORS”? The term “human factors” is used in many different ways in the aviation industry. The term is, perhaps, best known in the context of aircraft cockpit design and Crew Resource Management (CRM). However, those activities constitute only a small percentage of aviation-related human factors, as broadly speaking it concerns any consideration of human involvement in aviation. The use of the term “human factors” in the context of the Aloha aircraft in the USA in 1988 and the BAC 1-11 windscreen accident in the UK in June 1990 brought the need to address human factors issues in this environment into sharp focus. This does not imply that human factors issues were not present before these dates nor that human error did not contribute to other incidents; merely that it took an accident to draw attention to human factors problems and potential solutions. Before discussing how these accidents were related to human factors, a definition of human factors is required. There are many definitions available. Some authors refer to the subject as ‘human factors’ and some as ‘ergonomics’. Some see “human factors” as a scientific discipline and others regard it as a more general part of the human contribution to system safety. Although there are simple definitions of human factors such as: “Fitting the man to the job and the job to the man”, a good definition in the context of aviation maintenance would be: "Human factors" refers to the study of human capabilities and limitations in the workplace. Human factors researchers study system performance. That is, they study the interaction of maintenance personnel, the equipment they use, the written and verbal procedures and rules they follow, and the environmental conditions of any system. The aim of human factors is to optimize the relationship between maintenance personnel and systems with a view to improving safety, efficiency and well-being”.

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Thus, human factors include such attributes as:  human physiology  psychology (including perception, cognition, memory, social interaction, error, etc.)  work place design  environmental conditions  anthropometrics (the scientific study of measurements of the human body) SUBSET DEFINITIONS Ergonomics - The study of work Anthropometrics – The science of measurement and the art of application that establishes the physical geometry, mass properties, and strength capabilities of the human body The study of Anthropometrics (human measurement) is concerned with the physical sizes and shapes of humans. Of particular interest are the differences between and among different populations (men vs. women, Northern Europeans vs. Japanese). Anthropometrics literally means man (anthro) measurements (metric). It is the measurement of the size and proportions of the human body, as well as parameters such as reach and visual range capabilities. Accurate data on height, weight, limb, and body segment sizes are needed to design items ranging from clothing, furniture, automobiles, buses, and subway cars to space shuttles and space stations. Anthropometrics enables us to properly size items, including system interfaces, to "fit" the . Biomechanics – Addresses issues of movement, leverage, and strength. Biomechanics (bio=life + machine) is the application of the principles of mechanics and physics to measure the forces exerted by and upon living forms. Human Factors is principally concerned with occupational biomechanics which is the application of these principles to the measurement of forces exerted by and upon the human body during the performance of work. These measurements are used to determine physical work performance tolerances with the goal of maximizing work performance while protecting worker occupational health and safety. The application of the principles of mechanics and lever systems to the human body requires the use of anthropometric data, critical data being the distance/length of body levers (bones) between ts. Human variability in physical size (static anthropometry) and physical strength (dynamic anthropometry) is also important in biomechanics with respect to the worker population in of gender, age, and ethnicity. Above is an example of biomechanical calculations of the forces acting upon the lumbosacral t during a lifting task. Note, the forces differ between males and females because of gender dependent differences in body

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segment proportions. That is, the majority of females have shorter legs and longer torsos than males.

ORIGINS OF HUMAN FACTORS GENESIS Many people would argue that the development of Human Factors is necessarily as old as the development of aviation. This is because Human Factors are part and parcel of any development on aviation and, therefore, their development would be considered parallel. This is however, a fairly simplistic view and it would be fair to say that Human Factors as a discipline is a reasonably modern initiative. That is not to say that elements of Human Factors such as those coming under the headings of Anthropometrics or Biomechanics have not been taken into well before the term “Human Factors” was associated with them. WORLD WAR II World War II probably provided the genesis of subject areas that now considered being part of Human Factors. What was meant is that specific research was conducted on aeroplane operations and maintenance with the prime intension reducing accident and incident rates. In 1939, Sir Frederic Bartlett in his Cambridge University laboratories was the first to build aircraft cockpit mock-ups and simulators for the prime purpose of conducting experiments that would reduce pilot error during training as well as war operations. Early researchers made significant safety advances through Human Factor applications, though these were primarily in the fields of anthropometrics, biomechanics and biophysiology.

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POST WAR DEVELOPMENTS Shortly after the war, in 1949, the Ergonomics Research Society was founded in England. This Society was the foundation of what later became the Ergonomic Society and the prime repository of Human Factors research from all over Europe. Meanwhile, a similar body was undertaking work in United States. This body first took on the name “Human Factors Society” in 1957 and the centre of research for Human Factors throughout North America. In many respects, these two organizations developed in parallel and even replicated each other’s work. It was not until recently that they ed into a single entity that is now known as “The Human Factors and Ergonomics Society”. Human Factors really started to get the attention of decision makers in aviation following the major disaster at Tenerife in 1977 when a KLM 747 ran into a Pan American 747 during takeoff at Los Rodeos airport. This accident was the catalyst for KLM to engage a number of academics under the direction of Captain Frank Hawkins to put together the first course (“KHUFAC” standing for KLM Human Factors) aimed at educating flight crew on reducing and managing errors through knowledge of Human Factor concepts. Also in the late 70’s, there were a number of accidents and incidents to US carriers that resulted in insurance companies asking for the airlines to rethink their educational strategies of flight crew. Cockpit Resource Management (CRM) courses were the result of these deliberations and they were actively taken up by most airlines in the world who could see a tangible benefit in educating their flight crew in Human Factor concepts. MODERN FOCUS Following two significant mishaps in England, Cockpit Resource Management had transformed into Crew Resource Management. The two specific incidents involved scenarios in which the cabin crew had information that could well have prevented the disaster but it was not ed on to the captain in time to do so. Cabin crew then became an integral part of the safety equation on modern airliners and they too were required to attend Human Factors courses with the express intention of reducing and managing human error. It did not long for senior management personnel in airlines to realize that these Human Factors elements played a significant role in the success or failure of the entire organization. The term “Corporate Resource Management” or “Company Resource Management” was coined by some to reflect the fact that these Human Factors skills should be thought to everyone in the organization. This is in effect what have become Human Factors and Error Management today. Many Regulatory authorities have also gone so far to require such courses to be taken for licensing purposes. In the maintenance engineering discipline, Human Factors and Error Management have evolved into Maintenance Error Management (MRM). MRM can be defined as: “Maintenance Resource Management is a general process for improving communication, effectiveness, and safety in airline maintenance operations. MRM improves safety by increasing the coordination and exchange of information between team , and

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between teams of airline maintenance crews. MRM programs link and integrate traditional human factor topics, such as equipment design, human physiology, workload, and workplace safety. Likewise the goal of any MRM program is to improve work performance and safety. They do this by reducing maintenance errors through improved coordination and communication.” HUMAN-MACHINE COMPARISON Early in the development of Human Factors as a discipline, Paul Fitts proposed the following comparison of human and machine abilities. Although rapid advances in technology promise to significantly increase "machine" abilities, this summary remains valid and a "classic" in the Human Factors field. Humans sur Machines in ability to: 1. detect small amount of visual and acoustic energy 2. perceive patterns of light or sound 3. improvise and use flexible procedures 4. store very large amounts of information for long periods and to recall relevant facts at the appropriate time 5. reason inductively 6. exercise judgment

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Machines sur Humans in ability to: 1. respond quickly to control signals, and to apply great force smoothly and precisely 2. perform repetitive, routine tasks 3. store information briefly and then to erase it completely 4. reason deductively, including computational ability 5. Ability to handle highly complex operations--to do many different things at once.

Humans are better than Machines in:  Sensory Functions  Perceptual Abilities - Stimulus Generalization - Abstract Concepts  Flexibility - Ability to Improvise  Judgment  Selective Recall  Inductive Reasoning Machines are better than Humans in:  Alertness  Speed and Power  Sensor Detection Outside Human Range  Routine Work  Computation  Short-term Memory Storage  Simultaneous Activities

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HUMAN-MACHINE DIFFERENCES Other major differences between humans and machines are:  Machines can be modified, redesigned, and retrofit -- humans cannot. Humans are born with innate, genetically determined differences that are shaped by the environment. Innate aptitudes or abilities are developed through education and training.  Machines can be manufactured to be identical--with identical, or nearly identical, output or performance. Humans are not identical and vary across all sensory, cognitive, physical and performance characteristics. Specific aspects of human performance can be made more equal through education and training. THE IMPORTANCE OF AN EFFECTIVE HUMAN FACTORS PROGRAMME IN A MAINTENANCE ORGANIZATION Humans have performance limitations: Therefore they make errors Effective Human Factors programs train employees and put systems in place to pick up those errors: Therefore those errors do not result in delays, incidents or accidents Fewer errors by engineers’ means reduced delays, incidents and accidents: Therefore the company is safer and more cost efficient A safer, more cost efficient, company means: Fewer delays  Fewer injuries to employees  Better company performance  And therefore better work place for its workers THE COST EFFECTIVENESS OF IMPLEMENTING HF PROGRAMS IN ORGANIZATIONS There are two primary reasons for including HF programs in organizations. They are:  Safety, and  Cost

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Safety has two aspects to it.  First and foremost is public safety Organizations that are better trained and present fewer errors in their routine and emergency work present a safer option to the traveling public. engers prefer to travel with a safer airline.  And second is on-the-job safety for maintenance workers Reduced error rates are reflected in the injury rates amongst staff and less down time for workers. It is worth noting here that those injuries aren’t always physical. Cost savings are a bit more tangible than safety as a reason to implement HF programs and therefore easier to identify with. It is very difficult to prove to an ant that an accident is saved from occurring but it is easier to show book figures that show definitive cost savings. Ironically, the biggest cost savings are in reduced accident rates. It is just that in ultra-safe systems such as aviation, the accident rates are so small that they become statistically insignificant.  There are cost savings through fewer operational delays and quicker turnaround times for equipments  And there are reduced costs through less downtime on equipment and workers caused by errors In summary, implementing HF programs in organizations reduces the overall cost of maintenance. Organizations are known to have run many HF programs within the different branches of the organization. HUMAN FACTOR MODELS Perhaps the most common way of expressing complex systems is to use simple models to illustrate the ideas. In aviation, Elwyn Edwards (1972) proposed the SHEL model, a name derived from the initial letters of its components to identify the components and interactions within the complex aviation industry. SHEL MODEL Software (e.g. maintenance procedures, maintenance manuals, checklist layout, etc.); Hardware (e.g. tools, test equipment, the physical structure of aircraft, design of flight decks, positioning and operating sense of controls and instruments, etc.); Environment (e.g. physical environment such as conditions in the hangar, conditions on the line, etc. and work environment such as work patterns, management structures, public perception of the industry, etc.); Liveware (i.e. the person or people at the centre of the model, including maintenance engineers, supervisors, planners, managers, etc.)

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In of human factors, the interactions between these components were the areas that created most errors in aviation. Therefore, an understanding of each of the elements and how they interacted would provide a means of reducing error. Most particularly, it was the human error that required closest inspection so the interactions between the Liveware and the other elements became the prime focus area for human factors. LIVEWARE - SOFTWARE The interactions between individuals and the organizations policies, procedures, manuals, etc., mostly contain errors of interpretation or understanding. Many of the manuals, engineers were expected to use were not friendly, policies were interpreted differently by different supervisors and rules were often ignored because they conflicted with common sense. LIVEWARE – HARDWARE The interactions between individuals and the machinery or tools that they used also required some major rethinking to reduce the error rate. Controls that required extreme physical strength, displays that were easy to misread and hours of boring monitoring contributed to high error rates in these interactions. friendly controls and displays and better understanding of the relative strengths of humans and machines provided a platform for reducing error rates considerably. Alarm systems were also provided to keep operations within the established parameters. LIVEWARE – ENVIRONMENT Engineers were often asked to work in hostile physical conditions without satisfactory protective equipment and asked to take responsibility for safety aspects that were compromised by lack of funding for the right equipment. In many cases, errors were significantly reduced just by providing the right safety were. For example ramp staff, which were often distracted by high noise levels, could concentrate on their responsibilities much more effectively while wearing the right grading of ear protection. Occupational health and safety legislation has been enacted in many countries now to reduce error rates at the interaction between Liveware and the Environment.

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HE SHELL MODEL In 1984, Frank Hawkins proposed that the interactions between people were also a significant arena for error generation. He proposed the addition of another Liveware to the model to take of the interactions between people at both the macro and micro level. This became the SHELL Model.

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LIVEWARE – LIVEWARE This interaction concentrated on errors caused by miscommunication between individuals, poor teamwork in small group situations and ineffective leadership by supervisors and managers that generated errors on the workshop floor. Training and recognition of individual capabilities within the work environment were coupled with redundancy systems to pick up on errors caused by misunderstandings became a significant part of the human factors research efforts to improve safety, effectiveness and efficiency. As will be covered in this document, man - the “Liveware” - can perform a wide range of activities. Despite the fact that modern aircraft are now designed to embody the latest self-test and diagnostic routines that modern computing power can provide, one aspect of aviation maintenance has not changed: maintenance tasks are still being done by human beings. However, man has limitations. Since Liveware is at the centre of the model, all other aspects (Software, Hardware and Environment) must be designed or adapted to assist his performance and respect his limitations. If these two aspects are ignored, the human - in this case the maintenance engineer - will not perform to the best of his abilities, may make errors, and may jeopardize safety. Thanks to modern design and manufacturing, aircraft are becoming more and more reliable. However, it is not possible to re-design the human being: we have to accept the fact that the human being is intrinsically unreliable. However, we can work around that unreliability by providing good training, procedures, tools, duplicate inspections, etc. We can also reduce the potential for error by improving aircraft design such that, for example, it is physically impossible to reconnect something the wrong way round.

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THE SCHELL MODEL In 1994, Professor Graham hunt from Massey University in New Zealand proposed that all of these interactions necessarily take place within a cultural context. While many commentators see these aspects as part of the environment, professor hunt believes that the organisational, national and ethnic backgrounds of individuals play a profound part in the interactions of the shell model and are currently not addressed satisfactorily in most cases. He has proposed the SCHELL (pronounced skell) model. This is still a debateable point.

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THE IMPORTANCE OF TRAINING IN REDUCING MAINTENANCE ERRORS Public and personal safety relies on competent individuals and systems working together to meet specific safety standards. It is difficult to overestimate the importance to training in this process. In many response individuals are a product of the training they receive and apart from a few innate abilities and a large number of experiences, what the individuals learn through training reflects their capability and their competence. For example, it would not be cost effective of an organization to purchase expensive, highly specialized equipments ( a common requirement in aviation) , if they did not get their personal trained appropriately on that machinery. Further, these personal can risk serious injury to themselves or to airline engers if they are not competent in operating the machinery. In the same way, all training is primarily aimed at reducing errors of one from or another. This human factor courses is just another example of the company providing training to individual with the intention of reducing maintenance errors that may have occurred if he or she had not undertaken this training. Time will tell whether it has been successful. 9.1.2 STATISTICS INCIDENTS AND ACCIDENTS ATTRIBUTABLE TO HUMAN FACTORS / HUMAN ERROR In 1940, it was calculated that approximately 70% of all aircraft accidents were attributable to man’s performance, that is to say human error. When the International Air Transport Association (IATA) reviewed the situation 35 years later, they found that there had been no reduction in the human error component of accident statistics.

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A study was carried out in 1986, in the USA by Sears, looking at significant accident causes in 93 aircraft accidents. These were as follows:

Causes/ major contributory factors

% of accidents in which this was a factor

Pilot deviated from basic operational procedures

33

Inadequate cross-check by second crew member

26

Design faults

13

Maintenance and inspection deficiencies

12

Absence of approach guidance

10

Captain ignored crew inputs

10

Air traffic control failures or errors

9

Improper crew response during abnormal conditions

9

Insufficient or incorrect weather information

8

Runways hazards

7

Air traffic control/crew communication deficiencies

6

Improper decision to land

6

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As can be seen from the list, maintenance and inspection deficiencies are one of the major contributory factors to accidents. The UK CAA carried out a similar exercise1 in 1998 looking at causes of 621 global fatal accidents between 1980 and 1996. Again, the area “maintenance or repair oversight / error / inadequate” featured as one of the top 10 primary causal factors. It is clear from such studies that human factors problems in aircraft maintenance engineering are a significant issue, warranting serious consideration.

9.1.3 INCIDENTS During the late 1970’s, there were a great number of heavy airline accidents that made headlines around the world. These include the KLM and PAN AM jumbo jets at Tenerife in 1977, the air New Zealand DC 10 at Mount Erebus in Antarctica in 1979, and the British airways Trident midair collision with the lnexAdria DC 9 over Zagreb in 1976. One of those headline makers was United Airlines Flight 173 which crashed just short of the runway at Portland, Oregon in the United States on December the 28th, 1978. PORTLAND OREGON A synopsis of the accident shows that the DC 8 did not have the three green lights indicating that all the landing gear was down, locked and ready for landing when they were on final approach. The light crew requested an overshoot and some time to circle of the unpopulated marsh area some 10 miles from the airport, while they sorted out the problem. The crew became totally immersed in solving the problem and neglected to notice their fuel status. It becomes apparent that they ran out of fuel and were unable to make it to the airfield. This had all of the hallmarks of the everglades accident in 1972 where 99 lives were lost for a 60 cent light bulb. KEGWORTH The British midland 737-400 accident at Kegworth also became a key event in the development of human factors in aviation. In this case, an almost brand new Boeing 737400, on climb out from London’s Heathrow airport, on its way to Belfast, suffered what appeared to be engine damage on number 1 (the left hand) engine. The flight crew shut down the number 2 (right hand ) and the aircraft eventually crashed on the M1 motorway. The investigation revealed that things were not quite as simple as first through. As the aircraft was climbing through 28,300 feet the outer of one blade in the fan of the number 1 (left) engine detached. This gave rise to a series of compressor stalls in the number 1 engine, which resulted in airframe shuddering. Ingress of smoke and fumes to the flight deck and fluctuations of the number 1 engine parameters. Believing that the number 2 engine had suffered damage, the crew throttled that engine back and 1 engine ceased as soon as the number 2 engine was throttled back. This persuaded the crew that they had dealt correctly with the emergency. They then shut down

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the number2 engine. The number1 engine operated apparently normally after the initial period of severe vibration and during the subsequent descent. The crew initiated a diversion to east midland airport and received radar direction from air traffic control to position the aircraft for an instrument approach to land on runway 27.

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The approach continued normally, although with a high level of vibration from the no.1 engine, until an abrupt reduction of power, followed by a fire warning, occurred on this engine at a point 2.4 nm from the runway. Efforts to restart the no.2 engine were not successful. The aircraft initially struck a field adjacent to the eastern embankment of the M1 motorway and then suffered a second severe impact on the sloping western embankment of the motorway. Of the eight crew and 118 engers on board that day, 39 engers died in the accident and further 8 engers died later from their injuries. Of the other 79 occupants, 74 suffered serious injury. The cause of the accident was that the operating crew shut down the number 2 engine after a fan blade had fractured in the number 1 engine. This engine subsequently suffered a major thrust loss due to secondary fan after power had been increased during the final approach to land. The air accident investigation Bureau of the United Kingdom cited the following as the contributing factors:  The combination of heavy engine vibration, noise, shuddering and an associated smell of fire were outside their training and experience.  They reacted to the initial engine problem prematurely and in a way that was contrary to their training.  They did not assimilate the indications on the engine instrument display before they throttled back the no.2 engine.  As the engine was throttled back, the noise and shuddering associated with the surging of the no 1 engine ceased, persuading them that they had correctly identified the defective engine.  They were not informed of the flames which had emanated from the no 1 engine and which had been observed by many on board, including 3 cabin attendants in the cabin. Several points come to mind when reading through that list; the first is way would two very experienced (12000 h and 9000h) pilots make such a simple error. It can be certain that they did not do it on purpose. Second is that there would not have been any accident if the engine had not failed in the first place, but that seems to have been conveniently forgotten when there is someone to blame, i.e. The pilots. And third, the captain made an announcement across the PA that he was shutting down the right hand engine when, to the engers and cabin crew, it was very clear that the left hand engine was the one having the problem. This accident followed another disaster when a British Airways 737 caught fire on the ground at Manchester. Forty three people died that day and though the engers and cabin crew could see the seriousness of their situation, none of this urgency was

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transmitted to the pilots in the cockpit who were oblivious to the mayhem going on behind them because they could not see it. COCKPIT RESOURCE MANAGEMENT (CRM) Investigators, united airline staff and other professional pilot were understandably shocked that some of their men could make such a basic error. Furthermore, united airlines were getting some fairly negative press at this stage and to their credit, decided to do something about it. The airlines analyze the problem areas that had been contributing factors to the accident and created what became know as a “cockpit resource management workshop” which they required all of their flight crew to attend. This was an innovative requirement but immediately yielded positive results to the extent that a range of other airlines started their own programmers very soon afterwards. As time went on, it is fair to say that insurance companies began to require airlines to undertake CRM training before their insurance would be validated. To united airline’ credit, they shared their expenses and results with the aviation safety community which enabled a much quicker dissemination of safety initiatives than would be the case if those courseware kept or held in confidence. The first CRM workshops concentrated on communication issues as these were seen to be the primary casual factors in some of the better known aircraft accidents. Assertiveness training for first officers was generally included as an element of the course within the context of the authority gradient across the cockpit. Some CRM facilitators could see the benefits of including further subject matter in these workshops and over time, many of the subjects that are classified today as human factors were included in the workshop. Subjects such as street management, fatigue management, leadership and teamwork were common in CRM courses through there was no specific formula and airlines included the material that they, or their advisors, felt most appropriate. These accidents led directly to the inclusion of cabin crew in CRM courses and a change in the emphasis from cockpit to crew. This is still the case with most airlines today and indeed, in some organizations it has been extended to corporate resource management or company resource management to take of all of those contributing personal outside the flight crew. But where do the maintenance engineers fit in?

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THE CONVERTIBLE 737 The engineers came to importance in human factor with a rather unusual incident involving aloha airlines flight 243 on April 28th, 1988. In this accident, flight 243 experienced an explosive decompression and structural failure at FL240. Approximately, 18 ft of cabin skin and structure aft of the cabin entrance door and above the enger floor line, separated from the aircraft. One flight attendant who was standing in the aisle was swept overboard. The flight diverted to Manui and a landing was accomplished. The subsequent investigation found the following points:  Examination of the aircraft revealed disbanding and fatigue damage which led to the failure of the lap t at s 101 and the separation of the fuselage upper skin between stations 360 and 540.  The national transportation safety board determines the probable cause(s) of this accident / incident as follows: - FUSELAGE, ATTACHMENT..FATIGUE - FUSELAGE, ATTACHMENT.. SEPARATION The hardest part to accident was the fact that the aircraft had been examined by two inspectors, one with 22years experience and the other, the chief inspector with 33 years experience, and neither of them had found any of over 240 cracks in the skin of the aircraft.

The report cited the following specific contributing factors:  Maintenance, inspection – improper.  Company maintenance personal supervision – inadequate.  Company/ operator management - inadequate surveillance of operation.  These finding brought about a overabundance of human factors issues as people tried to answer the question: “how did these experienced engineers make these errors?”

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CCC HPIM MRM Continental airlines first came up with the term “crew coordination concept” (CCC) to include engineers in their crew resource management workshops. An air Ontario accident at Dryden in Ontario led to a specific course called “human performance in maintenance” (HPIM) and the current evolution of these programmers has become “maintenance resource management (MRM) which is organization specific rather than generic. It has the added advantage of just targeting those issues that relate to maintenance engineers rather than flight crew and cabin crew as well. THE HUMAN FACTORS ELEMENTS THAT CAN EVIDENT WHEN CARRYING OUT SPECIFIC AIRCRAFT MAINTENANCE TASKS SUCH AS INSPEECTION OF AGING AIRCRAFT AND OTHER REPETITIVE AND BORING ACTIVES. The HPIM Initiative following the Ontario accident led to maintenance engineering focus group identifying what has been termed: “the dirty dozen” of maintenance engineering. These are all human factors. They are:  Lack of communication  Complacency  Lack of knowledge  Distraction  Lack of teamwork  Fatigue  Lack of resources  Pressure  Lack of assertiveness  Stress  Lack of awareness  Norms

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With respect to lack of communication, this has been a well – established cause of error in the aviation industry and had been included on CRM courses since they first began, so it is no surprise to see this as one of the dirty dozen. Lack of communication in this context means not ing on information, written or oral, and more particular, ing on information but not being sure that it has been understood properly. Complacency is a real danger for engineers. Following the Aloha incident, the FAA issues an airworthiness directive (AD) requiring the close visual inspection of 1300 rivets on every single Boeing 737. If ever there was an opportunity for complacency in the inspection business, it was provided by the FAA in this case. In of lack of knowledge, it is impossible to know all there is to know in the maintenance engineering business. In the absence of specific knowledge, it is a human trait to fill in the gaps with “ good enough” actions or nothing, hiding behind the expression” I didn’t know what to do”. Distractions in the engineering business are common. Irrespective of whether the distraction is home life or just a friend at work interrupting when work is done, distractions have been cited on many occasions as the reason for checks or steps being missed during an engineering process. Teamwork, or rather the lack of it will be cited a number of times in this course as a major source of error. Humans are all of a number of teams and it is important that they play their role in each team to the best of their ability. Fatigue has been recognized as a source of error for a long time now but aviation personal works in a 24 hour industry and the demands are high. Education would seem to be the major countermeasure to this problem at the moment but more on that later. Lack of resources is unlikely to be a problem in most organization but there will be times when the person might say ‘I wish I had just one more person to help us with this job’ or ‘where are the spare floodlights when you need them’. It is easy to improvise but it is also easy to get caught out improvising. Pressure comes in many and varied forms. Time pressure, for example, will always be part of the aviation industry and particularly for engineers. An aircraft cannot make any money when it is on the ground and the sooner it can be turned around the better. Peer pressure could make a person work late hours at the expense of the person’s family life and the expectations of managers can lead to pressures to work harder or further their education outside the normal working day. These can all reduce attention to detail when it is most needed – prime breeding ground for errors.

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Lack of assertiveness is generally a result of the hierarchy or rank structure in an organization. There are both formal and informal versions. The formal ones are normally part of the company or profession structure whiles the informal ones are related to where a person perceives oneself amongst peers and the organization. There is an inclination for individuals to react according to their status rather than to their competence or ability. This is a big issue when it comes to inspection and checking, which are two of the prime roles of maintenance engineers. Stress is part and parcel of every day lives. Despite urban mythology to the contrary, stress cannot be left behind from one’s personal lives. When a person goes to work, and simple things such as an argument with the person’s spouse or partner at home in the morning can result in errors at work. Situation awareness is also a big problem in the aviation industry and there is a whole module at the end of this course devoted specifically to situation awareness. Norms are apart of the culture of an origination and each organization has sets of norms which are positives and those which are negative. The trick is to enhance the positive and suppress the negative. There have been several ‘high profile’ incidents and accidents which have involved maintenance human factors problems. The Human Factors in Aviation Maintenance and Inspection (HFAMI) web site (http://hfskyway.faa.gov) lists 24 NTSB accident reports where maintenance human factors problems have been the cause or a major contributory factor. In the UK, there have been several major incidents and accidents, details of which can be found on the AAIB web site (www.aaib.dtlr.gov.uk). Some of the major incidents and accidents are summarized below. These are:  Accident to Boeing 737, (Aloha flight 243), Maui, Hawaii, April 28 1988  Accident to BAC One-Eleven, G-BJRT (British Airways flight 5390), over Didcot, Oxfordshire on 10 June 1990  Incident involving Airbus A320, G-KMAM at London Gatwick Airport, on 26 August 1993  Incident involving Boeing 737, G-OBMM near Daventry, on 23 February 1995

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The accident involving Aloha flight 243 in April 1988 involved 18 feet of the upper cabin structure suddenly being ripped away in flight due to structural failure. The Boeing 737 involved in this accident had been examined, as required by US regulations, by two of the engineering inspectors. One inspector had 22 years experience and the other, the chief inspector, had 33 years experience. Neither found any cracks in their inspection. Post accident analysis determined there were over 240 cracks in the skin of this aircraft at the time of the inspection. The ensuing investigation identified many humanfactors-related problems leading to the failed inspections. As a result of the Aloha accident, the US instigated a programme of research looking into the problems associated with human factors and aircraft maintenance, with particular emphasis upon inspection. On June 10th 1990 in the UK, a BAC1-11 (British Airways flight 5390) was climbing through 17,300 feet on departure from Birmingham International Airport when the left windscreen, which had been replaced prior to flight, was blown out under the effects of cabin pressure when it overcame the retention of the securing bolts, 84 of which, out of a total of 90, were smaller than the specified diameter. The commander was sucked halfway out of the windscreen aperture and was restrained by cabin crew whilst the co-pilot flew the aircraft to a safe landing at Southampton Airport. The Shift Maintenance Manager (SMM), short-handed on a night shift, had decided to carry out the windscreen replacement himself. He consulted the Maintenance Manual (MM) and concluded that it was a straightforward job. He decided to replace the old bolts and, taking one of the bolts with him (a 7D), he looked for replacements. The storeman advised him that the job required 8Ds, but since there were not enough 8Ds, the SMM decided that 7Ds would do (since these had been in place previously). However, he used sight and touch to match the bolts and, erroneously, selected 8Cs instead, which were longer but thinner. He failed to notice that the countersink was lower than it should be, once the bolts were in position. He completed the job himself and signed it off, the procedures not requiring a pressure check or duplicated check. There were several human factors issues contributing to this incident, including perceptual errors made by the SMM when identifying the replacement bolts, poor lighting in the stores area, failure to wear spectacles, circadian effects, working practices, and possible organizational and design factors.

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An incident in the UK in August 1993 involved an Airbus 320 which, during its first flight after a flap change, exhibited an un-demanded roll to the right after takeoff. The aircraft returned to Gatwick and landed safely. The investigation discovered that during maintenance, in order to replace the right outboard flap, the spoilers had been placed in maintenance mode and moved using an incomplete procedure; specifically the collars and flags were not fitted. The purpose of the collars and the way in which the spoilers functioned was not fully understood by the engineers. This misunderstanding was due, in part, to familiarity of the engineers with other aircraft (mainly 757) and contributed to a lack of adequate briefing on the status of the spoilers during the shift handover. The locked spoiler was not detected during standard pilot functional checks. In the UK in February 1995, a Boeing 737-400 suffered a loss of oil pressure on both engines. The aircraft diverted and landed safely at Luton Airport. The investigation discovered that the aircraft had been subject to borescope inspections on both engines during the preceding night and the high pressure (HP) rotor drive covers had not been refitted, resulting in the loss of almost all the oil from both engines during flight. The line engineer was originally going to carry out the task, but for various reasons he swapped jobs with the base maintenance controller. The base maintenance controller did not have the appropriate paperwork with him. The base maintenance controller and a fitter carried out the task, despite many interruptions, but failed to refit the rotor drive covers. No ground idle engine runs (which would have revealed the oil leak) were carried out. The job was signed off as complete. In all three of these UK incidents, the engineers involved were considered by their companies to be well qualified, competent and reliable employees. All of the incidents were characterized by the following:  There were staff shortages  Time pressures existed  All the errors occurred at night  Shift or task handovers were involved  They all involved supervisors doing long hands-on tasks  There was an element of a “can-do” attitude  Interruptions occurred  There was some failure to use approved data or company procedures  Manuals were confusing  There was inadequate pre-planning, equipment or spares

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INCIDENTS AND ACCIDENTS - A BREAKDOWN IN HUMAN FACTORS In all of the examples above, the accident or incident was preventable and could have been avoided if any one of a number of things had been done differently. In some cases, a number of individuals were involved and the outcome could have been modified if any one of them had reacted or queried a particular action. In each situation however, the individuals failed to recognize or react to signs of potential hazards, did not react as expected of them, or allowed themselves to be diverted from giving their attention to the task in hand, leaving themselves open to the likelihood of committing an error. As with many incidents and accidents, all the examples above involved a series of human factors problems which formed an error chain. If any one of the links in this ‘chain’ had been broken by building in measures which may have prevented a problem at one or more of these stages, these incidents may have been prevented.

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MURPHY’S LAW EASA part 66 Module 9 syllabus also requires the inclusion of Murphy’s Law as a topic. There are several versions of the law. However, the most know version is the first one in the list.  If anything can go wrong, it will.  If there is a possibility of several things going wrong, the one that will cause the most damage will be the one to go wrong. Corollary: if there is a worse time for something to go wrong, it will happen then.  If anything just cannot go wrong, it will anyway.  If an individual perceives that there are four possible ways in which something can go wrong, and circumvent these, then a fifth way , unprepared for , will promptly develop.  Left to themselves, things tend to go from bad to worse.  If everything seems to be going well, something obviously had been overlooked.  Nature always sides with the hidden flaw.

There is a tendency among human beings towards complacency. The belief that an accident will never happen to “me” or to “my Company” can be a major problem when attempting to convince individuals or organizations of the need to look at human factors issues, recognize risks and to implement improvements, rather than merely to pay ‘lipservice’ to human factors. If everyone could be persuaded to acknowledge Murphy’s Law, this might help overcome the “it will never happen to me” belief that many people hold. It is not true that accidents only happen to people who are irresponsible or ‘sloppy’. The incidents and accidents described earlier show that errors can be made by experienced, well-respected individuals and accidents can occur in organizations previously thought to be “safe”.

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MODULE 9

HUMAN FACTORS

SUB MODULE 9.2

SAFETY CULTURE / ORGANIZATIONAL FACTORS

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CONTENTS Safety Culture / Organizational Factors ............................................2-1 What Is Safety Culture? .....................................................................2-1 Can A Safer Culture Be Engineered? ..................................................2-2 Creating A Just Culture ......................................................................2-2 The Foresight Test..............................................................................2-4 The Substitution Test .........................................................................2-5 Getting The Balance Right .................................................................2-5 Creating A Reporting Culture .............................................................2-5 Creating A Learning Culture ...............................................................2-7 Types Of Safety Culture: ..................................................................2-10

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9.2. SAFETY CULTURE / ORGANIZATIONAL FACTORS WHAT IS SAFETY CULTURE? Safety culture is a term that nearly everyone uses, but few can agree upon its precise meaning, or how it can be measured. The social science literature offers an abundance of definitions, which is not particularly helpful, but taken together they suggest that the elements of a safety culture can be sub-divided into two parts. The first comprises the beliefs, attitudes and values – often unspoken – of an organization’s hip regarding the pursuit of the safety. The second is more concrete and embraces the structures, practices, controls, and policies that an organization possesses and employs to achieve greater safety. Some of the more important attributes of a safety culture are listed below. A safe culture is the ‘engine’ that continues to drive the organization towards the goal of maximum attainable safety regardless of current commercial pressures or who is occupying the top management posts. The commitment of the CEO and his immediate colleagues exerts a powerful influence upon an organization’s safety values and practices but top managers come and go, and a truly safe culture must endure despite these changes. A safe culture reminds the organization’s to respect the operationalhazards, and to expect that people and equipment will fail. It accepts these breakdowns as the norm and develops defences and contingency plans to cope with them. A safe culture is a wary culture, one that has a ‘collective mindfulness’ of the things that can go wrong. A safe culture is an informed culture, one that knows where the ‘edge’ is without having to fall over it. This is no easy task in industries with relatively few bad events. An informed culture can only be achieved by creating an atmosphere of thrust in which people are willing to confess their errors and near misses. Only in this way can the system identify its error-provoking situations. Only by collecting, analyzing and disseminating information about past events and close calls can it locate where the boundaries between safe and unsafe operations might lie. Without such a corporate ‘memory’ the system cannot learn. An informed culture is just culture that has agreed and understood the distinction between blame-free and culpable acts. Some unsafe acts will warrant disciplinary action. They are likely to be very few, but they cannot be ignored. Without as just culture, it is difficult if not impossible, to establish an effective reporting culture.

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A safe culture is a learning culture in which both reactive and proactive measures are used to guide continuous and wide-reaching system improvements rather than mere local fixes. A learning culture is one that uses the discrepancies that inevitably arise between what it intends and what actually happens to challenge its basic assumptions – and has the will to change them when they are shown to be maladaptive. This list of attributes makes it clear that a safe culture has many interlocking parts. The main components are listed below. Just culture Reporting culture Learning culture

CAN A SAFER CULTURE BE ENGINEERED? The answer is yes, up to a point, but it all depends on which features of culture set out to be changed. It was stated earlier that scientific definitions present culture as having two aspects: what an organization is (beliefs, attitudes, and values), and what an organization does (structures, practices, policies and controls). Faced with a choice, most organizations would seek to change the former through various motivational measures: fear appeals, sticks and carrots (mostly sanctions), making an example of those who commit unsafe acts, naming, blaming, shaming, retraining – and, of course, that old managerial knee jerk reaction, writing another procedure. This is in keeping with the widespread person model of human error: the idea that errors and violations arise solely out of the perversity and unreliability of human nature. Although this is the wide spread view, HF specialists favour latter course – changing practices. And given below are some of the reasons why. Greet Hofstede, an expert on culture, expressed the case well when he wrote that: ‘Changing collective values of adult people in an intended direction is extremely difficult, if not impossible. Values, beliefs and attitudes can be changed, but not necessarily by a direct assault. It is often better to approach the issue obliquely by setting out to change an organization’s practices. Although there is a wide spread view that mental states like attitude and beliefs drive behaviour, it can also work the other way round. Introducing practices and structures that are seen to work effectively have a way of bringing people’s values into line with them. CREATING A JUST CULTURE Creating a just culture – it could just as well be called a trust culture – is the critical first step in socially engineering a safe culture. No one is going to confess his or her errors and near misses in a wholly punitive culture. Trust is the essential prerequisite for a reporting culture – and hence an informed culture. Nor is a wholly blame-free culture feasible since some unsafe acts, albeit a very small proportion, are indeed culpable and deserve severe sanctions. It would be silly to pretend otherwise since the reckless actions of

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a small minority not only endanger the safety of the system as a whole, but also pose an immediate threat to other maintenance staff. If these few are seen go unpunished, then management loses credibility. But the y would also lose it if they failed to discriminate between this minority of egregious acts and the largely blameless errors that comprise more than 90% of the total number committed. A just culture hinges critically on a collectively agreed and clearly understood distinction being drawn between acceptable and unacceptable behaviour. But how should this distinction is made? A natural instinct is to draw the line between errors and violations. Errors are largely unintended, whereas most violations have an intentional component. Criminal law makes the distinction between a ‘guilty act’ (actusreus) and a ‘guilty mind’ (mensrea). Except in situations of absolute liability (for example, shooting a red light), neither by itself is sufficient to secure a conviction: to achieve a guilty verdict both the act and the intention to commit the act must usually be proved beyond reasonable doubt. At first sight, therefore, the decision appears to be fairly straightforward, simply determine whether the unsafe act involved non-compliance with safe operating procedures. If it did, then it would be culpable. Unfortunately, the matter is not quite so simple as following three scenarios will illustrate. In all three cases, an aircraft maintenance engineer is asked to inspect the fuselage of an aircraft for any cracked rivets that could jeopardize its airworthiness. The company procedures require that engineers perform this inspection using an appropriate work stand and an array of lights. Scenario A: The engineer collects the work stand and lights from the stores and carries out an approved inspection. But he erroneously fails to spot a cracked rivet. Scenario B: The engineer decides not to bother with the work stand and approved lights. Instead, he conducts a cursory examination by walking underneath the aircraft with a flashlight. He too misses a cracked rivet. Scenario C: The engineer goes to the store to fetch the work stand and the lights, but finds the work stand missing and lights unserviceable. Conscious that the aircraft will soon be in service, he takes a flash light and carries out his inspection from beneath the aircraft. He too misses the cracked rivet. Note that the outcome is same in all three cases: a cracked rivet is not detected. It is clear, however, that the undergoing behavior is quite different in the above three cases. In Scenario A , the engineer was compliant with the procedures. In Scenario B, the engineer could not be bothered to comply. In Scenario C, the engineer intended to comply, but equipment deficiencies made it impossible. Violations were committed in both B and C, but the underlying motivation was clearly not the same. In B, the engineer deliberately took a short cut that increased the probability of missing a cracked rivet. In C, the engineer sought to do the best he could with the inadequate resources at hand. The moral of these three scenarios is clear. Neither the error nor the mere act of violating is sufficient to warrant being labelled as unacceptable. To establish culpability, it is

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necessary to review the sequence of behaviour of which the error or violation was part. The key issue is did the individual deliberately and without good cause engage in a course of actions likely to promote error? The above scenario shows that the simple distinction between errors and violations can be misleading. Non-compliance may provide a clue to unacceptable behaviour, but it is not sufficient to establish it. Many violations, as Scenario C demonstrated, are systeminduced, the product of inadequate tools and equipment, rather than a desire for an easier way of working on the part of the individual. It is also the case that manuals and procedures can be incomprehensible, unworkable, unavailable or just plain wrong. Where these deficiencies are apparent, sanctioning the non-compliant individual will not enhance system safety. At best, it will skimpy be seen as an indication of management's short-sightedness and induce a sense of 'learned helplessness' in the workforce; at worst, it will be viewed as a symptom of management malevolence. In neither case is an atmosphere of trust and respect likely to flourish. Can the law help? For negligence, largely an issue for civil law, the enquiry begins with some human action that has brought about a bad consequence. The question that then arises is 'Was this an outcome that a "reasonable and prudent person" could have foreseen and avoided?' Recklessness, a matter for criminal law, involves taking a deliberate and unjustifiable risk. The distinguishing feature is the intention. The actions do not need to have been intended in the case of negligence, but it is necessary to prove prior deliberation to achieve a conviction for recklessness. How can one make sensible decisions about culpability without a law degree? There are two rule-of-thumb tests that can be applied to each serious event in which unsafe acts were significant contributors. THE FORESIGHT TEST Did the individual knowingly engage in behaviour that an average maintenance staff would recognize as being likely to increase the probability of making a safety-critical error? In any of the following situations, the answer to this question might well be 'yes’ and hence indicative of culpability. Performing maintenance under the influence of a drug or substance known to impair performance. Clowning around whilst driving a towing vehicle or forklift truck or whilst handling other potentially damaging equipment. Becoming excessively fatigued as a consequence of working a double shift. Taking unwarranted short cuts like g off on jobs before they are completed. Using tools, equipment or parts known to be sub-standard or inappropriate. In any of these situations, however, there could be extenuating circumstances. In order to resolve these issues, it is necessary to apply the substitution test.

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THE SUBSTITUTION TEST This involves performing a mental test in which the individual actually concerned in the event will be substituted for someone else doing the same kind off work and possessing comparable training and experience. The question then is 'In the light of the prevailing circumstances, would this other person have behaved any differently?' If the answer is 'probably not' then apportioning blame has no role to play and would probably obscure the underlying systemic deficiencies. A further question can be put to a group of the erring person's peers: 'Given the situation in which the event occurred, could you be sure that you would not have committed the same or a similar type of unsafe act?' If the answer is again 'no' then blame is very likely to be inappropriate.

GETTING THE BALANCE RIGHT The policy being advocated here has two elements: on the one hand, there is 'zero tolerance' for reckless conduct, but this is linked, on the other hand, to creating a widespread confidence that the vast majority of unintended unsafe acts will go unpunished. Sacking or prosecuting truly reckless offenders, particularly where there is a prior history of similar offences, not only makes the working environment safer, it also sends out a clear message regarding the consequences of unacceptable behaviour. This encourages the vast majority of the workforce to perceive the organizational culture as being just in that it knows the difference between bad acts and honest errors. Natural justice works two ways. Punishments for the few can protect the innocence of the many. It will also encourage the latter to come forward with s of errors and near misses. As we shall see later, one of the defining characteristics of high reliability organizations is that they not only welcome such reports, but also commend, even reward, the reporters. CREATING A REPORTING CULTURE Even with a just culture, there are still a number of psychological and organizational barriers to be overcome before a reporting culture can be created. The first and most obvious is a natural disinclination to confess one’s blunders - we do not want to be held up to ridicule. The second is the suspicion that such reports might go on the record and count against us in the future. The third is scepticism. If we go to the trouble of writing an event report that reveals system weaknesses, how can we be sure that management will act to improve matters? Fourth, actually writing the report takes time and effort. Why should we bother?

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Below are some of the characteristics of successful reporting programs. Each feature is designed to overcome one or other of the barriers outlined above. De-identification - How this is achieved depends on the culture of the organization. Some people prefer complete anonymity - though this has the disadvantage of making it difficult to seek further information to fill in the gaps in the story. Other organizations are content with confidentiality, where the reporter is known only to a very few people. Protection. - Organizations with successful schemes generally have a very senior manager issue a statement guaranteeing that any reporter will receive at least partial indemnity against disciplinary procedures. This usually requires the report to be made within some specified time after the event. It is not possible to offer complete immunity to sanctions since - as we have discussed at length above 'some acts are indeed culpable. However, the experience of these successful programs suggests that such circumscribed guarantees are sufficient to elicit large numbers of reports of honest errors. Separation of functions. - Successful programs separate the agency or department collecting and analyzing the reports from those bodies with the authority to initiate disciplinary proceedings. . - Successful programs recognize that reports would soon dry up if the workforce felt they were sending them into an organizational black hole. Rapid, useful, accessible and intelligible to the reporting community is essential. This is often achieved by publishing summary reports of the issues raised and the counter-measures that have been implemented. Some large organizations, like NASA, also maintain databases that are available to legitimate researchers and analysts. Ease of making the report. - Some organizations started their programs with forms that asked a limited number of forced choice questions in which respondents were required to indicate which of the listed error types or environmental conditions were relevant to their events. Experience soon showed, however, that reporters prefer a more open and less constrained format. Later versions of the report form encouraged free text reporting in which respondents were able to tell a fuller story and express their own perceptions and judgments. Stories are an excellent way of capturing the complex interaction of many different factors. Such s may take longer to complete, but reporters prefer them, particularly since they provide opportunities to express their own ideas about what should be done to prevent a recurrence.

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There is no one best way to create a successful reporting system. The list above merely indicates some of the features that have overcome the barriers to filing useful event reports. Each organization must be prepared to experiment to discover what works best. Perhaps paradoxically, a successful scheme is often seen as one that attracts a steadily growing volume of event reports. While this is likely to be a valid interpretation in the early stages of a programme, logic dictates that a time will come when an increase in the number of event reports cannot simply be taken as a sign of greater trust - it could also mean that a larger number of safety-critical events are occurring within the system. To the best of our knowledge, however, very few, if any, reporting programs have yet reached this level of discrimination. In any case, the mere volume of reports is never going to be a good index of system safety. It is likely that the numbers alone will always underestimate the true incidence of errors and near misses. The greatest value of a safety information system lies in its ability to identify recurrent event patterns, error traps and gaps or weaknesses in the defences. CREATING A LEARNING CULTURE The most important prerequisite for a learning culture is a reporting culture. Without an effective incident and near miss reporting scheme that collects, analyses and disseminates safety-related information, particularly that concerning the location of safety or quality 'black spots', the organization is not only unaware of the risks, but also lacks a memory. But even when these elements are present, it is still necessary for the organization to adopt the most appropriate learning mode. The social science literature has identified two distinct types of organizational learning: single-loop and double-loop learning. The central boxes in Figure 2.1 show the sequential stages involved in organizational action. They begin with the organization’s basic assumptions about how things work and how things are done. This 'mental model' shapes the goals and the actions. Once the actions are performed, it is necessary to see whether the actual results conform to the desired results. When there is a discrepancy - results gap - some modifications need to be made to either the actions or their underlying assumptions. In single-loop learning only the actions are reviewed. This is the course that organizations subscribing to the 'person model' of human error are most likely to follow. They look for deviant performance on the part of the people who carried out the actions, and its discovery is viewed as the ‘cause’ of the discrepant results. The learning process stops once person-focused counter-measures (naming, blaming, shaming, retraining, and writing another procedure) have been applied. This is single-loop learning and, like the person model of error, it is very widespread. The results of the 'learning' are likely to be restricted to engineering ‘retro-fixes' and disciplinary action. Double-loop learning goes one very important stage further. It not only reviews the prior actions but also challenges the organizational assumptions that prompted them. Double-loop teaming leads to global reforms rather than local repairs, and to the adoption of a 'system model' of human error that is concerned not so much with who blundered, but

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how and why the organization's policies, practices, structures, tools, controls and safeguards failed to achieve the desired result.

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John Carroll of the MIT Sloan School of Management has made an extensive study of how a number of high-hazard organizations learn from experience - in particular, from the work of problem or event investigation teams. He and his colleagues produced the fourstage model of organizational learning that is summarized below. Local stage. Learning is mainly single-loop and is based primarily on the skills and experience of specific work groups. Behaviours may be adjusted after comparison with performance standards, but the underlying assumptions are not challenged. Learning is constrained by a tendency to deny any wider systemic problems and by limited expertise Control stage. Many modem industries seek to improve operations and avoid badevents through bureaucratic controls such as sanctions, incentives, standard operating procedures and formal routines. Strenuous efforts are made to limit variation and to avoid surprises. There is a strong preference for single-loop local fixes. Many organizations believe in strict compliance to the rules and have a relatively simple view of cause and effect. Such an operational style is often successful in stable environments, but it is ill suited to an uncertain, dynamic and turbulent world. Open stage. The spur to moving into this early stage of double-loop learning is often the need to accommodate widely differing views about the nature of a problem and its solutions. At first, these divergent views may be seen as disruptive, and efforts are made to bring the outliers into line. But eventually it is recognized that the world is not a simple place and that each of these differing views has some validity. Managers often find this a very uncomfortable stage, but recognition of its importance can allow the challenging of cherished assumptions and the development of new and more adaptive ways of working. Deep learning stage. This is marked by an increasing tolerance for short-term difficulties (that is, the discomfort produced by discrepant views) and greater resources are allocated to the learning process. There is awareness that problems are not someone's fault, rather they are an inevitable feature of any complex system. Managers do not see themselves as 'controlling' the workforce. They see their job as providing the resources necessary for adequate performance. Assumptions are constantly under review. There is a deep-rooted respect for the way that operational hazards can damage the system. This leads to intelligent wariness rather than helpless paralysis. Bad things are expected and planned for. In summary, a deep learning organization has both the will and the resources to strive for continuous improvement.

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TYPES OF SAFETY CULTURE: THE GOOD, THE BAD AND THE AVERAGE Ron Westrum, an American social scientist, has identified three kinds of safety culture: generative, pathological and bureaucratic (or calculative). They echo many of the learning features discussed above. A major distinguishing feature is the way that an organization handles safety-related information. Generative organizations are characterized by deep learning. They ‘encourage individuals and groups to observe, to inquire, to make their conclusions known; and where observations concern important aspects of the system, actively to bring them to the attention of higher management'. Pathological organizations muzzle, malign or marginalize whistle-blowers, shirk collective responsibility, punish or cover up failures, discourage new ideas and keep one step ahead of the regulator. Bureaucratic organizations - the large majority - lie somewhere in between. They will not necessarily shoot the messenger, but new ideas often present problems. They tend to be stuck in the control stage of learning and rely heavily on procedures to minimize performance variation. Safety management tends to be isolated rather than generalized, and treated by local fixes rather than by systemic reforms. Patrick Hudson of Leiden University has extended this three-part classification into five stages, each of which needs to be ed through before the next level can be achieved. Progress through these levels is achieved by growing trust, an increasing informedness and a willingness to engage in double-loop learning. Pathological ('who cares as long as we don't get caught') Reactive (‘safety is important; we do a lot every time we have an accident') Calculative ('we have systems in place to manage all hazards'). Proactive ('we work hard on the problems we still find'). Generative ('we know that achieving safety is difficult; we keep brainstorming newways in which the system can fail and have contingencies in place to deal with them'), The most difficult step forward is between the proactive and generative stages. Many proactive organizations are tempted to rest on their laurels, but truly generative organizations know that there are always novel scenarios of system failure. They also understand that a period of time without an event is not good news, merely no news.

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MODULE 9

HUMAN FACTORS

SUB MODULE 9.3

HUMAN ERROR

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CONTENTS 9.3 HUMAN ERROR ........................................................................... 3-1 9.3.1 Error Models and Theories ...................................................... 3-2 Design versus Operator-Induced Errors ....................................... 3-2 Variable versus Constant Errors ................................................... 3-2 Reversible versus Irreversible Errors ............................................ 3-3 Slips, Lapses and Mistakes ............................................................ 3-4 The ‘Swiss Cheese Model’ ............................................................. 3-7 9.3.2 Types of Error in Maintenance Tasks ....................................... 3-8 9.3.3 Violations ................................................................................. 3-9 Errors Due to Individual Practices and Habits ............................ 3-10 Reason’s Study of Aviation Maintenance Engineering ............... 3-11 9.3.4 Implications of Errors (i.e. Accidents) .................................... 3-12 9.3.5 Avoiding and Managing Errors............................................... 3-13 The Principles of Error Management .......................................... 3-14 3.6 Human Reliability ...................................................................... 3-19 Human Error probabilities and Performance Shaping Factors

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9.3 HUMAN ERROR It has long been acknowledged that human performance is at times imperfect. Nearly two thousand years ago, the Roman philosopher Cicero cautioned “It is the nature of man to err”. It is an unequivocal fact that whenever men and women are involved in an activity, human error will occur at some point. It is clear that aircraft maintenance engineering depends on the competence of engineers. Many of the examples presented in Chapter 1 “Incidents Attributable to Human Factors / Human Error” and throughout the rest of this document highlight errors that aircraft maintenance engineers have made which have contributed to aircraft incidents or accidents. In the past, aircraft components and systems were relatively unreliable. Modern aircraft by comparison are designed and manufactured to be highly reliable. As a consequence, it is more common nowadays to hear that an aviation incident or accident has been caused by “human error”.

The following quotation illustrates how aircraft maintenance engineers play a key role in keeping modern aircraft reliable: “Because civil aircraft are designed to fly safely for unlimited time provided defects are detected and repaired, safety becomes a matter of detection and repair rather than one of aircraft structure failure. In an ideal system, all defects which could affect flight safety will have been predicted in advance, located positively before they become dangerous, and eliminated by effective repair. In one sense, then, we have changed the safety system from one of physical defects in aircraft to one of errors in complex human-centred systems” The rest of this chapter examines some of the various ways in which human error has been conceptualized. It then considers the likely types of error that occur during aircraft maintenance and the implications if these errors are not spotted and corrected. Finally, means of managing human error in aircraft maintenance are discussed. In his book “Human Error”, Professor James Reason defines error as follows: “Error will be taken as a generic term to encom all those occasions in which a planned sequence of mental or physical activities fails to achieve its intended outcome, and when these failures cannot be attributed to the intervention of some chance agency”.

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9.3.1 ERROR MODELS AND THEORIES To appreciate the types of error that it is possible to make, researchers have looked at human error in a number of ways and proposed various models and theories. These attempt to capture the nature of the error and its characteristics. To illustrate this, the following models and theories will be briefly highlighted: design- versus operator-induced errors variable versus constant errors reversible versus irreversible errors slips, lapses and mistakes skill-, rule- and knowledge-based behaviours and associated errors the ‘Swiss Cheese Model’ DESIGN VERSUS OPERATOR-INDUCED ERRORS In aviation, emphasis is often placed upon the error(s) of the front line operators, who may include flight crew, air traffic controllers and aircraft maintenance engineers. However, errors may have been made before an aircraft ever leaves the ground by aircraft designers. This may mean that, even if an aircraft is maintained and flown as it is designed to be, a flaw in its original design may lead to operational safety being compromised. Alternatively, flawed procedures put in place by airline, maintenance organization or air traffic control management may also lead to operational problems. It is common to find when investigating an incident or accident that more than one error has been made and often by more than one person. It may be that, only when a certain combination of errors arises and error ‘defences’ breached (see the ‘Swiss Cheese Model’) will safety be compromised.

VARIABLE VERSUS CONSTANT ERRORS In his book “Human Error”, Professor Reason discusses two types of human error: variable and constant. It can be seen in Figure 3.1 that variable errors in (A) are random in nature, whereas the constant errors in (B) follow some kind of consistent, systematic (yet erroneous) pattern. The implication is that constant errors may be predicted and therefore controlled, whereas variable errors cannot be predicted and are much harder to deal with. If we know enough about the nature of the task, the environment it is performed in, the mechanisms governing performance, and the nature of the individual, we have a greater chance of predicting an error.

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However, it is rare to have enough information to permit accurate predictions; we can generally only predict along the lines of “re-assembly tasks are more likely to incur errors than dismantling tasks”, or “an engineer is more likely to make an error at 3 a.m., after having worked 12 hours, than at 10 a.m. after having worked only 2 hours”. It is possible to refine these predictions with more information, but there will always be random errors or elements which cannot be predicted.

REVERSIBLE VERSUS IRREVERSIBLE ERRORS Another way of categorizing errors is to determine whether they are reversible or irreversible. The former can be recovered from, whereas the latter typically cannot be. For example, if a pilot miscalculates the fuel he should carry, he may have to divert to a closer airfield, but if he accidentally dumps his fuel, he may not have many options open to him. A well designed system or procedure should mean that errors made by aircrft maintenance engineers are reversible. Thus, if an engineer installs a part incorrectly, it should be spotted and corrected before the aircraft is released back to service by supervisory procedures in place.

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SLIPS, LAPSES AND MISTAKES Reason highlights the notion of ‘intention’ when considering the nature of error, asking the questions: Were the actions directed by some prior intention Did the actions proceed as planned? Did they achieve their desired end? Reason then suggests an error classification based upon the answers to these questions as shown in Figure 3.2. The most well-known of these are slips, lapses and mistakes. Slips typically occur at he task execution stage, lapses at the storage (memory) stage and mistakes at the planning stage. Slips can be thought of as actions not carried out as intended or planned, e.g. ‘transposing digits when copying out numbers, or misordering steps in a procedure. Lapses are missed actions and omissions, i.e. when somebody has failed to do something due to lapses of memory and/or attention or because they have forgotten something, e.g. forgetting to replace an engine cowling. Mistakes are a specific type of error brought about by a faulty plan/intention, i.e. somebody did something believing it to be correct when it was, in fact, wrong, e.g. an error of judgment such as mis-selection of bolts when fitting an aircraft windscreen.

Violations sometimes appear to be human errors, but they differ from slips, lapses and mistakes because they are deliberate ‘illegal’ actions, i.e. somebody did something knowing it to be against the rules (e.g. deliberately failing to follow proper procedures). Aircraft maintenance engineers may consider that a violation is well intentioned, i.e. ‘cutting corners’ to get a job done on time. However, procedures must be followed appropriately to help safeguard safety.

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SKILL-, RULE- AND KNOWLEDGE-BASED BEHAVIOURS AND ASSOCIATED ERRORS The behaviour of aircraft maintenance engineers can be broken down into three distinct categories: skill-based, rule-based and knowledge-based behaviour. Each of these behaviour types have specific errors associated with them. Examples of skill-based errors are action slips, environmental capture and reversion. Action slips as the name implies are the same as slips, i.e. an action not carried out as intended. The example given in Figure 3.3 may consist of an engineer realizing he needs a certain wrench to complete a job but, because he is distracted by a colleague, picks up another set to the wrong torque and fails to notice that he has tightened the bolts incorrectly. Environmental capture may occur when an engineer carries out a certain task very frequently in a certain location. Thus, an engineer used to carrying out a certain maintenance adjustment on an Airbus A300, may inadvertently carry out this adjustment on the next A300 he works on, even if it is not required (and he has not made a conscious decision to operate the skill). Reversion can occur once a certain pattern of behaviour has been established, primarily because it can be very difficult to abandon or unlearn it when it is no longer appropriate. Thus, an engineer may accidentally carry out a procedure that he has used for

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years, even though it has been recently revised. This is more likely to happen when people are not concentrating or when they are in a stressful situation. Green et al define these: “Skill-based behaviours are those that rely on stored routines or motor programs that have been learned with practice and may be executed without conscious thought. Rulebased behaviours are those for which a routine or procedure has been learned. The components of a rule-based behaviour may comprise a set of discrete skills. Knowledgebased behaviours are those for which no procedure has been established. These require the [aircraft maintenance engineer] to evaluate information, and then use his knowledge and experience to formulate a plan for dealing with the situation.” Rule-based behaviour is generally fairly robust and this is why the use of procedures and rules is emphasized in aircraft maintenance. However, errors here are related to the use of the wrong rule or procedure. For example, an engineer may misdiagnose a fault and thus apply the wrong procedure, thus not clearing the fault. Errors here are also sometimes due to faulty recall of procedures. For instance, not ing the correct sequence when performing a procedure. Errors at the knowledge-based performance level are related to incomplete or incorrect knowledge or interpreting the situation incorrectly. An example of this might be when an engineer attempts an unfamiliar repair task and assumes he can ‘work it out’. Once he has set out in this way, he is likely to take more notice of things that suggest he is succeeding in his repair, while ignoring evidence to the contrary (known as confirmation bias).

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THE ‘SWISS CHEESE MODEL’ In his research, Reason has highlighted the concept of ‘defences’ against human error within an organization, and has coined the notion of ‘defences in depth’. Examples of defences are duplicate inspections, pilot pre-flight functional checks, etc., which help prevent to ‘trap’ human errors, reducing the likelihood of negative consequences. It is when these defences are weakened and breached that human errors can result in incidents or accidents. These defences have been portrayed diagrammatically, as several slices of Swiss cheese (and hence the model has become known as Professor Reason’s “Swiss cheese” model) (see Figure 3.4). Some failures are latent, meaning that they have been made at some point in the past and lay dormant. This may be introduced at the time an aircraft was designed or may be associated with a management decision. Errors made by front line personnel, such as aircraft maintenance engineers, are ‘active’ failures. The more holes in a system’s defences, the more likely it is that errors result in incidents or accidents, but it is only in certain circumstances, when all holes ‘line up’, that these occur. Usually, if an error has breached the engineering defences, it reaches the flight operations defences (e.g. in flight warning) and is detected and handled at this stage. However, occasionally in aviation, an error can breach all the defences (e.g. a pilot ignores an in flight warning, believing it to be a false alarm) and a catastrophic situation ensues.

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9.3.2 TYPES OF ERROR IN MAINTENANCE TASKS As aircraft maintenance engineers are human, errors in the industry are inevitable. Any maintenance task performed on an aircraft is an opportunity for human error to be introduced. Errors in aircraft maintenance engineering tend to take two specific forms: i)

an error that results in a specific aircraft problem that was not there before the maintenance task was initiated;

ii)

an error that results in an unwanted or unsafe condition remaining undetected while performing a maintenance task designed to detect aircraft problems, i.e. something is missed.

Examples of errors highlighted in the above (i) are incorrect installation of line replaceable units, failure to remove a protective cap from a hydraulic line before reassembly or damaging an air duct used as a foothold while gaining access to perform a task. Examples of errors in (ii) are a structural crack unnoticed during a visual inspection task or a faulty avionics box that remains on the aircraft because incorrect diagnosis of the problem led to removal of the wrong box. ERRORS DURING REGULAR AND LESS FREQUENT MAINTENANCE TASKS A large proportion of maintenance tasks are fairly routine, such as regular, periodic checks on aircraft. Thus, engineers will use a certain set of procedures relatively frequently and, as noted in the previous section, slips and lapses can occur when carrying out procedures in the busy hangar or line environment. “Repetitive Tasks” noted that engineers will often become so accustomed to doing a regular, often repeated task, that they will dispense with written guidance altogether. It would be unrealistic and unnecessarily time consuming to expect them to constantly refer to familiar guidance material. However, errors may occur if they do not keep up-to-date with any changes that occur to these frequently used procedures. These routine tasks are also prone to complacency, environmental capture and rule-based errors. When undertaking less frequently performed tasks, there is the possibility of errors of judgment. If the engineer does not familiarize or re-familiarise himself properly with what needs to be done, he may mistakenly select the wrong procedure or parts.

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9.3.3 VIOLATIONS It is an unfortunate fact of life that violations occur in aviation maintenance. Most stem from a genuine desire to do a good job. Seldom are they acts of vandalism or sabotage. However, they represent a significant threat to safety as systems are designed assuming people will follow the procedures. There are four types of violations: Routine violations Situational violations Optimising violations Exceptional violations Routine violations are things which have become ‘the normal way of doing something’ within the person’s work group (e.g. a maintenance team). They can become routine for a number of reasons: Engineers may believe that procedures may be over prescriptive and violate them to simplify a task (cutting corners), to save time and effort. Examples of routine violations are not performing an engine run after a borescope inspection (“it never leaks”), or not changing the ‘O’ seals on the engine gearbox drive pad after a borescope inspection (“they are never damaged”). Situational violations occur due to the particular factors that exist at the time, such as time pressure, high workload, unworkable procedures, inadequate tooling, poor working conditions. These occur often when, in order to get the job done, engineers consider that a procedure cannot be followed. An example of a situational violation is an incident which occurred where the door of a B747 came open in-flight. An engineer with a tight deadline discovered that he needed a special jig to drill off a new door torque tube. The jig was not available, so the engineer decided to drill the holes by hand on a pillar drill. If he had complied with the maintenance manual he could not have done the job and the aircraft would have missed the service. Optimising violations involve breaking the rules for ‘kicks’. These are often quite unrelated to the actual task. The person just uses the opportunity to satisfy a personal need. An example of an optimising violation would be an engineer who has to go across the airfield and drives there faster than permitted Exceptional violations are typified by particular tasks or operating circumstances that make violations inevitable, no matter how well intentioned the engineer might be.

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Time pressure and high workload increase the likelihood of all types of violations occurring. People weigh up the perceived risks against the perceived benefits; unfortunately the actual risks can be much higher. ERRORS DUE TO INDIVIDUAL PRACTICES AND HABITS Where procedures allow some leeway, aircraft maintenance engineers often develop their own strategies or preferred way of carrying out a task. Often, a ‘good’ rule or principle is one that has been used successfully in the past. These good rules become ‘rules of thumb’ that an engineer might adopt for day-to-day use. Problems occur when the rule or principle is wrongly applied. For example, aircraft pipe couplings are normally right hand threads but applying this ‘normally good rule’ to an oxygen pipe (having a different thread) could result in damage to the pipe. Also, there can be dangers in applying rules based on previous experience if, for example, design philosophy differs, as in the case of Airbus and Boeing. This may have been a factor in an A320 locked spoiler incident, where subtle differences between the operation of the spoilers on the A320 and those of the B767 (with which the engineers were more familiar) meant that actions which would have been appropriate on the B767 were inappropriate in the case of the A320. In addition, engineers may pick up some ‘bad rules’, leading to bad habits during their working life, as a driver does after ing his driving test. An example of applying a bad rule is the British Rail technician in the Clapham train accident who had acquired the practice of bending back old wires rather than cutting them off and insulating them. ERRORS ASSOCIATED WITH VISUAL INSPECTION There are also two particular types of error which are referred to particularly in the context of visual inspection, namely Type 1 errors and Type 2 errors. A Type 1 error occurs when a good item is incorrectly identified as faulty; a Type 2 error occurs when a faulty item is missed. Type 1 errors are not a safety concern per se, except that it means that resources are not being used most effectively, time being wasted on further investigation of items which are not genuine faults. Type 2 errors are of most concern since, if the fault (such as a crack) remains undetected, it can have serious consequences (as was the case in the Aloha accident, where cracks remained undetected).

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REASON’S STUDY OF AVIATION MAINTENANCE ENGINEERING Reason analyzed the reports of 122 maintenance incidents occurring within a major airline over a 3 year period. He identified the main causes as being: Omissions (56%) Incorrect installation (30%) Wrong parts (8%) Other (6%) It is likely that Reason’s findings are representative for the aircraft maintenance industry as a whole. Omissions can occur for a variety of reason, such as forgetting, deviation from a procedure (accidental or deliberate), or due to distraction. The B737 double engine oil loss incident, in which the HP rotor drive covers were not refitted is an example of omission. Incorrect installation is unsurprising, as there is usually only one way in which something can be taken apart but many possible ways in which it can be reassembled. Reason illustrates this with a simple example of a bolt and several nuts (see Figure 3.5), asking the questions: (a) how many ways can this be disassembled? (the answer being 1) and, (b) how many ways can it be reassembled? (the answer being about 40,000, excluding errors of omission!)

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9.3.4 IMPLICATIONS OF ERRORS (I.E. ACCIDENTS) In the worst cases, human errors in aviation maintenance can and do cause aircraft accidents. However, as portrayed in Figure 3.6, accidents are the observable manifestations of error. Like an iceberg which has most of its mass beneath the water line, the majority of errors do not result in actual accidents. Thankfully, most errors made by aircraft maintenance engineers do not have catastrophic results. This does not mean that this might not be the result should they occur again. Errors that do not cause accidents but still cause a problem are known as incidents. This subject was introduced at the beginning “Incidents Attributable to Human Factors / Human Error”, which gave examples of aviation incidents relating to aircraft maintenance errors. Some incidents are more high profile than others, such as errors causing significant in-flight events that, fortuitously, or because of the skills of the pilot, did not become accidents. Other incidents are more mundane and do not become serious because of defences built into the maintenance system. However, all incidents are significant to the aircraft maintenance industry, as they may warn of a potential future accident should the error occur in different circumstances. As a consequence, all maintenance incidents have to be reported to the UK Civil Aviation Authority Mandatory Occurrence Reporting Scheme (MORS). These data are used to disclose trends and, where necessary, implement action to reduce the likelihood or criticality of further errors. In the UK, the Confidential Human Factors Incident Reporting Programme (CHIRP) scheme provides an alternative reporting mechanism for individuals who want to report safety concerns and incidents confidentially. It is likely that the greatest proportions of errors made by aircraft maintenance engineers are spotted almost immediately they are made and corrected. The engineer may detect his own error, or it may be picked up by colleagues, supervisors or quality control. In

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these cases, the engineer involved should (it is hoped) learn from his error and therefore (it is hoped) be less likely to make the same error again. When an error occurs in the maintenance system of an airline, the engineer who last worked on the aircraft is usually considered to be ‘at fault’. The engineer may be reprimanded, given remedial training or simply told not to make the same error again. However, blame does not necessarily act as a positive force in aircraft maintenance: it can discourage engineers from ‘coming clean’ about their errors. They may cover up a mistake or not report an incident. It may also be unfair to blame the engineer if the error results from a failure or weakness inherent in the system which the engineer has accidentally discovered (for example, a latent failure such as a poor procedure drawn up by an aircraft manufacturer - possibly an exceptional violation).

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The UK Civil Aviation Authority has stressed in Airworthiness Notice No. 71 (Issue 1, 20 March 2000) that it “seeks to provide an environment in which errors may be openly investigated in order that the contributing factors and root causes of maintenance errors can be addressed”. To facilitate this, it is considered that an unpremeditated or inadvertent lapse should not incur any punitive action, but a breach of professionalism may do so (e.g. where an engineer causes deliberate harm or damage, has been involved previously in similar lapses, attempted to hide their lapse or part in a mishap, etc.).

9.3.5 AVOIDING AND MANAGING ERRORS Whilst the aircraft maintenance engineering industry should always strive towards ensuring that errors do not occur in the first place, it will never be possible to eradicate them totally. Therefore all maintenance organizations should aim to ‘manage’ errors.There is nothing new about trying to manage error. All responsible organizations involved in hazardous operations have long employed a wide variety of error management (EM) measures. In maintenance organizations, these include: Selection training and retraining work planning job cards tags and reminders shift handover procedures licence-to-work systems human resource management licensing and certification

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checking and sign-offs technical and quality audits procedures, manuals, rules and regulations disciplinary procedures Total Quality Management (TQM).

These techniques have evolved over many decades. Though some are tried and tested, they have collectively failed to prevent a steady rise in maintenance-related errors. Their limitations include being piecemeal rather than principled, reactive rather than proactive, and fashion-driven rather than theory-driven. They also ignore the substantial developments that have occurred over the last 20 years in understanding the nature and varieties of human error. This brief discussion sets out the fundamental principles of error management. The aim is to provide a concise summary of the error management philosophy. Some readers with very practical turn of mind may shy away from the term 'philosophy’. But all management depends essentially upon what Earl Wiener has termed the 'Four P's': philosophy, policy, procedures and practices. In the case of error management, philosophy is worth at least double the value of each of the other three. Without a unifying set of guiding principles, our efforts will have but a small chance of success. THE PRINCIPLES OF ERROR MANAGEMENT Human Error is both universal and inevitable Human error is not a moral issue. The consequences of errors may be undesirable, even destructive, but making them is as much a part of human life as breathing and sleeping. We include here violations, which are rarely malicious acts and are often well intentioned. Human fallibility can be moderated, but it can never be eliminated. Not should it be. Errors are, not Intrinsically Bad Success and failure spring from the same psychological roots. Errors are fundamentally useful and adaptive things. We are error-guided creatures. Errors mark the boundaries of the path towards successful action just as landing lights define the edges of a runway. Without them, we could neither learn nor acquire the skills that are essential to safe and efficient work. You cannot Change the Human Condition, but You can Change the Conditions in which Humans Work The problem with errors is not the psychological processes that shape them, but the man-made and sometimes unforgiving workplaces that exist within complex systems. There

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are two parts to an error: a mental state and a situation. States of mind like moments of inattention or occasional forgetfulness are givens, but situations are not. And situations vary enormously in their capacity for provoking unwanted actions. Identifying these error traps and recognizing their characteristics are essential preliminaries to effective error management. The Best People can make, the Worst Mistakes A common belief is that a few inept individuals are responsible for most of the errors. If this were the case, the solution to the error problem would be relatively simple: identify these people and then retrain them, sack them or promote them out of harm's way. But the record suggests that the reality is quite different. Some of the world's worst maintenance-related accidents have been due to errors committed by highly experienced people with 30-year blameless records. Errors can strike anywhere at any time. No one is immune. And it is also the case that the best people often occupy the most responsible positions so that their errors can have the greatest impact upon the system at large. People cannot easily avoid those Actions they did not intend to commit Blaming people for their errors is emotionally satisfying but remedially useless. Moral judgments are only appropriate when the actions go as intended and the intention is reprehensible. Blame and punishment make no sense at all when the intention is a good one, but the actions do not go as planned. We, should not, however, confuse the issues of blame and ability. Everyone ought to be able for his or her errors. If the error maker does not acknowledge the error and strive to avoid its recurrence, then no lesson has been learned and little or nothing gained from the experience. Errors are Consequences rather than Causes The natural human tendency after a bad event is to track back in time to the first deviant human action and call it the cause. We then go on to say that Person X caused the event and punish him or her accordingly - often in proportion to the extent of the damage or injury. This may be appropriate in societies that operate by the 'eye for an eye' principle, but it is totally out of place in maintenance organizations in which accidents arise from the complex interaction of many different factors and where the primary aim of any subsequent inquiry should be to strengthen the system's defences. From this perspective, errors are best regarded as consequences rather than causes. Just like the bad event, errors have a history. Each is the product of a chain of events that involves people, teams, tasks, workplaces and organizations. Discovering an error is the beginning of the search for causes not the end. Only by understanding the circumstances that give rise to them can we hope to limit the chances of their recurrence.

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Many Errors Fall into Recurrent Patterns Errors can arise from either a unique combination of circumstances, or from work situations that recur many times in the course of maintenance-related activities. The former are random errors-in the sense that their occurrence is very hard to foresee - while the latter are systematic or recurrent errors. As we discussed earlier, more than half of the human factors incidents in maintenance are recognized as having occurred before, often many times. We also observed that certain aspects of maintenance, particularly reassembly or reinstallations, commonly give rise to particular kinds of errors, notably omissions-leaving out essential steps in a sequence or failing to remove unwanted objects on completion. Another frequent group of errors involves miscommunication or lack of communication both within and between maintenance teams or shifts. Targeting these recurrent error types is the most effective way of deploying limited EM resources. Safety-significant Errors can occur at all Levels of the System Making errors is not the monopoly of those who get their hands dirty. Managers often think that error reduction and error containment is something that applies exclusively to the workforce, the people at the 'sharp end'. A general rule of thumb, however, is that the higher up the organization an individual is, the more dangerous are his or her errors. Error management techniques need to be applied across the whole system. Error Management is about Managing the Manageable One of the commonest errors in error management is striving to control the uncontrollable. Most obviously, this entails trying to change those aspects of human nature that are virtually unchangeable - that is, our proneness to distraction, preoccupation, moments of inattention and occasional forgetting. And, when these attempts fail (as they surely will), the next mistake is to try to shift blame and responsibility away from the company at large and on to those unfortunates known to have made errors. It is the prevalence of these misguided approaches that has led, in large part, to the steady increase in public awareness of maintenance - related errors. Situations, and even systems, are manageable; human nature - in its broadest sense - is not. Most of the enduring solutions to human factors problems involve technical, procedural and organizational measures rather than purely psychological ones. The problem is that blaming individuals rather than reforming systems has its roots deep In human nature. Such a response may offer some short-term emotional satisfaction, but it provides little or nothing in the wav of improvements. An important step in effective error management is to recognize the existence of this fundamental attribution error psychologists call this person-blaming tendency) and to fight against it. Error management is about Making Good People Excellent The assumption is often made that error management is a process for making a few error-prone people better. This is not the case. The principal aim of EM to is to make well

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trained and highly motivated excellent. Excellence in any professional activity has two crucial elements: technical skills and mental skills. Both need to be acquired through training and practice. Several studies have shown the mental element is at least as important as the possession of requisite technical skills. The mental element involves a number of different components. Among the most important of these is mental readiness. Excellent performers routinely prepare themselves for potentially challenging activities by mentally rehearsing their responses to a variety of imagined situations. To do this effectively requires an understanding of the ways in which a task can go wrong. In the case of maintenancerelated tasks, this means having an awareness of the varieties of human error and the situations that provoke them. Self-knowledge of this kind is at least as important as anticipating the ways in which a piece of equipment can fail. Maintenance staff needs to be trained in two ways. First, they need to be informed about the ways in which human performance problems can arise and to be aware of their recurrent patterns. In other words, they need to be familiar with the fundamentals of human performance and the verities of error. Second, they must acquire the skill of mental preparedness. That is, they should be trained to approach each task by mentally rehearsing the ways in which they and their colleagues could go wrong. This not only alerts them to risks of error-provoking situations, but also allows them to plan how they might detect and recover these errors before they cause harm. Improving the skills of error detection is at least as important as making people aware of how errors arise in the first place. There is no One Best Way This principle applies in two ways. First, there is no one best technique for error management. Different types of human factors problems occur at different levels of the organization and require different management techniques. Mistakes and violations, for example, have different underlying mechanisms. Mistakes are mainly information processing problems, while violations have a large social and motivational component. Effective or comprehensive error management involves targeting different countermeasures at different parts of the company: the person, the team, the task, the workplace and the organization as a whole. Second, there is no one best package of F.M measures. Different organizational re the 'mixing and matching' of different combinations of techniques.Methods that work well in one company can fail in another, and conversely. This is why these principles are so important. There are many ways of achieving principled reduction and containment of human factors problem is up to each organization to choose or to develop the methods, work best for them. It is often better to devise own methods, or at least to adapt existing techniques to suit local needs. People are often more likely 'buy in' to home-grown measures than to ones that have been imported from elsewhere. So long as the basic principles are understood and followed, there are many different ways of achieving effective EM-and most of them have yet to be devised.

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Effective EM aims at Continuous Reform rather than Local Fixes There is always a strong temptation to focus upon the last few incidents and to try to make sure that they, at least, will not happen again. This tendency is further strengthened by the engineer's natural inclination to solve specific concrete problems. But trying to prevent the recurrence of individual errors is like swatting mosquitoes. You kill one and the rest keep coming to bite you. As pointed out earlier, the only way to solve the mosquito problem is to drain the swamps in which they breed. In the case of maintenance errors, this means reforming the condition under which people work as well as strengthening and extending the system's defences. Reform of the system as a whole must be a continuous process whose aim is to reduce and contain whole groups of errors rather than single blunders. The Management of Error Management EM has three components: error reduction, error containment and managing these activities so that they continue to work effectively. Of these three, the latter is by far the most challenging and difficult task. For EM to have a lasting effect, it needs to be continuously monitored and adjusted to changing conditions. It is simply not possible to order in a package of EM measures, implement them and then expect them to work without any further attention. You cannot just put them in place and then tick them off as another job completed. Here, the bulk of the effort lies in the process rather than the product. In an important sense, the process - the continuous striving toward system reform - is the product. SUMMARIZING THE EM PRINCIPLES Human error is both universal and inevitableErrors are not intrinsically bad. You cannot change the human condition, but you can change the conditions in which humans work. The best people can make the worst mistakes. People cannot easily avoid those actions they did not intend to commit. Errors are consequences rather than causes. Many errors fall into recurrent patterns. Safety-significant errors can occur at all levels of the system. Error management is about managing the manageable. Error management is about making good people excellent. There is no one best way. Effective error management aims at continuous reform rather than local fixes. Managing error management is the most challenging and difficult part of the EM process.

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9.3.6 HUMAN RELIABILITY The term "human reliability" is usually defined as the probability that a person will correctly performs some system-required activity during a given time period (if time is a limiting factor) without performing any extraneous activity that can degrade the system. The historical background for the development of the set of methods that are commonly referred to as Human Reliability Analysis (HRA) was the need to describe incorrect human actions in the context of Probabilistic Risk Assessment (PRA) or Probabilistic Safety Analysis (PSA). The premises for HRA were, and are, therefore that it must function within the constraints defined by PRA/PSA, and specifically that it can produce the human action probabilities that are needed by the PRA/PSA. HUMAN ERROR PROBABILITIES AND PERFORMANCE SHAPING FACTORS The practice of HRA goes back to the early 1960s, but the majority of HRA methods were developed in the middle of the 1980s – mainly as a consequence of the concern caused by the accident in 1979 at the nuclear power plant at Three Mile Island. Partly due to the conditions under which it was developed, HRA methods from the beginning used procedures similar to those employed in conventional reliability analysis. The main difference was that human task activities were substituted for equipment failures and that modifications were made to for the greater variability and interdependence of human performance as compared with that of equipment. In the search for a way of describing and understanding the failure of human actions, several classes of models have been used. In brief, HRA methods seem to include one of the following types of operator model. Behavioural or human factors, models that focus on simple manifestations (error modes). The error modes are usually described in of omissions, commissions, and extraneous actions and the methods aim at deriving the probability that a specific manifestation will occur. Since causal models are either very simple or non-existent, the theoretical basis for predicting performance failures is inadequate. Behavioural models are therefore also weak in ing for the influence of context. Information processing models that focus on internal "mechanisms" for, e.g., decision making or reasoning. The methods aim at explaining the flow of causes and effects through the models. Causal models are therefore often complex, but with limited predictive power, and little concern for quantification. Error types typically refer to the cause as much as the manifestation (e.g., slips, lapses, mistakes, violations), or to the malfunctioning of a hypothetical information processing function. Context is not considered explicitly, at most in of the input to the operator, and information processing models are better suited for retrospective analysis than for predictions.

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Cognitive models that focus on the relation between error modes and causes, where the latter refer to the socio-technical environment as a whole. Unlike information processing models, cognitive models are simple and context is explicitly represented. Cognition is the reason why performance is efficient - and why it is sometimes limited - and the operator is seen as not only responding to events but also as acting in anticipation of future developments. Cognitive models are well suited for both predictions and retrospective analyses.

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MODULE 9

HUMAN FACTORS

SUB MODULE 9.4

HUMAN PERFORMANCE & LIMITATIONS

Page No i




Page No ii






CONTENTS 9.4 HUMAN PERFORMANCE & LIMITATIONS .......................................

4-1

Human Performance as Part of the Maintenance Engineering System

4-1

9.4.1 Vision............................................................................................

4-2

The Basic Function of the Eye ...........................................................

4-2

Vision and the Aircraft Maintenance Engineer ................................

4-8

9.4.2 Hearing .........................................................................................

4-9

The Basic Function of the Ear ...........................................................

4-9

Hearing Impairment ..........................................................................

4-11

Hearing Protection ............................................................................

4-12

Hearing and the Aircraft Maintenance Engineer ..............................

4-12

9.4.3 Information Processing ................................................................

4-13

An Information Processing Model ....................................................

4-13

Sensory Receptors and Sensory Stores ............................................

4-13

9.4.4 Attention and Perception ............................................................

4-14

Attention and Perception: How does it work? .................................

4-15

Decision Making ................................................................................

4-17

9.4.5 Situation Awareness ....................................................................

4-17

9.4.6 Memory........................................................................................

4-18

Motor Programmes ..........................................................................

4-19

Decision Making, Memory, and Motor Programmes .......................

4-20

9.4.7 Claustrophobia and Physical Access ............................................

4-21

Fear of Heights ..................................................................................

4-22

9.4.8 Motivation....................................................................................

4-23

Maslow’s Hierarchy of Needs ...........................................................

4-23

De-motivation ...................................................................................

4-25

9.4.9 Fitness / Health ............................................................................

4-26

9.4.10 Stress ..........................................................................................

4-28

Stress: Domestic and Work Related .................................................

4-28

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Causes and Symptoms ......................................................................

4-29

Stress Management ..........................................................................

4-30

9.4.11 Workload Management .............................................................

4-31

9.4.12 Fatigue .......................................................................................

4-32

9.4.13 Alcohol, Medication and Drugs..................................................

4-33

Alcohol ..............................................................................................

4-33

Medication ........................................................................................

4-34

Drugs .................................................................................................

4-35

9.4.14 Physical Work .............................................................................

4-35

Planning ............................................................................................

4-35

Physical Tasks ....................................................................................

4-36

9.4.15 Repetitive Tasks / Complacency ................................................

4-37

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Page No v






9.4 HUMAN PERFORMANCE & LIMITATIONS The intention of this chapter is to provide an overview of those key physical and mental human performance characteristics which are likely to affect an aircraft maintenance engineer in his working environment, such as his vision, hearing, information processing, attention and perception, memory, judgment and decision making.

HUMAN PERFORMANCE AS PART OF THE MAINTENANCE ENGINEERING SYSTEM Just as certain mechanical components used in aircraft maintenance engineering have limitations, engineers themselves have certain capabilities and limitations that must be considered when looking at the maintenance engineering ‘system’. For instance, rivets used to attach aluminum skin to a fuselage can withstand forces that act to pull them apart. It is clear that that these rivets will eventually fail if enough force is applied to them. While the precise range of human capabilities and limitations might not be as welldefined as the performance range of mechanical or electrical components, the same principles apply in that human performance is likely to degrade and eventually ‘fail’ under certain conditions (e.g. stress). Mechanical components in aircraft can, on occasion, suffer catastrophic failures. Man, can also fail to function properly in certain situations. Physically, humans become fatigued, are affected by the cold, can break bones in workplace accidents, etc. Mentally, humans can make errors, have limited perceptual powers, can exhibit poor judgment due to lack of skills and knowledge, etc. In addition, unlike mechanical components, human performance is also affected by social and emotional factors. Therefore failure by aircraft maintenance engineers can also be to the detriment of aircraft safety. The aircraft engineer is the central part of the aircraft maintenance system. It is therefore very useful to have an understanding of how various parts of his body and mental processes function and how performance limitations can influence his effectiveness at work.

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9.4.1 VISION THE BASIC FUNCTION OF THE EYE In order to understand vision, it is useful first to know a little about the anatomy of the eye (see Figure 4.1). The basic structure of the eye is similar to a simple camera with an aperture (the iris), a lens, and a light sensitive surface (the retina). Light enters the eye through the cornea, then es through the iris and the lens and falls on the retina. Here the light stimulates the light-sensitive cells on the retina (rods and cones) and these small electrical impulses by way of the optic nerve to the visual cortex in the brain. Here, the electrical impulses are interpreted and an image is perceived. THE CORNEA The cornea is a clear ‘window’ at the very front of the eye. The cornea acts as a fixed focusing device. The focusing is achieved by the shape of the cornea bending the incoming light rays. The cornea is responsible for between 70% and 80% of the total focusing ability (refraction) of the eye. THE IRIS AND PUPIL The iris (the coloured part of the eye) controls the amount of light that is allowed to enter the eye. It does this by varying the size of the pupil (the dark area in the centre of the iris). The size of the pupil can be changed very rapidly to cater for changing light levels. The amount of light can be adjusted by a factor of 5:1. THE LENS After ing through the pupil, the light es through the lens. Its shape is changed by the muscles (cillary muscles) surrounding it which results in the final focusing adjustment to place a sharp image onto the retina. The change of shape of the lens is called accommodation. In order to focus clearly on a near object, the lens is thickened. To focus on a distant point, the lens is flattened. The degree of accommodation can be affected by factors such as fatigue or the ageing process. THE RETINA The retina is located on the rear wall of the eyeball. It is made up of a complex layer of nerve cells connected to the optic nerve. Two types of light sensitive cells are found in the retina - rods and cones. The central area of the retina is known as the fovea and the receptors in this area are all cones. It is here that the visual image is typically focused. Moving outwards, the cones become less dense and are progressively replaced by rods, so that in the periphery of the retina, there are only rods.

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At the point at which the optic nerve s the back of the eye, a ‘blind spot’ occurs. This is not evident when viewing things with both eyes (binocular vision), since it is not possible for the image of an object to fall on the blind spots of both eyes at the same time. Even when viewing with one eye (monocular vision), the constant rapid movement of the eye (saccades) means that the image will not fall on the blind spot all the time. It is only when viewing a stimulus that appears very fleetingly (e.g. a light flashing), that the blind spot may result in something not being seen. In maintenance engineering, tasks such as close visual inspection or crack detection should not cause such problems, as the eye or eyes move across and around the area of interest (visual scanning).

FACTORS AFFECTING CLARITY OF SIGHT The eye is very sensitive in the right conditions (e.g. clear air, good light, etc.). In fact, the eye has approximately 1.2 million nerve cells leading from the retinas to the area of the brain responsible for vision, while there are only about 50,000 from the inner ears - making the eye about 24 times more sensitive than the ear. Before considering factors that can influence and limit the performance of the eye, it is necessary to describe visual acuity. When a person is tired accommodation is reduced, resulting in less sharp vision (sharpness of vision is known as visual acuity). Cones function in good light and are capable of detecting fine detail and are colour sensitive. This means the human eye can distinguish about 1000 different shades of colour. Rods cannot detect

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colour. They are poor at distinguishing fine detail, but good at detecting movement in the edge of the visual field (peripheral vision). They are much more sensitive at lower light levels. As light decreases, the sensing task is ed from the cones to the rods. This means in poor light levels we see only in black and white and shades of grey. Visual acuity is the ability of the eye to discriminate sharp detail at varying distances. An individual with an acuity of 20/20 vision should be able to see at 20 feet that which the so-called ‘normal’ person is capable of seeing at this range. It may be expressed in meters as 6/6 vision. The figures 20/40 mean that the observer can read at 20 feet what a ‘normal’ person can read at 40 feet. Various factors can affect and limit the visual acuity of the eye. These include:  Physical factors such as:  physical imperfections in one or both eyes (short sightedness, long sightedness)  age  The influence of ingested foreign substances such as:  Drugs  Medication  Alcohol  Cigarettes  Environmental factors such as:  amount of light available  Clarity of the air (e.g. dust, mist, rain, etc.)  Factors associated with object being viewed such as:  size and contours of the object  contrast of the object with its surroundings  relative motion of the object  distance of the object from the viewer  the angle of the object from the viewer

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PHYSICAL FACTORS Long sight - known as Hypermetropia - is caused by a shorter than normal eyeball which means that the image is formed behind the retina (Figure 6). If the cornea and the lens cannot use their combined focusing ability to compensate for this, blurred vision will result when looking at close objects.

Short sight - known as Myopia - is where the eyeball is longer than normal, causing the image to be formed in front of the retina (Figure 4.3). If the accommodation of the lens cannot counteract this then distant objects are blurred.

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OTHER VISUAL PROBLEMS INCLUDE:  Cataracts - clouding of the lens usually associated with ageing  Astigmatism - a misshapen cornea causing objects to appear irregularly shaped  Glaucoma - a build up in pressure of the fluid within the eye which can cause damage to the optic nerve and even blindness  Migraine - severe headaches that can cause visual disturbances Finally as a person grows older, the lens becomes less flexible meaning that it is unable to accommodate sufficiently. This is known as presbyopia and is a form of long sightedness. Consequently, after the age of 40, spectacles may be required for near vision, especially in poor light conditions. Fatigue can also temporarily affect accommodation, causing blurred vision for close work. FOREIGN SUBSTANCES Vision can be adversely affected by the use of certain drugs and medications, alcohol, and smoking cigarettes. With smoking, carbon monoxide which builds up in the bloodstream allows less oxygen to be carried in the blood to the eyes. This is known as hypoxia and can impair rapidly the sensitivity of the rods. Alcohol can have similar effects, even hours after the last drink. ENVIRONMENTAL FACTORS Vision can be improved by increasing the lighting level, but only up to a point as the law of diminishing returns operates. Also, increased illumination could result in increased glare. Older people are more affected by the glare of reflected light than younger people. Moving from an extremely bright environment to a dimmer one has the effect of vision being severely reduced until the eyes get used to less light being available. This is because the eyes have become light adapted. If an engineer works in a very dark environment for a long time, his eyes gradually become dark adapted allowing better visual acuity. This can take about 7 minutes for the cones and 30 minutes for the rods. As a consequence, moving between a bright hanger (or the inside of an aircraft) to a dark apron area at night can mean that the maintenance engineer must wait for his eyes to adjust (adapt). In low light conditions, it is easier to focus if you look slightly to one side of an object. This allows the image to fall outside the fovea and onto the part of the retina which has many rods. Any airborne particles such as dust, rain or mist can interfere with the transmission of light through the air, distorting what is seen. This can be even worse when spectacles are worn, as they are susceptible to getting dirty, wet, misted up or scratched. Engineers who wear lenses (especially hard or gas-permeable types) should take into the advice from their optician associated with the maximum wear time - usually 8 to 12 hours Page No 4-6





and consider the effects which extended wear may have on the eyes, such as drying out and irritation. This is particularly important if they are working in an environment which is excessively dry or dusty, as airborne particles may also affect lens wear. Goggles should be worn where necessary. THE NATURE OF THE OBJECT BEING VIEWED Many factors associated with the object being viewed can also influence vision. We use information from the objects we are looking at to help distinguish what we are seeing. These are known as visual cues. Visual cues often refer to the comparison of objects of known size to unknown objects. An example of this is that we associate small objects with being further away. Similarly, if an object does not stand out well from its background (i.e. it has poor contrast with its surroundings), it is harder to distinguish its edges and hence its shape. Movement and relative motion of an object, as well as distance and angle of the object from the viewer, can all increase visual demands. COLOUR VISION Although not directly affecting visual acuity, inability to see particular colours can be a problem for the aircraft maintenance engineer. Amongst other things, good colour vision for maintenance engineers is important for:  Recognizing components  Distinguishing between wires  Using various diagnostic tools  Recognizing various lights on the airfield (e.g. warning lights) Colour defective vision is usually hereditary, although may also occur as a temporary condition after a serious illness. There are degrees of colour defective vision, some people suffering more than others. Individuals may be able to distinguish between red and green in a well-lit situation but not in low light conditions. Colour defective people typically see the colours they have problems with as shades of neutral grey.

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Ageing also causes changes in colour vision. This is a result of progressive yellowing of the lens, resulting in a reduction in colour discrimination in the blue-yellow range. Colour defective vision and its implications can be a complex area and care should be taken not to stop an engineer from performing certain tasks merely because he suffers from some degree of colour deficient vision. It may be that the type and degree of colour deficiency is not relevant in their particular job. However, if absolutely accurate colour discrimination is critical for a job, it is important that appropriate testing and screening be put in place. Colour-defective vision (normally referred to incorrectly as colour blindness) affects about 8% of men but only 0.5% of women. The most common type is difficulty in distinguishing between red and green. More rarely, it is possible to confuse blues and yellows.

VISION AND THE AIRCRAFT MAINTENANCE ENGINEER It is important for an engineer, particularly one who is involved in inspection tasks, to have adequate vision to meet the task requirements. As discussed previously, age and problems developing in the eye itself can gradually affect vision. Without regular vision testing, aircraft maintenance engineers may not notice that their vision is deteriorating. In the UK, the CAA has produced guidance which states: “A reasonable standard of eyesight is needed for any aircraft engineer to perform his duties to an acceptable degree. Many maintenance tasks require a combination of both distance and near vision. In particular, such consideration must be made where there is a need for the close visual inspection of structures or work related to small or miniature components. The use of glasses or lenses to correct any vision problems is perfectly acceptable and indeed they must be worn as prescribed. Frequent checks should be made to ensure the continued adequacy of any glasses or lenses. In addition, colour discrimination may be necessary for an individual to drive in areas where aircraft maneuver or where colour coding is used, e.g. in aircraft wiring. Organizations should identify any specific eyesight requirement and put in place suitable procedures to address these issues.” Often, airline companies or airports will set the eyesight standards for reasons other than aircraft maintenance safety, e.g. for insurance purposes, or for driving on the airfield. Ultimately, what is important is for the individual to recognize when his vision is adversely affected, either temporarily or permanently and to consider carefully the possible consequences should they continue to work if the task requires good vision.

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9.4.2 HEARING THE BASIC FUNCTION OF THE EAR The ear performs two quite different functions. It is used to detect sounds by receiving vibrations in the air, and secondly, it is responsible for balance and sensing acceleration. Of these two, the hearing aspect is more pertinent to the maintenance engineer, and thus it is necessary to have a basic appreciation of how the ear works. As can be seen in Figure 8, the ear has three divisions: outer ear, middle ear and inner ear. These act to receive vibrations from the air and turn these signals into nerve impulses that the brain can recognize as sounds. OUTER EAR The outer part of the ear directs sounds down the auditory canal, and on to the eardrum. The sound waves will cause the eardrum to vibrate. MIDDLE EAR Beyond the eardrum is the middle ear which transmits vibrations from the eardrum by way of three small bones known as the ossicles, to the fluid of the inner ear. The middle ear also contains two muscles which help to protect the ear from sounds above 80 dB by means of the acoustic or aural reflex, reducing the noise level by up to 20 dB. However, this protection can only be provided for a maximum of about 15 minutes, and does not provide protection against sudden impulse noise such as gunfire. It does explain why a person is temporarily ‘deafened’ for a few seconds after a sudden loud noise. The middle ear is usually filled with air which is refreshed by way of the eustachian tube which connects this part of the ear with the back of the nose and mouth. However, this tube can allow mucus to travel to the middle ear which can build up, interfering with normal hearing.

INNER EAR Unlike the middle ear, the inner ear is filled with fluid. The last of the ossicles in the middle ear is connected to the cochlea. This contains a fine membrane (the basilar membrane) covered in hair-like cells which are sensitive to movement in the fluid. Any vibrations they detect cause neural impulses to be transmitted to the brain via the auditory nerve.

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PERFORMANCE AND LIMITATIONS OF THE EAR The performance of the ear is associated with the range of sounds that can be heard - both in of the pitch (frequency) and the volume of the sound. Volume (or intensity) of sound is measured in decibels (dB). Table 4.1 below shows intensity levels for various sounds and activities.

Activity Rustling of leaves / Whisper

Approximate Intensity level (Decibels) 20

Conversation at 2m

50

Typewriter at 1m

65

Car at 15m

70

Lorry at 15m

75

Power Mower at 2m

90

Propeller aircraft at 300m

100

Jet aircraft at 300m

110

Standing near a propeller aircraft

120

Threshold of pain

140

Immediate hearing damage results

150

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Table 4.1 Typical sound levels for various activities IMPACT OF NOISE ON PERFORMANCE Noise can have various negative effects in the workplace. It can:  be annoying (e.g. sudden sounds, constant loud sound, etc.)  interfere with verbal communication between individuals in the workplace  cause accidents by masking warning signals or messages  be fatiguing and affect concentration, decision making, etc.  damage workers’ hearing (either temporarily or permanently) The amount of vibration detected in the cochlea depends on the volume and pitch of the original sound. The audible frequency range that a young person can hear is typically between 20 and 20,000 cycles per second (or Hertz), with greatest sensitivity at about 3000 Hz. Intermittent and sudden noise is generally considered to be more disruptive than continuous noise at the same level. In addition, high frequency noise generally has a more adverse affect on performance than lower frequency. Noise tends to increase errors and variability, rather than directly affect work rate. HEARING IMPAIRMENT Hearing loss can result from exposure to even relatively short duration noise. The degree of impairment is influenced mainly by the intensity of the noise. Such damage is known as Noise Induced Hearing Loss (NIHL). The hearing loss can be temporary - lasting from a few seconds to a few days - or permanent. Temporary hearing loss may be caused by relatively short exposure to very loud sound, as the hair-like cells on the basilar membrane take time to ‘recover’. With additional exposure, the amount or recovery gradually decreases and hearing loss becomes permanent. Thus, regular exposure to high levels of noise over a long period may permanently damage the hair like cells in the cochlea, leading to irreversible hearing impairment. The UK ‘Noise at Work’ regulations (1989) impose requirements upon employers. They stipulate three levels of noise at which an employer must act: a) 85 decibels (if normal speech cannot be heard clearly at 2 meters), employer must: Page No 4-11





 assess the risk to employees’ hearing  tell the employees about the risks and what precautions are proposed  provide their employees with personal ear protectors and explain their use

b) 90 decibels (if normal speech cannot be heard clearly at 1 meter) employer must:  do all that is possible to reduce exposure to the noise by means other than by providing hearing protection  mark zones where noise reaches the second level and provide recognized signs to restrict entry c) 140 decibels (noise causes pain) The combination of duration and intensity of noise can be described as noise dose. Exposure to any sound over 80 dB constitutes a noise dose, and can be measured over the day as an 8 hour Time Weighted Average sound level (TWA). Permanent hearing loss may occur if the TWA is above the recommended maximum.

HEARING PROTECTION Hearing protection is available, to a certain extent, by using ear plugs or ear defenders. It is good practice to reduce noise levels at source, or move noise away from workers. Often this is not a practical option in the aviation maintenance environment. Hearing protection should always be used for noise, of any duration, above 115 dB. Referring again to Table 1, this means that the aviation maintenance engineer will almost always need to use some form of hearing protection when in reasonably close proximity (about 200 - 300m) to aircraft whose engines are running. PRESBYCUSIS Hearing deteriorates naturally as one grows older. This is known as presbycusis. This affects ability to hear high pitch sounds first, and may occur gradually from the 30’s onwards. When this natural decline is exacerbated by Noise Induced Hearing Loss, it can obviously occur rather sooner.

HEARING AND THE AIRCRAFT MAINTENANCE ENGINEER The UK CAA makes the following recommendations regarding hearing:

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“The ability to hear an average conversational voice in a quiet room at a distance of 2 meters (6 feet) from the examiner is recommended as a routine test. Failure of this test would require an audiogram to be carried out to provide an objective assessment. If necessary, a hearing aid may be worn but consideration should be given to the practicalities of wearing the aid during routine tasks demanded of the individual.” It is very important that the aircraft maintenance engineer understands the limited ability of the ears to protect themselves from damage due to excessive noise. Even though engineers should be given appropriate hearing protection and trained in its use, it is up to individuals to ensure that they actually put this to good use. It is a misconception that the ears get used to constant noise: if this noise is too loud, it will damage the ears gradually and insidiously. Noise levels can be reduced (attenuated) by up to 20 decibels using ear plugs and 40 decibels using ear muffs. However, using ear protection will tend to adversely interfere with verbal communication. Despite this, it must be used consistently and as instructed to be effective.

9.4.3 INFORMATION PROCESSING The previous sections have described the basic functions and limitations of two of the senses used by aircraft maintenance engineers in the course of their work. This section examines the way the information gathered by the senses is processed by the brain. The limitations of the human information processing system are also considered.

AN INFORMATION PROCESSING MODEL Information processing can be represented as a model. This captures the main elements of the process, from receipt of information via the senses, to outputs such as decision making and actions. One such model is shown in Figure 4.5.

SENSORY RECEPTORS AND SENSORY STORES Physical stimuli are received via the sensory receptors (eyes, ears, etc.) and stored for a very brief period of time in sensory stores (sensory memory). Visual information is stored for up to half a second in iconic memory and sounds are stored for slightly longer (up to 2 seconds) in echoic memory. This enables us to a sentence as a sentence, rather than merely as an unconnected string of isolated words, or a film as a film, rather than as a series of disted images.

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9.4.4 ATTENTION AND PERCEPTION Having detected information, our mental resources are concentrated on specific elements - this is attention. Although attention can move very quickly from one item to another, it can only deal with one item at a time. Attention can take the form of:  selective attention  divided attention  focused attention  sustained attention Selective attention occurs when a person is monitoring several sources of input, with greater attention being given to one or more sources which appear more important. A person can be consciously attending to one source whilst still sampling other sources in the background. Psychologists refer to this as the ‘cocktail party effect’ whereby you can be engrossed in a conversation with one person but your attention is temporarily diverted if

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you overhear your name being mentioned at the other side of the room, even though you were not aware of listening in to other people’s conversations. Distraction is the negative side of selective attention. Divided attention is common in most work situations, where people are required to do more than one thing at the same time. Usually, one task suffers at the expense of the other, more so if they are similar in nature. This type of situation is also sometimes referred to as time sharing. Focused attention is merely the skill of focusing one’s attention upon a single source and avoiding distraction. Sustained attention as its name implies, refers to the ability to maintain attention and remain alert over long periods of time, often on one task. Most of the research has been carried out in connection with monitoring radar displays, but there is also associated research which has concentrated upon inspection tasks.Attention is influenced by arousal level and stress. This can improve attention or damage it depending on the circumstances. Perception involves the organization and interpretation of sensory data in order to make it meaningful, discarding non-relevant data, i.e. transforming data into information. Perception is a highly sophisticated mechanism and requires existing knowledge and experience to know what data to keep and what to discard, and how to associate the data in a meaningful manner.

ATTENTION AND PERCEPTION: HOW DOES IT WORK? A proportion of ‘sensed’ data may be lost without being ‘perceived’. An example with which most people are familiar is that of failing to perceive something which someone has said to you, when you are concentrating on something else, even though the words would have been received at the ear without any problem. The other side of the coin is the ability of the information processing system to perceive something (such as a picture, sentence, concept, etc.) even though some of the data may be missing. The danger, however, is that people can fill in the gaps with information from their own store of knowledge or experience, and this may lead to the wrong conclusion being drawn. There are many well-known visual ‘illusions’ which illustrate the limits of human perception. Figure 4.6 shows how the perceptual system can be misled into believing that one line is longer than the other, even though a ruler will confirm that they are exactly the same. Figure 4.7 illustrates that we can perceive the same thing quite differently (i.e. the letter “B” or the number “13”). This shows the influence of context on our information processing.

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In aviation maintenance it is often necessary to consult documents with which the engineer can become very familiar. It is possible that an engineer can scan a document and fail to notice that subtle changes have been made. He sees only what he expects to see (expectation). To illustrate how our eyes can deceive us when quickly scanning a sentence, read quickly the sentence below in Figure 4.8. Expectation can also affect our memory of events. The study outlined above was extended such that subjects were asked, a week later, whether they recalled seeing glass on the road after the collision. (There was no glass). The group, who had been told that they would see a crash, recalled seeing glass; the other group recalled seeing no glass.

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DECISION MAKING Having recognized coherent information from the stimuli reaching our senses, a course of action has to be decided upon. In other words decision making occurs. This may range from deciding to do nothing, to deciding to act immediately in a very specific manner. A fire alarm bell, for instance, may trigger a well-trained sequence of actions without further thought (i.e. evacuate); alternatively, an unfamiliar siren may require further information to be gathered before an appropriate course of action can be initiated. We are not usually fully aware of the processes and information which we use to make a decision. Tools can be used to assist the process of making a decision. For instance, in aircraft maintenance engineering, many documents (e.g. maintenance manuals, fault diagnosis manuals), and procedures are available to supplement the basic decision making skills of the individual. Thus, good decisions are based on knowledge supplemented by written information and procedures, analysis of observed symptoms, performance indications, etc. It can be dangerous to believe that existing knowledge and prior experience will always be sufficient in every situation as will be shown in the section entitled ‘Information Processing Limitations’. Finally, once a decision has been made, an appropriate action can be carried out. Our senses receive of this and its result. This helps to improve knowledge and refine future judgment by learning from experience.

9.4.5 SITUATION AWARENESS Although not shown explicitly in Figure 4.5, the process of attention, perception and judgment should result in awareness of the current situation. Situation awareness has traditionally been used in the context of the flight deck to describe the pilot’s awareness of what is going on around him, e.g. where he is geographically, his orientation in space, what mode the aircraft is in, etc. In the maintenance engineering context, it refers to the:  perception of important elements, e.g. seeing loose bolts or missing parts, hearing information ed verbally  comprehension of their meaning, e.g. why is it like this? Is this how it should be?  projection of their status into the future, e.g. future effects on safety, schedule, airworthiness As with decision making, improves situation awareness by informing us of the accuracy of our mental models and their predictive power. The ability to project system status backward, to determine what events may have led to an observed system state, is also very important in aircraft maintenance engineering, as it allows effective fault finding

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and diagnostic behaviour. Situation awareness for the aircraft maintenance engineer can be summarized as the:  status of the system the engineer is working on  the relationship between the reported defect and the intended rectification  the possible effect of this work on other systems  the effect of this work on that being done by others and the effect of their work on this work

9.4.6 MEMORY Memory is critical to our ability to act consistently and to learn new things. Without memory, we could not capture a ‘stream’ of information reaching our senses, or draw on past experience and apply this knowledge when making decisions. Memory depends on three processes:  registration - the input of information into memory  storage - the retention of information  retrieval - the recovery of stored information It is possible to distinguish between three forms of memory: a) ultra short-term memory (or sensory storage) b) short term memory (often referred to as working memory) c) long term memory Ultra short-term memory has already been described when examining the role of sensory stores. It has a duration of up to 2 seconds (depending on the sense) and is used as a buffer, giving us time to attend to sensory input. Short term memory receives a proportion of the information received into sensory stores, and allows us to store information long enough to use it (hence the idea of ‘working memory’). It can store only a relatively small amount of information at one time, i.e. 5 to 9 (often referred to as 7 ±2) items of information, for a short duration, typically 10 to 20 seconds. As the following example shows, capacity of short term memory can be enhanced by splitting information in to ‘chunks’ (a group of related items).

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For example: A telephone number, e.g. 01222555234, can be stored as 11 discrete digits, in which case it is unlikely to be ed. Alternatively, it can be stored in chunks of related information, e.g. in the UK, 01222 may be stored as one chunk, 555 as another, and 234 as another, using only 3 chunks and therefore, more likely to be ed. In mainland Europe, the same telephone number would probably be stored as 01 22 25 55 23 4, using 6 chunks. The size of the chunk will be determined by the individual’s familiarity with the information (based on prior experience and context), thus in this example, a person from the UK might recognize 01222 as the code for London, but a person from mainland Europe might not. The duration of short term memory can be extended through rehearsal (mental repetition of the information) or encoding the information in some meaningful manner (e.g. associating it with something as in the example above). The capacity of long-term memory appears to be unlimited. It is used to store information that is not currently being used, including:  knowledge of the physical world and objects within it and how these behave  personal experiences  beliefs about people, social norms, values, etc.  motor programmes, problem solving skills and plans for achieving various activities  abilities, such as language comprehension Information in long-term memory can be divided into two types: (i) semantic and (ii) episodic. Semantic memory refers to our store of general, factual knowledge about the world, such as concepts, rules, one’s own language, etc. It is information that is not tied to where and when the knowledge was originally acquired. Episodic memory refers to memory of specific events, such as our past experiences (including people, events and objects). We can usually place these things within a certain context. It is believed that episodic memory is heavily influenced by a person’s expectations of what should have happened, thus two people’s recollection of the same event can differ. MOTOR PROGRAMMES If a task is performed often enough, it may eventually become automatic and the required skills and actions are stored in long term memory. These are known as motor programmes and are ingrained routines that have been established through practice. The use of a motor programme reduces the load on the central decision maker. An often quoted example is that of driving a car: at first, each individual action such as gear changing is demanding, but eventually the separate actions are combined into a motor programme and

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can be performed with little or no awareness. These motor programmes allow us to carry out simultaneous activities, such as having a conversation whilst driving. INFORMATION PROCESSING LIMITATIONS The basic elements of human information processing have now been explored. It is important to appreciate that these elements have limitations. As a consequence, the aircraft engineer, like other skilled professionals, requires such as reference to written material (e.g. manuals).

DECISION MAKING, MEMORY, AND MOTOR PROGRAMMES Attention and perception shortcomings can clearly impinge on decision making. Perceiving something incorrectly may mean that an incorrect decision is made, resulting in an inappropriate action. Figure 4.5 also shows the dependence on memory to make decisions. It was explained earlier that sensory and short-term memory has limited capacity, both in of capacity and duration. It is also important to bear in mind that human memory is fallible, so that information:  may not be stored  may be stored incorrectly  may be difficult to retrieve All these may be referred to as forgetting, which occurs when information is unavailable (not stored in the first place) or inaccessible (cannot be retrieved). Information in short-term memory is particularly susceptible to interference, an example of which would be trying to a part number whilst trying to recall a telephone number. It is generally better to use manuals and temporary aides-memoirs rather than to rely upon memory, even in circumstances where the information to be ed or recalled is relatively simple. For instance, an aircraft maintenance engineer may think that he will a torque setting without writing it down, but between consulting the manual and walking to the aircraft (possibly stopping to talk to someone on the way), he may forget the setting or confuse it (possibly with a different torque setting appropriate to a similar task with which he is more familiar). Additionally, if unsure of the accuracy of memorized information, an aircraft maintenance engineer should seek to check it, even if this means going elsewhere to do so. Noting something down temporarily can avoid the risk of forgetting or confusing information. However, the use of a personal note book to capture such information on a permanent basis can be dangerous, as the information in it may become out-of-date.

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In the B737 double engine oil loss incident, the AAIB report stated: “Once the Controller and fitter had got to T2 and found that this ive material [Task Cards and AMM extracts] was not available in the work pack, they would have had to return to Base Engineering or to have gone over to the Line Maintenance office to get it. It would be, in some measure, understandable for them to have a reluctance to re-cross the exposed apron area on a winter’s night to obtain a description of what they were fairly confident they knew anyway. However, during the course of the night, both of them had occasion to return to the Base Maintenance hangar a number of times before the task had been completed. Either could, therefore, have referred to or even drawn the task descriptive papers before the job was signed off. The question that should be addressed, therefore, is whether there might be any factors other than overconfidence in their memories, bad judgment or idleness which would dispose them to up these opportunities to refresh their memories on the proper and complete procedures.”

9.4.7 CLAUSTROPHOBIA AND PHYSICAL ACCESS Although not peculiar to aircraft maintenance engineering, working in restricted space and at heights is a feature of this trade. Problems associated with physical access are not uncommon. Maintenance engineers and technicians often have to access, and work in, very small spaces (e.g. in fuel tanks), cramped conditions (such as beneath flight instrument s, around rudder pedals), elevated locations (on cherry-pickers or staging), sometimes in uncomfortable climatic or environmental conditions (heat, cold, wind, rain, noise). This can be aggravated by aspects such as poor lighting or having to wear breathing apparatus. There are many circumstances where people may experience various levels of physical or psychological discomfort when in an enclosed or small space, which is generally considered to be quite normal. When this discomfort becomes extreme, it is known as claustrophobia. It is quite possible that susceptibility to claustrophobia is not apparent at the start of employment. It may come about for the first time because of an incident when working within a confined space, e.g. panic if unable to extricate oneself from a fuel tank. If an engineer suffers an attack of claustrophobia, they should make their colleagues and supervisors aware so that if tasks likely to generate claustrophobia cannot be avoided, at least colleagues may be able to assist in extricating the engineer from the confined space quickly, and sympathetically. Engineers should work in a team and assist one another if necessary, making allowances for the fact that people come in all shapes and sizes and that it may be easier for one person to access a space, than another. However, this should not be used as an excuse

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for an engineer who has put on weight, to excuse himself from jobs which he would previously have been able to do with greater ease! Claustrophobia can be defined as abnormal fear of being in an enclosed space.

FEAR OF HEIGHTS Working at significant heights can also be a problem for some aircraft maintenance engineers, especially when doing ‘crown’ inspections (top of fuselage, etc.). Some engineers may be quite at ease in situations like these whereas others may be so uncomfortable that they are far more concerned about the height, and holding on to the access equipment, than they are about the job in hand. In such situations, it is very important that appropriate use is made of harnesses and safety ropes. These will not necessarily remove the fear of heights, but will certainly help to reassure the engineer and allow him to concentrate on the task in hand. The FAA’s http://www.hfskyway.faa.gov website provides practical guidance to access equipment when working at height. Ultimately, if an engineer finds working high up brings on phobic symptoms (such as severe anxiety and panic); they should avoid such situations for safety’s sake. However, as with claustrophobia, from team can be helpful. Managers and supervisors should attempt to make the job as comfortable and secure as reasonably possible (e.g. providing knee pad rests, ensuring that staging does not wobble, providing ventilation in enclosed spaces, etc.) and allow for frequent breaks if practicable. Shortly before the Aloha accident, during maintenance, the inspector needed ropes attached to the rafters of the hangar to prevent falling from the aircraft when it was necessary to inspect rivet lines on top of the fuselage. Although unavoidable, this would not have been conducive to ensuring that the inspection was carried out meticulously (nor was it, as the subsequent accident investigation revealed). The NTSB investigation report stated: “Inspection of the rivets required inspectors to climb on scaffolding and move along the upper fuselage carrying a bright light with them; in the case of an eddy current inspection, the inspectors needed a probe, a meter, and a light. At times, the inspector needed ropes attached to the rafters of the hangar to prevent falling from the airplane when it was necessary to inspect rivet lines on top of the fuselage. Even if the temperatures were comfortable and the lighting was good, the task of examining the area around one rivet after another for signs of minute cracks while standing on scaffolding or on top of the fuselage is very tedious. After examining more and more rivets and finding no cracks, it is natural to begin to expect that cracks will not be found.”

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9.4.8 MOTIVATION Motivated behaviour is goal-directed, purposeful behaviour, and no human behaviour occurs without some kind of motivation underpinning it. In aircraft maintenance, engineers are trained to carry out the tasks within their remit. However, it is largely their motivation which determines what they actually do in any given situation. Thus, “motivation reflects the difference between what a person can do and what he will do”. Motivation is usually considered to be a positive rather than a negative force in that it stimulates one to achieve various things. However just because someone is motivated, this does not mean to say that he is doing the right thing. Many Motivations can be thought of as a basic human drive that arouses, directs and sustains all human behaviour. Generally we say a person is motivated if he is taking action to achieve something. Criminals are highly motivated for instance. Motivation is difficult to measure and predict. We are all motivated by different things, for example, an artist might strive over many months to complete a painting that he may never sell, whereas a businessman may forfeit all family life in pursuit of financial success. With respect to aviation safety, being appropriately motivated is vital. Ideally, aircraft maintenance engineers ought to be motivated to work in a safe and efficient manner. However, many factors may cause conflicting motivations to override this ideal. For instance, the motivation of some financial bonus, or de-motivation of working outdoors in extreme cold weather might lead to less consideration of safety and increase the likelihood of risk taking, corner cutting, violating procedures and so on. Aircraft maintenance engineers should be aware of conflicting motivations that impinge on their actions and attempt to examine their motivations for working in a certain way.

MASLOW’S HIERARCHY OF NEEDS Possibly one of the most well known theories which attempts to describe human motivation is Maslow’s hierarchy of needs. Maslow considered that humans are driven by two different sets of motivational forces:  those that ensure survival by satisfying basic physical and psychological needs  those that help us to realize our full potential in life known as self-actualization needs (fulfilling ambitions, etc.) Figure 4.9 shows the hypothetical hierarchical nature of the needs we are motivated to satisfy. The theory is that the needs lower down the hierarchy are more primitive or basic and must be satisfied before we can be motivated by the higher needs. For instance, you will probably find it harder to concentrate on the information in this document if you are very hungry (as the lower level physiological need to eat predominates over the higher level cognitive need to gain knowledge). There are always exceptions to this, such as the Page No 4-24





mountain climber who risks his life in the name of adventure. The higher up the hierarchy one goes, the more difficult it becomes to achieve the need. High level needs are often longterm goals that have to be accomplished in a series of steps. An aircraft maintenance engineer will fulfill lower level needs by earning money to buy food, pay for a home and a family. They may well be motivated by middle level needs in their work context (e.g. social groups at work, gaining status and recognition). It is noteworthy that for shift workers, tiredness may be a more powerful motivator than a higher order need (such as personal satisfaction to get the job done in time or accurately). An interesting experiment on motivation was carried out in 1924 at the Hawthorne Works of the Western Electric Company in Chicago. Here, the management altered various factors such as rest periods, lighting levels, working hours, etc. and each time they did so, performance improved, even when the apparent improvements were taken away! This suggested that it was not the improvements themselves which were causing the increased production rates, but rather the fact that the staff felt that management were taking notice of them and were concerned for their welfare. This phenomenon is known as the Hawthorne effect.

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DE-MOTIVATION Highly motivated people tend to show the following characteristics:  high performance and results being consistently achieved  the energy, enthusiasm and determination to succeed  unstinting co-operation in overcoming problems  willingness to accept responsibility  willingness to accommodate change People who are de-motivated lack motivation, either intrinsically or through a failure of their management to motivate the staff who works for them. De-motivated people tend to demonstrate the following characteristics:  apathy and indifference to the job, including reduced regard for safety whilst working  a poor record of time keeping and high absenteeism  an exaggeration of the effects/difficulties encountered in problems, disputes and grievances  a lack of co-operation in dealing with problems or difficulties  unjustified resistance to change However, care should be taken when associating these characteristics with lack of motivation, since some could also be signs of stress. There is much debate as to the extent to which financial reward is a motivator. There is a school of thought which suggests that whilst lack of financial reward is a de-motivator, the reverse is not necessarily true. The attraction of the extra pay offered to work a ‘ghoster’1 can be a strong motivator for an individual to ignore the dangers associated with working when tired. The motivating effects of job security and the de-motivating impact of lack of job security is also an area that causes much debate. The ‘hire and fire’ attitude of some companies can, potentially, be a major influence upon safety, with real or perceived pressure upon individuals affecting their performance and actions. It is important that maintenance engineers are motivated by a desire to ensure safety (Maslow’s ‘self esteem/self respect’), rather than by a fear of being punished and losing their job (Maslow’s ‘security’). It is possible that the “can do” culture, which is evident in some areas of the industry, may be generated by the expectancy that if individuals do not ‘deliver’, they will be

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punished (or even dismissed) and, conversely, those who do ‘deliver’ (whether strictly by the book or not, finding ways around lack of time, spares or equipment) are rewarded and promoted. This is not motivation in the true sense but it has its roots in a complex series of pressures and drives and is one of the major influences upon human performance and human error in maintenance engineering. 9.4.9 FITNESS / HEALTH The job of an aircraft maintenance engineer can be physically demanding. In addition, his work may have to be carried out in widely varying physical environments, including cramped spaces, extremes of temperature, etc. There are at present no defined requirements for physical or mental fitness for engineers or maintenance staff. ICAO Annex 11 states: “An applicant shall, before being issued with any licence or rating [for personnel other than flight crew ], meet such requirements in respect of age, knowledge, experience and, where appropriate, medical fitness and skill, as specified for that licence or rating.” In the UK, the ICAO requirements are enforced through the provision of Article 13 (paragraph 7) of the Air Navigation order (ANO). This state: “The holder of an aircraft maintenance engineer’s license shall not exercise the privileges of such a license if he knows or suspects that his physical or mental condition renders him unfit to exercise such privileges.” There are two aspects to fitness and health: the disposition of the engineer prior to taking on employment and the day-to-day well being of the engineer once employed. PRE-EMPLOYMENT DISPOSITION Some employers may require a medical upon commencement of employment. This allows them to judge the fitness and health of an applicant (and this may also satisfy some pension or insurance related need). There is an obvious effect upon an engineer’s ability to perform maintenance or carry out inspections if through poor physical fitness or health he is constrained in some way (such as his freedom of movement, or his sight). In addition, an airworthiness authority, when considering issuing a licence, will consider these factors and may judge the condition to be of such significance that a licence could not be issued. This would not, however, affect the individual’s possibility of obtaining employment in an alternative post within the industry where fitness and health requirements are less stringent.

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DAY-TO-DAY FITNESS AND HEALTH Fitness and health can have a significant affect upon job performance (both physical and cognitive). Day-to-day fitness and health can be reduced through illness (physical or mental) or injury. Responsibility falls upon the individual aircraft maintenance engineer to determine whether he is not well enough to work on a particular day. Alternatively, his colleagues or supervisor may persuade or advise him to absent himself until he feels better. In fact, as the CAA’s Airworthiness Notice No. 47 (AWN47)1 points out; it is a legal requirement for aircraft maintenance engineers to make sure they are fit for work: “Fitness: In most professions there is a duty of care by the individual to assess his or her own fitness to carry out professional duties. This has been a legal requirement for some time for doctors, flight crew and air traffic controllers. Licensed aircraft maintenance engineers are also now required by law to take a similar professional attitude. Cases of subtle physical or mental illness may not always be apparent to the individual but as engineers often work as a member of a team any substandard performance or unusual behaviour should be quickly noticed by colleagues or supervisors who should notify management so that appropriate and counselling action can be taken.” Many conditions can impact on the health and fitness of an engineer and there is not space here to offer a complete list. However, such a list would include:  Minor physical illness (such as colds, ‘flu, etc.)  More major physical illness (such as HIV, malaria, etc.)  Mental illness (such as depression, etc.)  Minor injury (such as a sprained wrist, etc.)  Major injury (such as a broken arm, etc.)  Ongoing deterioration in physical condition, possibly associated with the ageing process (such as hearing loss, visual defects, obesity, heart problems, etc.  Affects of toxins and other foreign substances (such as carbon monoxide poisoning, alcohol, illicit drugs, etc.) ‘Unfit for work’ is a complex issue dependent upon the nature of the illness or condition, its effect upon the individual, the type of work to be done, environmental conditions, etc. Instead, it is important that the engineer is aware that his performance, and consequently the safety of aircraft he works on, might be affected adversely by illness or lack of fitness.

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An engineer may consider that he is letting down his colleagues by not going to work through illness, especially if there are ongoing manpower shortages. However, he should remind himself that, in theory, management should generally allow for contingency for illness. Hence the burden should not be placed upon an individual to turn up to work when unfit if no such contingency is available. Also, if the individual has a contagious illness (e.g. ‘flu), he may this on to his colleagues if he does not absent himself from work and worsen the manpower problem in the long run. There can be a particular problem with some contract staff due to loss of earnings or even loss of contract if absent from work due to illness. They may be tempted to disguise their illness, or may not wish to it to themselves or others that they are ill. This is of course irresponsible, as the illness may well adversely affect the contractor’s standard of work. POSITIVE MEASURES Aircraft maintenance engineers can take common sense steps to maintain their fitness and health. These include:  Eating regular meals and a well-balanced diet  Taking regular exercise (exercise sufficient to double the resting pulse rate for 20 minutes, three times a week is often recommended)  Stopping smoking  Sensible alcohol intake (for men, this is no more than 3 - 4 units a day or 28 per week, where a unit is equivalent to half a pint of beer or a glass of wine or spirit) Finally, day-to-day health and fitness can be influenced by the use of medication, alcohol and illicit drugs. 9.4.10 STRESS STRESS: DOMESTIC AND WORK RELATED Stress is an inescapable part of life for all of us. From a human viewpoint, stress results from the imposition of any demand or set of demands which require us to react, adapt or behave in a particular manner in order to cope with or satisfy them. Up to a point, such demands are stimulating and useful, but if the demands are beyond our personal capacity to deal with them, the resulting stress is a problem. Stress can be defined as any force, that when applied to a system, causes some significant modification of its form, where forces can be physical, psychological or due to social pressures.

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CAUSES AND SYMPTOMS Stress is usually something experienced due to the presence of some form of stressor, which might be a one-off stimulus (such as a challenging problem or a punch on the nose), or an on-going factor (such as an extremely hot hangar or an acrimonious divorce). From these, we get acute stress (typically intense but of short duration) and chronic stress (frequent recurrence or of long duration) respectively. Different stressors affect different people to varying extents. Stressors may be:  Physical - such as heat, cold, noise, vibration, presence of something damaging to health (e.g. carbon monoxide)  Psychological - such as emotional upset (e.g. due to bereavements, domestic problems, etc.), worries about real or imagined problems (e.g. due to financial problems, ill health, etc.)  Reactive - such as events occurring in everyday life (e.g. working under time pressure, encountering unexpected situations, etc.) “A stress problem can manifest itself by signs of irritability, forgetfulness, and sickness absence, mistakes, or alcohol or drug abuse. Management has a duty to identify individuals who may be suffering from stress and to minimize workplace stresses. Individual cases can be helped by sympathetic and skilful counseling which allows a return to effective work and licensed duties.” In brief, the possible signs of stress can include:  Physiological symptoms - such as sweating, dryness of the mouth, etc.  Health effects - such as nausea, headaches, sleep problems, diarrhoea, ulcers, etc.  Behavioural symptoms - such as restlessness, shaking, nervous laughter, taking longer over tasks, changes to appetite, excessive drinking, etc.  Cognitive effects - such as poor concentration, indecision, forgetfulness, etc.  Subjective effects - such as anxiety, irritability, depression, moodiness, aggression, etc. DOMESTIC STRESS When aircraft maintenance engineers go to work, they cannot leave stresses associated with home behind. Pre-occupation with a source of domestic stress can play on one’s mind during the working day, distracting from the working task. Inability to concentrate fully may impact on the engineer’s task performance and ability to pay due attention to safety. Domestic stress typically results from major life changes at home, such as marriage, birth of a child, a son or daughter leaving home, bereavement of a close family member or

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friend, marital problems, or divorce. It should be noted that individuals respond to stressful situations in very different ways. Generally speaking though, people tend to regard situations with negative consequences as being more stressful than when the outcome of the stress will be positive (e.g. the difference between being made redundant from work and being present at the birth of a son or daughter). WORK RELATED STRESS Aircraft maintenance engineers can experience stress for two reasons at work: because of the task or job they are undertaking at that moment, or because of the general organizational environment. Stress can be felt when carrying out certain tasks that are particularly challenging or difficult. This stress can be increased by lack of guidance in this situation, or time pressures to complete the task or job (covered later in this chapter). This type of stress can be reduced by careful management, good training, etc. Within the organization, the social and managerial aspects of work can be stressful. Earlier we discussed the impact on the individual of peer pressure, organizational culture and management, all of which can be stressors. In the commercial world that aircraft maintenance engineers work in, shift patterns, lack of control over own workload, company reorganization and job uncertainty can also be sources of stress.

STRESS MANAGEMENT Once we become aware of stress, we generally respond to it by using one of two strategies: defence or coping. Coping strategies involve dealing with the source of the stress rather than just the symptoms (e.g. delegating workload, prioritizing tasks, sorting out the problem, etc.). Unfortunately, it is not always possible to deal with the problem if this is outside the control of the individual (such as during an emergency), but there are wellpublished techniques for helping individuals to cope with stress2. Good stress management techniques include:  Relaxation techniques  Careful regulation of sleep and diet  A regime of regular physical exercise  Counseling - ranging from talking to a ive friend or colleague to seeking professional advice There is no magic formula to cure stress and anxiety, merely common sense and practical advice.

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9.4.11 WORKLOAD MANAGEMENT In a commercial environment, it is seldom possible to make large amendments to maintenance schedules, nor eliminate time pressures. The essence of workload management in aircraft maintenance should include:  ensuring that staff have the skills needed to do the tasks they have been asked to do and the proficiency and experience to do the tasks within the timescales they have been asked to work within  making sure that staff have the tools and spares they need to do the tasks  allocating tasks to teams or individual engineers that are accomplishable (without cutting corners) in the time available  providing human factors training to those responsible for planning so that the performance and limitations of their staff are taken into  encouraging individual engineers, supervisors and managers to recognize when an overload situation is building up If an overload situation is developing, methods to help relieve this include:  seeking a simpler method of carrying out the work (that is just as effective and still legitimate)  delegating certain activities to others to avoid an individual engineer becoming overloaded  securing further time in order to carry out the work safely  postponing, delaying tasks/deadlines and refusing additional work Thus, although workload varies in aircraft maintenance engineering, the workload of engineers can be moderated. Much of this can be done by careful forward planning of tasks, manpower, spares, tools and training of staff.

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9.4.12 FATIGUE Fatigue can be either physiological or subjective. Physiological fatigue reflects the body’s need for replenishment and restoration. It is tied in with factors such as recent physical activity, current health, consumption of alcohol, and with circadian rhythms. It can only be satisfied by rest and eventually, a period of sleep. Subjective fatigue is an individual’s perception of how sleepy they feel. This is not only affected by when they last slept and how good the sleep was but other factors, such as degree of motivation. Fatigue is typically caused by delayed sleep, sleep loss, de-synchronisation of normal circadian rhythms and concentrated periods of physical or mental stress or exertion. In the workplace, working long hours, working during normal sleep hours and working on rotating shift schedules all produce fatigue to some extent. Although there are many contributory factors, it is noteworthy that a number of major incidents and accidents involving human error have either occurred or were initiated in the pre-dawn hours, when body temperature and performance capability are both at their lowest. These include Three Mile Island, Chernobyl, and Bhopal, as well as the BAC111, A320, and B737 incidents summarized earlier. Symptoms of fatigue (in no particular order) may include:  diminished perception (vision, hearing, etc.) and a general lack of awareness  diminished motor skills and slow reactions  problems with short-term memory  channeled concentration - fixation on a single possibly unimportant issue, to the neglect of others and failing to maintain an overview  being easily distracted by unimportant matters  poor judgment and decision making leading to increased mistakes  abnormal moods - erratic changes in mood, depressed, periodically elated and energetic  diminished standards of own work “Tiredness and fatigue can adversely affect performance. Excessive hours of duty and shift working, particularly with multiple shift periods or additional overtime, can lead to problems. Individuals should be fully aware of the dangers of impaired performance due to these factors and of their personal responsibilities.”

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9.4.13 ALCOHOL, MEDICATION AND DRUGS It should come as no surprise to the aircraft maintenance engineer that his performance will be affected by alcohol, medication or illicit drugs. Under both UK and JAA legislation it is an offence for safety critical personnel to carry out their duties whilst under the influence of alcohol or drugs. Article 13 (paragraph 8) of the UK ANO, states: “The holder of an aircraft maintenance engineer’s license shall not, when exercising the privileges of such a license, be under the influence of drink or a drug to such an extent as to impair his capacity to exercise such privileges.” The current law which does not prescribe a blood/alcohol limit is soon to change. There will be new legislation permitting police to test for drink or drugs where there is reasonable cause, and the introduction of a blood/alcohol limit of 20 milligrams of alcohol per 100 millilitres of blood for anyone performing a safety critical role in UK civil aviation (which includes aircraft maintenance engineers). It is always sensible to monitor ones performance, especially when working additional hours. Performance decrements can be gradual, and first signs of chronic fatigue may be moodiness, headaches or finding that familiar tasks (such as programming the video recorder) seem more complicated than usual.

ALCOHOL Alcohol acts as a depressant on the central nervous system, dulling the senses and increasing mental and physical reaction times. It is known that even a small amount of alcohol leads to a decline in an individual’s performance and may cause his judgment (i.e. ability to gauge his performance) to be hindered. Alcohol is removed from the blood at a fixed rate and this cannot be speeded up in any way (e.g. by drinking strong coffee). In fact, sleeping after drinking alcohol can slow down the removal process, as the body’s metabolic systems are slower. “Alcohol has similar effects to tranquillizers and sleeping tablets and may remain circulating in the blood for a considerable time, especially if taken with food. It may be borne in mind that a person may not be fit to go on duty even 8 hours after drinking large amounts of alcohol. Individuals should therefore anticipate such effects upon their next duty period. Special note should be taken of the fact that combinations of alcohol and sleeping tablets, or anti-histamines, can form a highly dangerous and even lethal combination.” The affects of alcohol can be made considerably worse if the individual is fatigued, ill or using medication.

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MEDICATION Any medication, no matter how common, can possibly have direct effects or side effects that may impair an engineer’s performance in the workplace. There is a risk that these effects can be amplified if an individual has a particular sensitivity to the medication or one of its ingredients. Hence, an aircraft maintenance engineer should be particularly careful when taking a medicine for the first time, and should ask his doctor whether any prescribed drug will affect his work performance. It is also wise with any medication to take the first dose at least 24 hours before any duty to ensure that it does not have any adverse effects. Medication can be regarded as any over-the-counter or prescribed drug used for therapeutic purposes. Various publications and especially AWN47 give advice relevant to the aircraft maintenance engineer on some of the more common medications. This information is summarised below, however the engineer must use this with caution and should seek further clarification from a pharmacist, doctor or their company occupational health advisor if at all unsure of the impact on work performance.  Analgesics are used for pain relief and to counter the symptoms of colds and ‘flu. In the UK, paracetamol, aspirin and ibuprofen are the most common, and are generally considered safe if used as directed. They can be taken alone but are often used as an ingredient of a ‘cold relief’ medicine. It is always worth bearing in mind that the pain or discomfort that you are attempting to treat with an analgesic (e.g. headache, sore throat, etc.) may be the symptom of some underlying illness that needs proper medical attention.  Antibiotics (such as Penicillin and the various mycins and cyclines) may have short term or delayed effects which affect work performance. Their use indicates that a fairly severe infection may well be present and apart from the effects of these substances themselves, the side-effects of the infection will almost always render an individual unfit for work.  Anti-histamines are used widely in ‘cold cures’ and in the treatment of allergies (e.g. hayfever). Most of this group of medicines tend to make the feel drowsy, meaning that the use of medicines containing anti-histamines is likely to be unacceptable when working as an aircraft maintenance engineer.  Cough suppressants are generally safe in normal use, but if an over-the- counter product contains anti-histamine, decongestant, etc., the engineer should exercise caution about its use when working.  Decongestants (i.e. treatments for nasal congestion) may contain chemicals such as pseudo-ephedrine hydrochloride (e.g. ‘Sudafed’) and phenylphrine. Sideeffects reported, are anxiety, tremor, rapid pulse and headache. AWN47 forbids Page No 4-35





the use of medications containing this ingredient to aircraft maintenance engineers when working, as the effects compromise skilled performance.  ‘Pep’ pills are used to maintain wakefulness. They often contain caffeine, dexedrine or benzedrine. Their use is often habit forming. Over-dosage may cause headaches, dizziness and mental disturbances. AWN47 states that “the use of ‘pep’ pills whilst working cannot be permitted. If coffee is insufficient, you are not fit for work.”  Sleeping tablets (often anti-histamine based) tend to slow reaction times and generally dull the senses. The duration of effect is variable from person to person. Individuals should obtain expert medical advice before taking them.  Melatonin (a natural hormone) deserves a special mention. Although not available without a prescription in the UK, it is classed as a food supplement in the USA (and is readily available in health food shops). It has been claimed to be effective as a sleep aid, and to help promote the resynchronisation of disturbed circadian rhythms. Its effectiveness and safety are still yet to be proven and current best advice is to avoid this product. DRUGS llicit drugs such as ecstasy, cocaine and heroin all affect the central nervous system and impair mental function. They are known to have significant effects upon performance and have no place within the aviation maintenance environment. Of course, their possession and use are also illegal in most of the countries. Smoking cannabis can subtly impair performance for up to 24 hours. In particular, it affects the ability to concentrate, retain information and make reasoned judgements, especially on difficult tasks. If the aircraft maintenance engineer has any doubts about the suitability of working whilst taking medication, he must seek appropriate professional advice. 9.4.14 PHYSICAL WORK PLANNING Blindly starting a task without planning how best to do it is almost certainly the best way to invite problems. Before commencing a task, an individual engineer, engineering team or planner should ask themselves a number of questions. These may include:  Do I/we know exactly what the task is that has to be done?  Are the resources available to do it effectively (safely, accurately and within the time permitted)? Where resources include:

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 Personnel  equipment/spares  documentation, information and guidance  facilities such as hangar space, lighting, etc.  Do I/we have the skills and proficiency necessary to complete the task? Information about specific tasks should be detailed on job cards or task sheets. These will indicate the task (e.g. checks or inspection, repair, replacement, overhaul) and often further details to aid the engineer (such as maintenance manual references, part numbers, etc.). It is generally the shift supervisor’s job to ensure that the resources are available for his staff to carry out their tasks. As noted earlier (‘Time Pressure and Deadlines’), it is likely that, within a shift or a team, various sub-tasks are allocated to individuals by the supervisor. Alternatively, he may encourage a team to take ownership of the tasks that need to be completed, giving them the discretion to manage a package of work (as noted earlier (‘Team Working’). Exactly ‘who does what’ is likely to be based on factors such as individuals’ specialization (i.e. A&C or avionics) and their experience with the task. Although management have a responsibility to ensure that their engineers have suitable training, at the end of the day, it is up to the individual engineer to decide whether he has the necessary skills and has the proficiency and experience to do what he has been asked to do. He should not be afraid to voice any misgivings, although it is recognized that peer and management pressure may make this difficult. If the engineer is in any doubt what needs to be done, written guidance material is the best resource. Colleagues may unintentionally give incorrect or imprecise direction (the exception to this is discussing problems that arise that are not covered in the guidance material). PHYSICAL TASKS Aircraft maintenance engineering is a relatively active occupation. Regardless of the job being done, most tasks tend to have elements of fine motor control, requiring precision, as well as activities requiring strength and gross manipulation. From a biomechanical perspective, the human body is a series of physical links (bones) connected at certain points (ts) that allow various movements. Muscles provide the motive force for all movements, both fine and gross. This is known as the musculoskeletal system. The force that can be applied in any given posture is dependent on the strength available from muscles and the mechanical advantage provided by the relative positions of the load, muscle connections, and ts. It is important that maintenance tasks on aircraft are within the physical limitations of aircraft maintenance engineers. Boeing use a computerised tool1, based on human performance data (body sizes, strengths, leverages, pivots, etc.), to ensure that modern

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aircraft are designed such that the majority of maintenance engineers will be able to access aircraft equipment, apply the necessary strength to loosen or tighten objects, etc. (i.e. designed for ease of maintainability). Clearly we are all different in of physical stature and strength and as a consequence, our physical limitations vary. Attempting to lift a heavy object which is beyond our physical capabilities is likely to lead to injury. The use of tools generally make tasks easier, and in some situations, may make a task achievable that was hitherto outside our physical powers (e.g. lifting an aircraft with the aid of a hoist). As noted earlier (‘Fatigue’), physical work over a period of time will result in fatigue. This is normally not a problem if there is adequate rest and recovery time between work periods. It can, however, become a problem if the body is not allowed to recover, possibly leading to illness or injuries. Hence, engineers should try to take their allocated breaks. As discussed at some length earlier (‘Day-to-Day Fitness and Health’), it is very important that engineers should try to ensure that their physical fitness is good enough for the type of tasks which they normally do. As an engineer gets older, the musculoskeletal system stiffens and muscles become weaker. Injuries become more likely and take longer to heal. Staying in shape will minimize the effects of ageing, but they still occur. Missing a break in an effort to get a job done within a certain time frame can be counterproductive, as fatigue diminishes motor skills, perception, awareness and standards. As a consequence, work may slow and mistakes may occur that need to be rectified. 9.4.15 REPETITIVE TASKS / COMPLACENCY Repetitive tasks can be tedious and reduce arousal (i.e. be boring). Most of the human factors research associated with repetitive tasks has been carried out in manufacturing environments where workers carry out the same action many times a minute. This does not generally apply to maintenance engineering. Some engineers may specialize in a certain aspect of maintenance, such as engines. As a result, they may possibly carry out the same or similar tasks several times a day. The main danger with repetitive tasks is that engineers may become so practiced at such tasks that they may cease to consult the maintenance manual, or to use job cards. Thus, if something about a task is changed, the engineer may not be aware of the change. Complacency is also a danger, whereby an engineer may skip steps or fail to give due attention to steps in a procedure, especially if it is to check something which is rarely found to be wrong, damaged or out of tolerance. This applies particularly to visual inspection, which is covered in greater detail in the next section. Making assumptions along the lines of ‘Oh I’ve done that job dozens of times!’ can occur even if a task has not been undertaken for some time. It is always advisable to be wary of changes to procedures or parts, ing that ‘familiarity breeds contempt’.

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Repetitive tasks in aircraft maintenance engineering typically refer to tasks that are performed several times during a shift, or a number of times during a short time period, e.g. in the course of a week. An example of this would be the checking life jackets on an aircraft during daily inspections. In the Aloha accident report, the NTSB raised the problem of repetitive tasks: “The concern was expressed about what kinds of characteristics are appropriate to consider when selecting persons to perform an obviously tedious, repetitive task such as a protracted NDI inspection. Inspectors normally come up through the seniority ranks. If they have the desire, knowledge and skills, they bid on the position and are selected for the inspector job on that basis. However, to ask a technically knowledgeable person to perform an obviously tedious and exceedingly boring task, rather than to have him supervise the quality of the task, may not be an appropriate use of personnel…”

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MODULE 9

HUMAN FACTORS

SUB MODULE 9.5

ENVIRONMENT

Page No i





CONTENTS 9.5 ENVIRONMENT ...............................................................................

5-1

9.5.1 Peer Pressure ...........................................................................

5-1

Experiments in Conformity ...............................................................

5-1

Countering Peer Pressure and Conformity .......................................

5-3

9.5.2 Stressors .......................................................................................

5-3

9.5.3 Time Pressure and deadlines .......................................................

5-4

The Effects of Time Pressure and Deadlines ....................................

5-4

Managing Time Pressure and Deadlines ..........................................

5-4

9.5.4 Workload......................................................................................

5-5

Arousal ..............................................................................................

5-6

Factors Determining Workload.........................................................

5-7

9.5.5 Shift Work ................................................................................

5-9

Sleep, Fatigue, Shift Work and the Aircraft Maintenance Engineer.

5-10

9.5.6 Noise and fumes ..........................................................................

5-11

Noise .................................................................................................

5-11

Fumes ................................................................................................

5-12

9.5.7 Illumination ..................................................................................

5-13

9.5.8 Climate and Temperature ............................................................

5-15

9.5.9 Motion and Vibration...................................................................

5-16

9.5.10 Complex systems .......................................................................

5-17

9.5.11 Hazards in the Workplace ..........................................................

5-19

Potential Hazards in Aircraft Maintenance Engineering ..................

5-19

Relevant Legislation and the Maintenance Organization’s Responsibilities5-19 Engineer’s Individual Responsibilities ...............................................

5-20

Dealing with Emergencies.................................................................

5-21

The basic actions in an emergency are to: .......................................

5-22

9.5.12 Lack of manpower......................................................................

5-23

9.5.13 Distractions and interruptions ...................................................

5-23

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9.5 ENVIRONMENT 9.5.1 PEER PRESSURE In the working environment of aircraft maintenance, there are many pressures brought to bear on the individual engineer. We have already discussed the influence of the organization, of responsibility and motivational drives. In addition to these, there is the possibility that the aircraft maintenance engineer will receive pressure at work from those that work with him. This is known as peer pressure. For example, an individual engineer may feel that there is pressure to cut corners in order to get an aircraft out by a certain time, in the belief that this is what his colleagues would do under similar circumstances. There may be no actual pressure from management to cut corners, but subtle pressure from peers, e.g. taking the form of comments such as “You don’t want to bother checking the manual for that. You do it like this…” would constitute peer pressure. Peer pressure thus falls within the area of conformity. Conformity is the tendency to allow one’s opinions, attitudes, actions and even perceptions to be affected by prevailing opinions, attitudes, actions and perceptions.

EXPERIMENTS IN CONFORMITY Asch carried out several experiments investigating the nature of conformity, in which he asked people to judge which of lines A, B & C was the same length as line X. (see Figure 5.1). He asked this question under different conditions:  where the individual was asked to make the judgment on his own  where the individual carried out the task after a group of 7-9 confederates of Asch and all judged that line A was the correct choice. Of course, the real participant did not know the others were “stooges” In the first condition, very few mistakes were made (as would be expected of such a simple task with an obvious answer). In the latter condition, on average, participants gave wrong answers on one third of the trials by agreeing with the confederate majority. Clearly, participants yielded to group pressure and agreed with the incorrect ‘group’ finding (however, it is worth mentioning that there were considerable Peer pressure is the actual or perceived pressure which an individual may feel, to conform to what he believes that his peers or colleagues expect.

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Further research indicated that conformity does not occur with only one confederate (as then it is a case of ‘my word against yours’). However, it is necessary to have only three confederates to one real participant to attain the results that Asch found with 7- 9 confederates. The degree, to which an individual’s view is likely to be affected by conformity or peer pressure, depends on many factors, including:  culture (people from country x tend to conform more than those from country y)  gender (men tend to conform less than women)  self-esteem (a person with low self-esteem is likely to conform more)  familiarity of the individual with the subject matter (a person is more likely to conform to the majority view if he feels that he knows less about the subject matter than they do)  the expertise of the group (if the individual respects the group or perceives them to be very knowledgeable he will be more likely to conform to their views)  the relationship between the individual and group (conformity increases if the individual knows the other of the group, i.e. it is a group of peers)

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COUNTERING PEER PRESSURE AND CONFORMITY The influence of peer pressure and conformity on an individual’s views can be reduced considerably if the individual airs their views publicly from the outset. However, this can be very difficult: after Asch’s experiments, when asked, many participants said they agreed with the majority as they did not want to appear different or to look foolish. Conformity is closely linked with ‘culture’ (described in the next section). It is highly relevant in the aircraft maintenance environment where it can work for or against a safety culture, depending on the attitudes of the existing staff and their influence over newcomers. In other words, it is important for an organization to engender a positive approach to safety throughout their workforce, so that peer pressure and conformity perpetuates this. In this instance, peer pressure is clearly a good thing. Too often, however, it works in reverse, with safety standards gradually deteriorating as shift develop practices which might appear to them to be more efficient, but which erode safety. These place pressure, albeit possibly unwittingly, upon new engineers ing the shift, to do likewise. 9.5.2 STRESSORS Stress' is another small word for a wide range of complex effects. The various types of stressors that are likely to be encountered in maintenance 'work and could have an adverse effect upon performance are summarized below:  Physical stressors - Heat, humidity, confined spaces, noise, vibration and the like  Socially stressors action and so on

Anxiety, group pressures, incentive schemes, disciplinary

 Drugs - Alcohol, nicotine, medication and so on  The pace of Work - Boredom, fatigue, interruptions and time pressures  Personal-factors - Domestic worries, aches and pains, colds and generally feeling below par Stresses resulting from significant life events such as divorce, financial worries and the like can reduce general well-being and increase the susceptibility to some illnesses. The effects of these troubles can spill over into the workplace. People who are experiencing such events may be distracted by intrusive thoughts, particularly when workload is low. In addition, people can take more risks when they are tinder emotional stress brought on by life events such as marriage problems or financial problems. For example, it has been found that people who are facing high levels of life stress are less likey to wear a seat belt when driving.

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9.5.3 TIME PRESSURE AND DEADLINES There is probably no industry in the commercial environment that does not impose some form of deadline, and consequently time pressure, on its employees. Aircraft maintenance is no exception. It was highlighted in the previous section that one of the potential stressors in maintenance is time pressure. This might be actualpressure where clearly specified deadlines are imposed by an external source (e.g. management or supervisors) and ed on to engineers, or perceivedwhere engineers feel that there are time pressures when carrying out tasks, even when no definitive deadlines have been set in stone. In addition, time pressure may be self-imposed, in which case engineers set themselves deadlines to complete work (e.g. completing a task before a break or before the end of a shift). Management has contractual pressures associated with ensuring an aircraft is released to service within the time frame specified by their customers. Striving for higher aircraft utilization means that more maintenance must be accomplished in fewer hours, with these hours frequently being at night. Failure to do so can impact on flight punctuality and enger satisfaction. Thus, aircraft maintenance engineers have two driving forces: the deadlines handed down to them and their responsibilities to carry out a safe job. The potential conflict between these two driving pressures can cause problems.

THE EFFECTS OF TIME PRESSURE AND DEADLINES As with stress, it is generally thought that some time pressure is stimulating and may actually improve task performance. However, it is almost certainly true that excessive time pressure (actual or perceived, external or self-imposed), is likely to mean that due care and attention when carrying out tasks diminishes and more errors will be made. Ultimately, these errors can lead to aircraft incidents and accidents. It is possible that perceived time pressure would appear to have been a contributory factor in the BAC 1-11 accident described in Chapter 1. Although the aircraft was not required the following morning for operational use, it was booked for a wash. The wash team had been booked the previous week and an aircraft had not been ready. This would have happened again, due to short-staffing, so the Shift Manager decided to carry out the windscreen replacement task himself so that the aircraft would be ready in time.

MANAGING TIME PRESSURE AND DEADLINES One potential method of managing time pressures exerted on engineers is through regulation. For example, FAA research has highlighted the need to insulate aircraft

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maintenance engineers from commercial pressures. They consider this would help to ensure that airworthiness issues will always take precedence over commercial and time pressures. Time pressures can make ‘corner-cutting’ a cultural norm in an organization. Sometimes, only an incident or accident reveals such norms (the extract from the Aloha accident above exemplifies this). Those responsible for setting deadlines and allocating tasks should consider:  Prioritizing various pieces of work that need to be done  The actual time available to carry out work (considering breaks, shift handovers etc.)  The personnel available throughout the whole job (allowing a contingency for illness)  The most appropriate utilization of staff (considering an engineer’s specialization, and strengths and limitations)  Availability of parts and spares An extract from the NTSB report on the Aloha accident refers to time pressure as a possible contributory factor in the accident: “The majority of Aloha's maintenance was normally conducted only during the night. It was considered important that the airplanes be available again for the next day's flying schedule. Such aircraft utilization tends to drive the scheduling, and indeed, the completion of required maintenance work. Mechanics and inspectors are forced to perform under time pressure. Further, the intense effort to keep the airplanes flying may have been so strong that the maintenance personnel were reluctant to keep airplanes in the hangar any longer than absolutely necessary.” It is important that engineering staff at all levels are not afraid to voice concerns over inappropriate deadlines, and if necessary, cite the need to do a safe job to this. As highlighted earlier, within aircraft maintenance, responsibility should be spread across all those who play a part. Thus, the aircraft maintenance engineer should not feel that the ‘buck stops here’. 9.5.4 WORKLOAD The preceding sections on stress and time pressure have both indicated that a certain amount of stimulation is beneficial to an aircraft maintenance engineer, but that too much stimulation can lead to stress or over-commitment in of time. It is noteworthy that too little stimulation can also be a problem.

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Before going on to discuss workload, it is important to consider this optimum level of stimulation or arousal.

AROUSAL Arousal in its most general sense refers to readiness of a person for performing work. To achieve an optimum level of task performance, it is necessary to have a certain level of stimulation or arousal. This level of stimulation or arousal varies from person to person. There are people who are overloaded by having to do more than one task at a time; on the other hand there are people who appear to thrive on stress, being happy to take on more and more work or challenges. Figure 16 shows the general relationship between arousal and task performance. At low levels of arousal, our attention mechanisms will not be particularly active and our performance capability will be low (complacency and boredom can result). At the other end of the curve, performance deteriorates when arousal becomes too high. To a certain extent, this is because we are forced to shed tasks and focus on key information only (called narrowing of attention). Best task performance occurs somewhere in the middle. In the work place, arousal is mainly influenced by stimulation due to work tasks. However, surrounding environmental factors such as noise may also influence the level of arousal.

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FACTORS DETERMINING WORKLOAD An individual aircraft maintenance engineer can usually identify what work he has to do quite easily. It is more difficult to assess how that work translates into workload. The degree of stimulation exerted on an individual caused by a task is generally referred to as workload, and can be separated into physical workload and mental workload. As noted in the section on information processing earlier, humans have limited mental capacity to deal with information. We are also limited physically, in of visual acuity, strength, dexterity and so on. Thus, workload reflects the degree to which the demands of the work we have to do eats into our mental and physical capacities. Workload is subjective (i.e. experienced differently by different people) and is affected by:  The nature of the task, such as the  physical demands it requires (e.g. strength required, etc.)  mental demands it requires (e.g. complexity of decisions to be made, etc.).  The circumstances under which the task is performed, such as the  standard of performance required (i.e. degree of accuracy)  time available to accomplish the task (and thus the speed at which the task must be carried out)  requirement to carry out the task at the same time as doing something else  perceived control of the task (i.e. is it imposed by others or under your control, etc.)  environmental factors existing at time (e.g. extremes of temperature, etc.)  The person and his state, such as his:  skills (both physical and mental)  his experience (particularly familiarity with the task in question)  his current health and fitness levels  his emotional state (e.g. stress level, mood, etc.)

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As the workload of the engineer may vary, he may experience periods of overload and under-load. This is a particular feature of some areas of the industry such as line maintenance. OVERLOAD Overload occurs at very high levels of workload (when the engineer becomes over aroused). As highlighted previously, performance deteriorates when arousal becomes too high and we are forced to shed tasks and focus on key information. Error rates may also increase. Overload can occur for a wide range of reasons based on the factors highlighted above. It may happen suddenly (e.g. if asked to one further piece of information whilst already trying to a large amount of data), or gradually. Although EASA part 145.A.30 (d) states that: “The organization shall have a maintenance man-hour plan showing that the organization has sufficient staff to plan, perform, supervise, inspect and quality monitor the organization in accordance with the approval. In addition the organization shall have a procedure to reassess work intended to be carried out when actual staff availability is less than the planned staffing level for any particular work shift or period.” this does not prevent individuals from becoming overloaded. As noted earlier in this section, it can be difficult to determine how work translates into workload, both for the individual concerned, and for those allocating tasks. UNDER-LOAD Under load occurs at low levels of workload (when the engineer becomes under aroused). It can be just as problematic to an engineer as overload, as it too causes deterioration in performance and an increase in errors, such as missed information. Under load can result from a task an engineer finds boring, very easy, or indeed a lack of tasks. The nature of the aircraft maintenance industry means that available work fluctuates, depending on time of day, maintenance schedules, and so forth. Hence, unless stimulating ‘housekeeping’ tasks can be found, under load can be difficult to avoid at times.

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9.5.5 SHIFT WORK Most aircraft movements occur between 6 a.m. and 10 p.m. to fit in with the requirements of engers. Aircraft maintenance engineers are required whenever aircraft are on the ground, such as during turn around. However, this scheduling means that aircraft are often available for more significant maintenance during the night. Thus, aircraft maintenance engineering is clearly a 24 hour business and it is inevitable that, to fulfill commercial obligations, aircraft maintenance engineers usually work shifts. Some engineers permanently work the same shift, but the majority cycle through different shifts. These typically comprise an ‘early shift’, a ‘late shift’ and a ‘night shift’, or a ‘day shift’ and a ‘night shift’ depending on the maintenance organization. ADVANTAGES AND DISADVANTAGES OF SHIFT WORK There are pros and cons to working shifts. Some people welcome the variety of working different times associated with regular shift work patterns. Advantages may include more days off and avoiding peak traffic times when traveling to work. The disadvantages of shift working are mainly associated with:  working ‘unsociable hours’, meaning that time available with friends, family, etc. will be disrupted  working when human performance is known to be poorer (i.e. between 4 a.m. and 6 a.m.)  problems associated with general de-synchronization and disturbance of the body’s various rhythms (principally sleeping patterns) WORKING AT NIGHT Shift work means that engineers will usually have to work at night, either permanently or as part of a rolling shift pattern. As discussed earlier in this chapter, this introduces the inherent possibility of increased human errors. Working nights can also lead to problems sleeping during the day, due to the interference of daylight and environmental noise. Blackout curtains and use of ear plugs can help, as well as avoidance of caffeine before sleep. ROLLING SHIFT PATTERNS When an engineer works rolling shifts and changes from one shift to another (e.g. ‘day shift’ to ‘night shift’), the body's internal clock is not immediately reset. It continues on its old wake-sleep cycle for several days, even though it is no longer possible for the person to sleep when the body thinks it is appropriate, and is only gradually resynchronised. However, by this time, the engineer may have moved onto the next shift. Generally, it is now accepted Page No 5-10





that shift rotation should be to later shifts (i.e. early shift _ late shift _ night shift or day shift _ night shift) instead of rotation towards earlier shifts (night shift _ late shift _ early shift). CONTINUITY OF TASKS AND SHIFT HANDOVERS Many maintenance tasks often span more than one shift, requiring tasks to be ed from one shift to the next. The outgoing personnel are at the end of anything up to a twelve hour shift and are consequently tired and eager to go home. Therefore, shift handover is potentially an area where human errors can occur. Whilst longer shifts may result in greater fatigue, the disadvantages may be offset by the fact that fewer shift changeovers are required (i.e. only 2 handovers with 2 twelve hour shifts, as opposed to 3 handovers with 3 eight hour shifts).

SLEEP, FATIGUE, SHIFT WORK AND THE AIRCRAFT MAINTENANCE ENGINEER Most individuals need approximately 8 hours sleep in a 24 hour period, although this varies between individuals, some needing more and some happy with less than this to be fully refreshed. They can usually perform adequately with less that this for a few days, building up a temporary sleep ‘deficit’. However, any sleep deficit will need to be made up, otherwise performance will start to suffer. As previously noted, fatigue is best tackled by ensuring adequate rest and good quality sleep are obtained. The use of blackout curtains if having to sleep during daylight has already been mentioned. It is also best not to eat a large meal shortly before trying to sleep, but on the other hand, the engineer should avoid going to bed hungry. As fatigue is also influenced by illness, alcohol, etc., it is very important to get more sleep if feeling a little unwell and drink only in moderation between duties (discussed further in the next section). Taking over-the-counter drugs to help sleep should only be used as a last resort. When rotating shifts are worked, it is important that the engineer is disciplined with his eating and sleeping times. Moreover, out of work activities have to be carefully planned. For example, it is obvious that an individual who has been out night-clubbing until the early hours of the morning will not be adequately rested if rostered on an early shift. In the B737 double engine oil loss incident, the error occurred during the night shift. The accident investigation report commented that: “It is under these circumstances that the fragility of the self monitoring system is most exposed because the safety system can be

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jeopardized by poor judgment on the part of one person and it is also the time at which people are most likely to suffer impaired judgment”. A GOOD RULE OF THUMB IS THAT ONE HOUR OF HIGH-QUALITY SLEEP IS GOOD FOR TWO HOURS OF ACTIVITY. Shift working patterns encountered by aircraft maintenance engineers may include three or four days off after the last night shift. It can be tempting to work additional hours, taking voluntary overtime, or another job, in one or more of these days off. This is especially the case when first starting a career in aircraft maintenance engineering when financial pressures may be higher. Engineers should be aware that their vulnerability to error is likely to be increased if they are tired or fatigued, and they should try to ensure that any extra hours worked are kept within reason. Finally, it is worth noting that, although most engineers adapt to shift working, it becomes harder to work rotating shifts as one gets older. 9.5.6 NOISE AND FUMES NOISE The impact of noise on human performance has already been discussed earlier, Section 3 when examining ‘hearing’. To recap, noise in the workplace can have both shortterm and long-term negative effects: it can be annoying, can interfere with verbal communication and mask warnings, and it can damage workers’ hearing (either temporarily or permanently). It was noted that the ear is sensitive to sounds between certain frequencies (20 HZ to 20 KHz) and that intensity of sound is measured in decibels (dB), where exposure in excess of 115 dB without ear protection even for a short duration is not recommended. This equates to standing within a few hundred meters of a moving jet aircraft. General background noise can be ‘filtered out’ by the brain through focused attention(as noted in Chapter 2, Section 3). Otherwise, for more problematic noise, some form of hearing protection(e.g. ear plugs and ear muffs) is commonly used by aircraft maintenance engineers, both on the line and in the hangar, to help the engineer to concentrate. The noise environment in which the aircraft maintenance engineer works can vary considerably. For instance, the airport ramp or apron area is clearly noisy, due to running aircraft engines or auxiliary power units (APUs), moving vehicles and so on. It is not unusual for this to exceed 85 dB - 90 dB which can cause hearing damage if the time of exposure is prolonged.

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The hangar area can also be noisy, usually due to the use of various tools during aircraft maintenance. Short periods of intense noise are not uncommon here and can cause temporary hearing loss. Engineers may move to and from these noisy areas into the relative quiet of rest rooms, aircraft cabins, stores and offices. NOISE CAN BE THOUGHT OF AS ANY UNWANTED SOUND, ESPECIALLY IF IT IS LOUD, UNPLEASANT AND ANNOYING. It is very important that aircraft maintenance engineers remain aware of the extent of the noise around them. It is likely that some form of hearing protection should be carried with them at all times and, as a rule of thumb, used when remaining in an area where normal speech cannot be heard clearly at 2 meters. In their day-to-day work, aircraft maintenance engineers will often need to discuss matters relating to a task with colleagues and also, at the end of a shift, handover to an incoming engineer. Clearly, in both cases it is important that noise does not impair their ability to communicate, as this could obviously have a bearing on the successful completion of the task (i.e. safety). Common sense dictates that important matters are discussed away from noisy areas. FUMES By its nature, the maintenance of aircraft involves working with a variety of fluids and chemical substances. For instance, engineers may come across various lubricants (oils and greases), hydraulic fluids, paints, cleaning compounds and solder. They will also be exposed to aircraft fuel and exhaust. In fact, there is every possibility that an engineer could be exposed to a number of these at any one time in the workplace. Each substance gives off some form of vapour or fumes which can be inhaled by the aircraft maintenance engineer. Some fumes will be obvious as a result of their odour, whereas others have no smell to indicate their presence. Some substances will be benign most of the time, but may, in certain circumstances, produce fumes (e.g. overheated grease or oils, smouldering insulation). Fumes can cause problems for engineers mainly as a result of inhalation, but they can also cause other problems, such as eye irritation. The problem may be exacerbated in aircraft maintenance engineering by the confined spaces in which work must sometimes be carried out (e.g. fuel tanks). Here the fumes cannot dissipate easily and it may be appropriate to use breathing apparatus.

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It may not always be practical to eradicate fumes from the aircraft maintenance engineer’s work place, but where possible, steps should be taken to minimise them. It is also common sense that if noxious fumes are detected, an engineer should immediately inform his colleagues and supervisor so that the area can be evacuated and suitable steps taken to investigate the source and remove them. Apart from noxious fumes that have serious health implications and must be avoided, working in the presence of fumes can affect an engineer’s performance, as he may rush a job in order to escape them. If the fumes are likely to have this effect, the engineer should increase the ventilation locally or use breathing apparatus to dissipate the fumes.

9.5.7 ILLUMINATION In order that aircraft maintenance engineers are able to carry out their work safely and efficiently, it is imperative that their work be conducted under proper lighting conditions. It was noted in earlier that the cones in the retina of the eye require good light to resolve fine detail. Furthermore, colour vision requires adequate light to stimulate the cones. Inappropriate or insufficient lighting can lead to mistakes in work tasks or can increase the time required to do the work. When working outside during daylight, the engineer may have sufficient natural lightto see well by. It is possible however that he may be in shadow (possibly caused by the aircraft) or a building. Similarly, cramped equipment compartments will not be illuminated by ambient hangar lighting. In these cases, additional local artificial lightingis usually required (known as task lighting). At night, aerodromes may appear to be awash with floodlights and other aerodrome lighting, but these are unlikely to provide sufficient illumination for an engineer to be able to see what he is doing when working on an aircraft. These lights are not designed and placed for this purpose. Again, additional local artificial lighting is needed, which may be nothing more than a good torch (i.e. one which does not have a dark area in the centre of the beam). However, the drawback of a torch is that it leaves the engineer with only one hand available with which to work. A light mounted on a headband gets round this problem.

Within the hangar, general area lighting tends to be some distance from the aircraft on which an engineer might work, as it is usually attached to the very high ceiling of these buildings. This makes these lights hard to reach, meaning that they tend to get dusty, making them less effective and, in addition, failed bulbs tend not to be replaced as soon as they go out. In general, area lighting in hangars is unlikely to be as bright as natural daylight

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and, as a consequence, local task lighting is often needed, especially for work of a precise nature (particularly visual inspection tasks). Illumination refers to the lighting both within the general working environment and also in the locality of the engineer and the task he is carrying out. It can be defined as the amount of light striking a surface. A torch can be very useful to the engineer, but Murphy’s Law dictates that the torch batteries will run down when the engineer is across the airfield from the stores. It is much wiser to carry a spare set of batteries than ‘take a chance’ by attempting a job without enough light. It is also important that illumination is available where the engineer needs it (i.e. both in the hangar and on the line). Any supplemental task lighting must be adequate in of its brightness for the task at hand, which is best judged by the engineer. When using task lighting, it should be placed close to the work being done, but should not be in the engineer’s line of sight as this will result in direct glare. It must also be arranged so that it does not reflect off surfaces near where the engineer is working causing indirector reflected glare. Glare of either kind will be a distraction from the task and may cause mistakes. Poor ambient illumination of work areas has been identified as a significant deficiency during the investigation of certain engineering incidents. It is equally important that lighting in ancillary areas, such as offices and stores, is good. Relying on touch when lighting is poor is no substitute for actually being able to see what you are doing. If necessary, tools such as mirrors and borescopes may be needed to help the engineer see into remote areas. An extract from the NTSB report on the Northwest Airlines accident at Tokyo, 1994, illustrates these points: “The Safety Board believes that the "OK to Close" inspector was hindered considerably by the environment of the pylon area. He indicated, for example, that the combination of location of the scaffolding (at a level just below the underside of the wing that forced him into unusual and uncomfortable physical positions) and inadequate lighting from the base of the scaffolding up toward the pylon, hampered his inspection efforts. Moreover, the underside of the pylon was illuminated by portable fluorescent lights that had been placed along the floor of the scaffolding. These lights had previously been used in areas where airplanes were painted, and, as a result, had been covered with the residue of numerous paint applications that diminished their brightness. These factors combined to cause the inspector to view the fuse pin retainers by holding onto the airplane structure with one hand, leaning under the bat wing doors at an angle of at least 30°, holding a flashlight with the other hand pointing to the area, and moving his head awkwardly to face up into the pylon area.” The AAIB report for the BAC 1-11 accident says of the unmanned stores area: “The ambient illumination in this area was poor and the Shift Maintenance Manager had to interpose himself between the carousel and the light source to gain access to the relevant carousel drawers. He did not use the drawer labels, even though he now knew the part number of the removed bolt, but identified what he thought were identical bolts by

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placing the bolts together and comparing them.” He also failed to make use of his spectacles. 9.5.8 CLIMATE AND TEMPERATURE Humans can work within quite a wide range of temperatures and climatic conditions, but performance is adversely affected at extremes of these. Thus, as can be seen in Figure 5.3, when it is either too cold and/or wet or too hot and/or humid, performance diminishes. As has been noted throughout this document, aircraft maintenance engineers routinely work both within the hangar and outside. Clearly, exposure to the widest range of temperature and climate is likely to be encountered outdoors. Here, an engineer may have to work in direct summer sun, strong winds, heavy rain, high humidity, or in the depths of winter. Although hangars must exclude inclement weather, they can be cold and draughty, especially if the hangar doors have to remain open. EASA part 145.A.25 (c) 1 states that “temperatures must be maintained such that personnel can carry out required tasks without undue discomfort.” Unfortunately, in reality, pressure to turn aircraft round rapidly means that some maintenance tasks are not put off until the conditions are more conducive to work. Environmental conditions can affect physical performance. For example, cold conditions make numb fingers, reducing the engineer’s ability to carry out fiddly repairs, and working in strong winds can be distracting, especially if having to work at height (e.g. on staging). Extreme environmental conditions may also be fatiguing, both physically and mentally.

There are no simple solutions to the effects of temperature and climate on the engineer. For example, an aircraft being turned around on the apron cannot usually be moved into the hangar so that the engineer avoids the worst of the weather. In the cold, gloves can be worn, but obviously the gloves themselves may interfere with fine motor skills. In the direct heat of the sun or driving rain, it is usually impossible to set up a temporary shelter when working outside. There was an instance in Scotland, where work on an aircraft was only suspended when it became so cold that the lubricants being used actually froze.

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9.5.9 MOTION AND VIBRATION Aircraft maintenance engineers often make use of staging and mobile access platforms to reach various parts of an aircraft. As these get higher, they tend to become less stable. For example when working at height on a scissors platform or ‘cherry picker’, applying force to a bolt being fixed to the aircraft may cause the platform to move away from the aircraft. The extent to which this occurs does not just depend on the height of the platform, but its design and serviceability. Any sensation of unsteadiness may distract an engineer, as he may concentrate more on keeping his balance than the task. Furthermore, it is vitally important that engineers use mobile access platforms properly in order to avoid serious injury. Vibration in aircraft maintenance engineering is usually associated with the use of rotating or percussive tools and ancillary equipment, such as generators. Low frequency noise, such as that associated with aircraft engines, can also cause vibration. Vibration between 0.5 Hz to 20 Hz is most problematic, as the human body absorbs most of the vibratory energy in this range. The range between 50-150 Hz is most troublesome for the hand and is associated with Vibratory-induced White Finger Syndrome (VWF). Pneumatic tools can produce troublesome vibrations in this range and frequent use can lead to reduced local blood flow and pain associated with VWF. Vibration can be annoying, possibly disrupting an engineer’s concentration.

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9.5.10 COMPLEX SYSTEMS All large modern aircraft can be described as complex systems. Within these aircraft, there are a myriad of separate systems, many of which themselves may be considered complex, e.g. flying controls, landing gear, air conditioning, flight management computers. Table 5.1 gives an example of the breadth of complexity in aircraft systems. The purpose, composition and function of a simple system is usually easily understood by an aircraft maintenance engineer. In other words, the system is transparent to him. Fault finding and diagnosis should be relatively simple with such systems (although appropriate manuals etc. should be referred to where necessary). With a complex system, it should still be clear to an aircraft maintenance engineer what the system’s purpose is. However, its composition and function may be harder to conceptualize - it is opaque to the engineer. To maintain such complex systems, it is likely that the engineer will need to have carried out some form of system-specific training which would have furnished him with an understanding of how it works (and how it can fail) and what it is made up of (and how components can fail). It is important that the engineer understands enough about the overall functioning of a large, complex aircraft, but not so much that he is overwhelmed by its complexity. Thus, system-specific training must achieve the correct balance between detailed system knowledge and analytical troubleshooting skills. Any complex system can be thought of as having a wide variety of inputs. The system typically performs complex modifications on these inputs or the inputs trigger complex responses. There may be a single output, or many distributed outputs from the system. With complex systems within aircraft, written procedures and reference material become an even more important source of guidance than with simple systems. They may describe comprehensively the method of performing maintenance tasks, such as inspections, adjustments and tests. They may describe the relationship of one system to other systems and often, most importantly, provide cautions or bring attention to specific areas or components. It is important to follow the procedures to the letter, since deviations from procedures may have implication on other parts of the system of which the engineer may be unaware. In modern aircraft, it is likely that the expertise to maintain a complex system may be distributed among individual engineers. Thus, avionics engineers and A&C engineers may need to work in concert to examine completely a system that has an interface to the pilot in the cockpit (such as the undercarriage controls and indications). A single modern aircraft is complex enough, but many engineers are qualified on several types and variants of aircraft. This will usually mean that he has less opportunity to become familiar with one type, making it even more important that he sticks to the prescribed procedures and refers to the reference manual wherever necessary.

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There is a particular vulnerability where tasks are very similar between a number of different aircraft (e.g. spoiler systems on the A320, B757 and B767), and may be more easily confused if no reference is made to the manual. When working with complex systems, it is important that the aircraft maintenance engineer makes reference to appropriate guidance material. This typically breaks down the system conceptually or physically, making it easier to understand and work on.

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9.5.11 HAZARDS IN THE WORKPLACE Hazards in the workplace tend to be a health and safetyissue, relating to the protection of individuals at work. All workplaces have hazards and aircraft maintenance engineering is no exception. Health and safety is somewhat separate from human factors and this chapter therefore gives only a very brief overview of the issues relating the aircraft maintenance engineering.

POTENTIAL HAZARDS IN AIRCRAFT MAINTENANCE ENGINEERING There are may potential hazards in the aircraft maintenance industry and it is impossible to list them all here. However, a thorough health and safety appraisal will reveal the hazards. Physical hazards may include:  very bright lights (e.g. from welding)  very loud sounds (sudden or continuous)  confined or enclosed areas  working at significant heights  noxious substances (liquids, fumes, etc.)  excessive temperature (i.e. too cold or too hot)  moving equipment, moving vehicles and vibration RELEVANT LEGISLATION AND THE MAINTENANCE ORGANIZATION’S RESPONSIBILITIES Industrial Safety Division of the Labour Department is responsible to carry out the oversight to measure the environment factors such as dust, noise and light to find out whether the physical environment of the Factory is favorable for the employees. The major role of the industrial Safety Division is the enforcement of Factories Ordinance and by doing so the occupational Safety, health and welfare of the employees engaged in Factories and Worksites are being ensured. Measures have been taken to amend this ordinance which is presently confined only to Factories and Worksites, so that it will cover all Workplaces and Offices. The employer is also obliged to have a health and safety policy bring to the notice of all its employees this policy together with the organization and arrangements in force for carrying out that policy. Thus, in an aircraft maintenance organization, the health and safety policymight include statements applicable to the organization such as the need to:

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 Carry out assessments of work including inspections to determine Health and Safety risks  Provide safe working practices and procedures for plant, machinery, work equipment, materials and substances  Inform employees and other persons including temporary workers of any risk  Provide suitable training and/or instruction to meet any Health and Safety risks  Develop and introduce practices and procedures to reduce risks to Health and Safety including the provision of special protective devices and personal protective equipment  Provide for the welfare of employees  Discuss with and consult employee representatives on Health and Safety matters Maintenance organizations should appoint someone with health and safety responsibilities. If hazards cannot be removed from the workplace, employees should be made aware that they exist and how to avoid them. This can be affected through training and warning signs. To be effective, warnings signs must:  clearly identify the hazard(s)  describe the danger (i.e. electric shock, radiation, etc)  inform employees what to do or not to do The sign must attract an engineer’s attention, it must be visible and it must be understandable to the people it is aimed at. Additionally, in the maintenance industry, it must be durable enough to remain effective, often for years, in areas where dust and the elements can be present. Positive recommendations are more effective than negative ones. For example, the statement "Stay behind yellow line on floor" is better than "Do not come near this equipment". Warning signs should contain a single word indicating the degree of risk associated with the hazard: DANGER denotes that the hazard is immediate and could cause grave, irreversible damage or injury. CAUTION indicates a hazard of lesser magnitude. The sign should also detail how to avoid or manage the risk. CAUTION signs are generally yellow and black. DANGER signs use red, black and white.

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ENGINEER’S INDIVIDUAL RESPONSIBILITIES The legislation notes that every individual in a workplace also has health and safety responsibilities. Thus, in an aircraft maintenance organization, the health and safety policy might include statements applicable to engineers such as the need to:  Take reasonable care of the health and safety of themselves and others who may be affected by their acts or omissions at work  Co-operate with the maintenance organization to ensure that statutory requirements concerning health and safety at work are met  Work in accordance with any safety instruction and/or training received  Inform their supervisor or management of work situations that represent an immediate or potential danger to health and safety at work and any shortcomings in protection arrangements  Not interfere intentionally or recklessly with, nor misuse, anything provided in the interests of health and safety The attitude of an individual engineer, team or maintenance organization (i.e. organizational culture) can have a significant impact on health and safety. Individuals who display an anti-authority attitude, are impulsive, or reckless are a danger in aircraft maintenance. SAFETY IN THE WORKING ENVIRONMENT Engineers should ensure that they keep the working environment safe. Clutter, rubbish, etc. is not only a nuisance to others, but can constitute a danger (e.g. a trip hazard, fire hazard, etc.). In addition, engineers should be careful when working on the line not to leave objects when a job has been completed. Foreign Object Damage (FOD) is a risk to aircraft operating at an airfield. SAFETY WHEN WORKING ON AIRCRAFT Before operating or working on aircraft system, an engineer should carry out clearance checks around moveable surfaces (e.g. flying controls, landing gear, flaps, etc.). Deactivation procedures should be followed (e.g. pull circuit breakers, isolate valves, disconnect power, etc.). Notification of deactivation through the provision of adequate placard in key locations is essential to inform others of system status. DEALING WITH EMERGENCIES Careful handling of health and safety in the maintenance environment should serve to minimize risks. However, should health and safety problems occur, all personnel should

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know as far as reasonably practical how to deal with emergency situations. Emergencies may include:  An injury to oneself or to a colleague  A situation that is inherently dangerous, which has the potential to cause injury (such as the escape of a noxious substance, or a fire) Appropriate guidance and training should be provided by the maintenance organization. The organization should also provide procedures and facilities for dealing with emergency situations and these must be adequately communicated to all personnel. Maintenance organizations should appoint and train one or more firstaiders. Emergency drills are of great value in potentially dangerous environments. Aircraft maintenance engineers should take part in these wherever possible. Knowledge of what to do in an emergency can save lives. THE BASIC ACTIONS IN AN EMERGENCY ARE TO:  Stay calm and assess the situation  Observe what has happened  Look for dangers to oneself and others  Never put oneself at risk  Make the area safe  Protect any casualties from further danger  Remove the danger if it is safe to do so (i.e. switching off an electrical current if an electrocution has occurred)  Be aware of ones own limitations (e.g. do not fight a fire unless it is practical to do so)  Assess all casualties to the best of ones abilities (especially if one is a qualified firstaider)  Call for help  Summon help from those nearby if it is safe for them to become involved  Call for local emergency equipment (e.g. fire extinguisher)  Call for emergency services (ambulance or fire brigade, etc.)  Provide assistance as far as one feels competent to.

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9.5.12 LACK OF MANPOWER EASA part 145.A.30 (d) state that The organization shall have a maintenance man-hour plan showing that the organization has sufficient staff to plan, perform, supervise, inspect and quality monitor the organization in accordance with the approval. In addition the organization shall have a procedure to reassess work intended to be carried out when actual staff availability is less than the planned staffing level for any particular work shift or period. Lack of manpower or insufficient man power will lead to overloading existing staff. In such situation it is required to re-assess the work and necessary steps should be taken to differ the work which does not need immediate attention. Lack of resources is unlikely to be a problem in most organization but there will be times when the person might say ‘I wish I had just one more person to help us with this job’ 9.5.13 DISTRACTIONS AND INTERRUPTIONS Distractions in the engineering business are common. Irrespective of whether the distraction is home life or just a friend at work interrupting when work is done, distractions have been cited on many occasions as the reason for checks or steps being missed during an engineering process. Following steps will help maintenance staff to minimise the effects of distraction Always finish the job or unfasten the connection Mark the uncompleted work Lockwire where possible or torque seal Double inspect by another or self When return to the job always go back few steps Use a detailed check sheet

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MODULE 9

HUMAN FACTORS

SUB MODULE 9.6

PROCEDURES, INFORMATION, TOOLS AND PRACTICES

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CONTENTS 9.6 Procedures, Information, Tools And Practices ....................... 6-1 9.6.1 visual Inspection .................................................................... 6-1 9.6.2 Work logging and recording................................................... 6-2 9.6.3 Procedure – practice / mismatch / norms ............................. 6-3 Procedure Usage ............................................................................. 6-5 9.6.4 Technical documentation – access and quality ..................... 6-6

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9.6 PROCEDURES, INFORMATION, TOOLS AND PRACTICES 9.6.1 VISUAL INSPECTION Visual inspection is one of the primary methods employed during maintenance to ensure the aircraft remains in an airworthy condition. Aircraft maintenance engineers may use magnifiers and borescopes to enhance their visual capabilities. The engineer may accompany his visual inspection by examining the element using his other senses (touch, hearing, smell, etc.). He may also manipulate the element being inspected to make further judgments about its condition. For instance, he might feel a surface for unevenness, or push against it to look for any unanticipated movement. As highlighted earlier (“Vision and the Aircraft Maintenance Engineer”), good eyesight is of prime importance in visual inspection, and it was noted that the UK CAA have provided some guidance on eyesight in AWN47. Amongst other things, this calls for glasses or lenses to be used where prescribed and regular eyesight checks to be made. Visual inspection is often . Although the engineer’s vision is important, he also has to make judgments about what he sees. To do this, he brings to bear training, experience and common sense. Thus, reliable visual inspection requires that the engineer first sees the defect and then actually recognizes that it is a defect. Of course, experience comes with practice, but telltale signs to look for can be ed on by more experienced colleagues. There are various steps that an engineer can take to help him carry out a reliable visual inspection. The engineer should: ensure that he understands the area, component or system he has been asked to inspect (e.g. as specified on the work card)locate the corresponding area, component or system on the aircraft itself make sure the environment is conducive to the visual inspection task (considering factors described earlier, such as lighting, access, etc.) conduct a systematic visual search, moving his eyes carefully in a set pattern so that all parts are inspected examine thoroughly any potential degradation or defect that is seen and decide whether it constitutes a problem record any problem that is found and continue the search a few steps prior to where he left off

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9.6.2 WORK LOGGING AND RECORDING `This is one of the most critical aspects of communication within aviation maintenance, since inadequate logging or recording of work has been cited as a contributor to several incidents. Even if engineers think that they are going to complete a job, it is always necessary to keep the record of work up-to-date just in case the job has to be handed over. This may not necessarily be as a result of a shift change, but might be due to a rest break, illness, the need to move to another (possibly more urgent) task, etc. Basic rules of thumb to help aircraft maintenance engineers minimize poor communication are: think about what you want to say before speaking or writing speak or write clearly listen or read carefully seek clarification wherever necessary In the B737 double engine oil loss incident in February 1995, for instance, one of the AAIB conclusions was: “…the Line Engineer…had not made a written statement or annotation on a work stage sheet to show where he had got to in the inspections”. The reason for this was because he had intended completing the job himself and, therefore, did not consider that detailed work logging was necessary. However, this contributed towards the incident in that: “the Night Base Maintenance Controller accepted the tasks on a verbal handover *and] he did not fully appreciate what had been done and what remained to be done”. The exact manner in which work should be logged tends to be prescribed by company procedures. It is usually recorded in written form. However, there is no logical reason why symbols and pictures should not also be used to record work or problems, especially when used for handovers. There are many cases where it may be clearer to draw a diagram rather than to try to explain something in words (i.e. ‘a picture is worth a thousand words’).

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The key aspects of work logging and recording are captured in the CAA’s Airworthiness Notice No. 3 (AWN3). This states: “In relation to work carried out on an aircraft, it is the duty of all persons to whom this Notice applies to ensure that an adequate record of the work carried out is maintained. This is particularly important where such work carries on beyond a working period or shift, or is handed over from one person to another. The work accomplished, particularly if only disassembly or disturbance of components or aircraft systems, should be recorded as the work progresses or prior to undertaking a disassociated task. In any event, records should be completed no later than the end of the work period or shift of the individual undertaking the work. Such records should include ‘open’ entries to reflect the remaining actions necessary to restore the aircraft to a serviceable condition prior to release. In the case of complex tasks which are undertaken frequently, consideration should be given to the use of pre-planned stage sheets to assist in the control, management and recording of these tasks. Where such sheets are used, care must be taken to ensure that they accurately reflect the current requirements and recommendations of the manufacturer and that all key stages, inspections, or replacements are recorded.” New technology is likely to help engineers to record work more easily and effectively in the future. ICAO Digest No.12: “Human Factors in Aircraft Maintenance and Inspection”, refers to hand-held computers and an Integrated Maintenance Information System (IMIS). It points out that these devices are likely to encourage the prompt and accurate recording of maintenance tasks. Modern technology is also being implemented to improve the transfer of information in maintenance manuals to worksheets and work cards. These help to communicate pertinent information to engineers in an accessible and useable format. A contributory factor in the B737 double engine oil loss incident was that the information which should have prompted the engineer to carry out a post-inspection idle engine run to check for leaks was in the maintenance manual but not carried over to the task cards. 9.6.3 PROCEDURE – PRACTICE / MISMATCH / NORMS Poorly designed procedures are a common source of maintenance error. In the nuclear industry, for example, nearly 70 per cent of all human performance problems have been traced to bad procedures." These were procedures that gave the wrong information, were inappropriate or unworkable in the present situation, were not known about, were out of date, could not be found, could not be understood or simply had not been written to cover this job. Poor procedures not only breed mistakes, they are a major factor leading to violations.

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It would be wrong to think that most violations were due to bloody - mindedness on the part of the workforce. As we have already seen, situational or necessary violations arise because people want to get the job done, but the tools or the situation make it impossible to do the job and comply with the procedures. In a study of European airlines, it was found that unclear task cards or vague procedures were among the main reasons for deviations from maintenance procedures. Violations are deliberate acts. People weigh up the costs and benefits of noncompliance and when the perceived benefits exceed the perceived costs, they are likely to violate. This has been called mental economics, and the credit and debit sides of the mental 'balance sheet' are shown in Table 6.1. For many acts of non-compliance, experience shows that violating is an easier way of working and brings no obvious bad effects. In short, the benefits of non-compliance are often seen to outweigh the costs. The study of European airline mechanics found that the most common reason for non-compliance with procedures was that there was a moreconvenient or quicker wav of working. The management challenge here is not so much to increase the costs of violating by stiffer penalties, but to try to increase the perceived benefits of compliance. And that means having procedures that are workable and that describe the quickest and most efficient ways of doing the job. Any lack of trust caused by inappropriate or clumsy procedures will increase the perceived benefits of violating. Indeed, as shown earlier, the job can only be done in some cases by deviating from the procedures, particularly if the formal procedure cannot be followed in the time allowed. Even if everybody knows that the procedures need to be improved, the formal change system may be so slow and unwieldy that it is more expedient to turn a blind eye to the inevitable violations. This has been referred to as the 'double standard of task performance' and is one of the most difficult issues facing maintenance managers.

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PROCEDURE USAGE There, are many reasons why people choose not to use written procedures-not the least of which is that it is very hard to read and do the job at the same time. It also depends on how the workforce perceives the risks associated with a particular task. Table below shows the results of a survey of procedure usage in a large petrochemical plant."

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The first numbers given show the extent to which the workforce said they used procedures in regard to particular kinds of activity. According to this, safety- and qualitycritical jobs were associated with a high usage, while solving problems (even safety-critical ones) and maintenance work involved a much lower usage- The numbers in brackets show estimates of actual usage in these various categories. These estimates are based on the finding that only 58% of the people surveyed (over 4000) said that they have the procedures open and in front them while they are actually carrying out jobs. In many highly proceduralized industries, it is common for the workforce to write their own procedures as to how jobs should be done. These are jealously, guarded and ed on to new of the work group. They are generally known as 'black books'. The procedure-usage survey found that 56 per cent of operators used informal procedures, as did a Startling 51% of managers. The survey also sought the reasons why people chose not to comply with procedures. The principal factors are listed below. If followed to the letter, the job would not get done. People are not aware that a procedure exits. People prefer to rely on their own skills and experience. People assume that they know what is in the procedure. 9.6.4 TECHNICAL DOCUMENTATION – ACCESS AND QUALITY Maintenance jobs typically start and finish with documentation. Documents not only convey instructions about task performance, but also play an important part in communication by recording the completion of tasks and the extent of system disturbance. A study of the normal day-to-day activities of airline maintenance personnel found that for much of the time they were not touching aircraft at all, but were using fiche readers, technical logs, task cards and maintenance manuals, or were g off tasks.' The more unfamiliar the task, the more time was spent dealing with documentation. Documentation may guide performance on new or unfamiliar tasks, but as people become more familiar with a task they are less likely to refer to the paperwork. This has its risks, particularly, if procedures change. Given the importance of paper records in maintenance, it is not surprising that poorly designed documents lie at the heart of many incidents. Procedures that are ambiguous, wordy or repetitive are likely to promote errors. Procedures that are

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unworkable or unrealistic are likely to promote violations. While re-writing an organization's documentation may not be a feasible short-term objective, some improvements can be made incrementally. Simplified English, for example, can make the language of maintenance documentation clearer and more accessible, particularly in the case of staff for whom English is a second language. Even small improvements in page layout, diagrams and warnings can help to reduce errors. For example, many companies print maintenance documentation in upper case, even though it has been known for many years that such text is more difficult to read than words written in the usual mixture of lower and upper case. Replacing blocks of upper case text with normal mixed-case text can increase reading speed by 14%.

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MODULE 9

HUMAN FACTORS

SUB MODULE 9.7

COMMUNICATION

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CONTENTS 9.7 COMMUNICATION .................................................................... 7-1 Within and Between Teams ........................................................ 7-1 Modes of Communication .......................................................... 7-1 Verbal and Written Communication........................................... 7-2 Non-verbal Communication........................................................ 7-3 Communication within Teams .................................................... 7-3 Communication between Teams ................................................ 7-4 Communication Problems .......................................................... 7-4 9.7.1 Shift / Task handover ............................................................. 7-5 BASE MAINTENANCE SHIFT HANDOVER SYSTEM ....................... 7-6 LINE SHIFT HANDOVER PROCEDURE .......................................... 7-7 Aircraft Maintenance Documents .............................................. 7-8 Verbal Communication between LAE'S; ..................................... 7-8 LINE STATION SHIFT HANDOVER SYSTEM .................................. 7-8 9.7.2 Dissemination of Information ................................................ 7-9 9.7.3 Cultural differences..............................................................7-10 Safety Culture ...........................................................................7-11

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9.7 COMMUNICATION Good communication is important in every industry. In aircraft maintenance engineering, it is vital. Communication, or more often a breakdown in communication, is often cited as a contributor to aviation incidents and accidents. This chapter examines the various aspects of communication that affect the aircraft maintenance engineer.

WITHIN AND BETWEEN TEAMS As noted in previous chapters, aircraft maintenance engineers often work as teams. Individuals within teams exchange information and need to receive instructions, guidance, etc. Moreover, one team will have to on tasks to another team at shift handover. An engineer needs a good understanding of the various processes of communication, as without this, it is impossible to appreciate how communication can go wrong.

MODES OF COMMUNICATION We are communicating almost constantly, whether consciously or otherwise. An aircraft maintenance engineer might regularly communicate:  information  ideas  feelings  attitudes and beliefs As the senderof a message, he will typically expect some kind of responsefrom the person he is communicating with (the recipient), which could range from a simple acknowledgement that his message has been received (and hopefully understood), to a considered and detailed reply. The response constitutes . Communication is defined in the Penguin Dictionary of Psychology as: “The transmission of something from one location to another. The ‘thing’ that is transmitted may be a message, a signal, a meaning, etc. In order to have communication both the transmitter and the receiver must share a common code, so that the meaning or information contained in the message may be interpreted without error”.

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As can be seen in the above definition, communication can be:  verbal/spoken - e.g. a single word, a phrase or sentence, a grunt  written/textual - e.g. printed words and/or numbers on paper or on a screen, hand written notes  non-verbal –  graphic - e.g. pictures, diagrams, hand drawn sketches, indications on a cockpit instrument  symbolic - e.g. ‘thumbs up’, wave of the hand, nod of the head  body language - e.g. facial expressions, touch such as a pat on the back, posture

VERBAL AND WRITTEN COMMUNICATION Generally speaking, verbal and written communication are purposeful. For a spoken or written message to be understood, the sender has to make sure that the receiver:  is using the same channelof communication  recognizes and understands his language  is able to make sense of the message’s meaning The channel of communication is the medium used to convey the message. For spoken communication, this might be face-to-face, or via the telephone. Written messages might be notes, memos, documents or e-mails. In the UK it is expected that aircraft maintenance engineers will communicate in English. However, it is also vital that the message codingused by the sender is appreciated by the recipient so that he can decodethe message accurately. This means that engineers must have a similar knowledge of technical language, jargon and acronyms. Assuming the channel and language used are compatible, to extract meaning, the engineer has to understand the contentof the message. This means that it has to be clear and unambiguous. The message must also be appropriate to the context of the workplace and preferably be compatible with the receiver’s expectations. Where any ambiguityexists, the engineer must seek clarification.

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NON-VERBAL COMMUNICATION Non-verbal communication can accompany verbal communication, such as a smile during a face-to-face chat. It can also occur independently, for instance a colleague may on his ideas by using a sketch rather than the use of words. It can also be used when verbal communication is impossible, such as a nod of the head in a noisy environment. Non-verbal communication is also the predominant manner by which systems communicate their status. For instance, most displays in the aircraft cockpit present their information graphically. Body language can be very subtle, but often quite powerful. For example, the message “No” accompanied by a smile will be interpreted quite differently from the same word said whilst the sender scowls.

COMMUNICATION WITHIN TEAMS Individual aircraft maintenance engineers need to communicate:  before starting a task - to find out what to do  during a task - to discuss work in progress, ask colleagues questions, confirm actions or intentions, or to ensure that others are informed of the maintenance state at any particular time  at the end of a task - to report its completion and highlight any problems Spoken communication makes up a large proportion of day-to-day communication within teams in aircraft maintenance. It relies both on clear transmission of the message (i.e. not mumbled or obscured by background noise) and the ability of the recipient of the message to hear it (i.e. active listening followed by accurate interpretation of the message). Good communication within a team helps to maintain group cohesion. It is much less common for individuals within teams to use written communication. They would however be expected to obtain pertinent written information communicated by service bulletins and work cards and to complete documentation associated with a task.

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COMMUNICATION BETWEEN TEAMS Communication between teams is critical in aircraft maintenance engineering. It is the means by which one team es on tasks to another team. This usually occurs at shift handover. The information conveyed will include:  tasks that have been completed  tasks in progress, their status, any problems encountered, etc.  tasks to be carried out  general company and technical information Communication between teams will involve ing on written reports of tasks from one shift supervisor to another. Ideally, this should be backed up by spoken details ed between supervisors and, where appropriate, individual engineers. This means that, wherever necessary, outgoing engineers personally brief their incoming colleagues. The written reports (maintenance cards, procedures, work orders, logs, etc.) and warning flags / placards provide a record of work completed and work yet to be completed - in other words, they provide traceability. Furthermore, information communicated at shift handover ensures good continuity. It is important that handovers are not rushed, so as to minimize omissions.

COMMUNICATION PROBLEMS There are two main ways in which communication can cause problems. These are lack of communication and poor communication. The former is characterised by the engineer who forgets to on pertinent information to a colleague, or when a written message is mislaid. The latter is typified by the engineer who does not make it clear what he needs to know and consequently receives inappropriate information, or a written report in barely legible handwriting. Both problems can lead to subsequent human error. Spoken messages provide considerable flexibility and informality to express work-related matters when necessary. The key to such communication is to use words effectively and obtain to make sure your message has been heard and understood. Communication also goes wrong when one of the parties involved makes some kind of assumption. The sender of a message may assume that the receiver understands the he has used. The receiver of a message may assume that the message means one thing when in fact he has misinterpreted it. Assumptions may be based on context and expectations, which have already been mentioned. Problems with assumptions can be minimized if messages are unambiguous and proper is given.

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9.7.1 SHIFT / TASK HANDOVER EASA part 145.A.47 (c) states that: When it is required to hand over the continuation or completion of maintenance tasks for reasons of a shift or personnel changeover, relevant information shall be adequately communicated between outgoing and incoming personnel. AMC 145.A.47 (c) state that: The primary objective of the changeover / handover information is to ensure effective communication at the point of handing over the continuation or completion of maintenance actions. Effective task and shift handover depends on three basic elements:  The outgoing person’s ability to understand and communicate the important elements of the job or task being ed over to the incoming person.  The incoming person’s ability to understand and assimilate the information being provided by the outgoing person.  A formalized process for exchanging information between outgoing and incoming persons and a planned shift overlap and a place for such exchanges to take place. SHIFT / TASK HANDOVER PROCEDURES [MOE AND EPM EXTRACTS] Objective: The objective of this procedure is to have in place an effective method of communicating relevant information at the point of handing over the continuation or completion of a maintenance task. General Description:  A formalized process for exchange information between outgoing and incoming persons/teams in charge of maintenance needs to be in place. The system shall clearly identify completed and remaining work to be done.  The Handover from one shift to another will be performed by the responsible approval holder using appropriate handing over sheets.  The Handover of a task from one person to another will be performed by the person handling over the work by personally explaining the work having been incompletely performed to the person taking over and by g off the performed work on the Job Card or other relevant document accordingly. Responsibility: Line station approval holders & Duty Engineers are responsible for developing the process.

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BASE MAINTENANCE SHIFT HANDOVER SYSTEM Objective: The purpose of this procedure is to describe the method used by Base Maintenance to assure that continuous maintenance tasks can be transferred between staff during shift changes. GENERAL PROCEDURE:  Whilst several documents and aids are used to accomplish an effective shift handover, it is imperative that all maintenance tasks undertaken on an aircraft within Base Maintenance be recorded in the relevant aircraft technical log, cabin log, non-routine cards and other associated documents issued by Maintenance Planning Section.  Base Maintenance operates in shift systems dependent on type of work undertaken as laid down by the Maintenance Planning section as follows: During letter 'C' check - morning shifts of 12 hours will be regular pattern but Night shift may be arranged to cater for specific tasks or to cater for schedule slippage.  Current heavy maintenance shift pattern, opportunity for direct handover is not always possible, in lieu, reliance on verbal, e-mail and facsimile facilities are used to ascertain complete and thorough handover between the Duty Engineers/check controller involved.  Shift handover is accomplished by the following aids:  Base Maintenance handover Log  The shift duty engineer completes this log for each roster duty period covered for all aircraft under Base Maintenance control.  Verbal Communications between Duty engineers.  Verbal discussions regarding information contained in the Base maintenance log especially those involved in heavy maintenance projects  Aircraft Maintenance Documents Handover of technical nature involving aircraft maintenance task ultimately will only be dependent and relied upon entries made in the relevant aircraft technical log bock, cabin logbook, non routine cards and other related documents issued by Maintenance Planning section e.g. SWC, SI etc.  Verbal Communication Between LAE'S; Due to nature and extent of maintenance task usually undertaken by Base Maintenance, verbal communication between LAEs handing over maintenance task is important however it is imperative all tasks undertaken be recorded and certified when completed and all open entries be subject of discussion especially all salient and related maintenance task involved to complete said tasks.

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 Aircraft Daily Allocation Sheet ; This sheet displays the aircraft that will be handled by Base Maintenance Operations. It details the aircraft arrival/departure data as well as location and shows the mechanics and LAEs allocated to undertake the handling. Additional Information may be annotated by the Duty engineer for the LAE/Shift leader reference.  Base Maintenance Handover Log: This log is completed by the Duty Engineer as a handover of relevant activities that occurred on his shift to the incoming Duty Engineer for information and action as necessary. This log forms the basis of the base operational handover tool and the Duty engineer has the prerogative of involving the LAE nominated to function as a check coordinator to participate in this handover session should it be deemed necessary. This option is to cater for letter check days where extensive work is planned to facilitate smoother handover. Base Maintenance log will be retained for at least one year and stored in the Base Maintenance office. Status of up to 2 aircraft inputs per page can be tracked, however its left to the discretion of the Duty Engineer to continue on a second page should an overflow of information dictate this need. Each page will be signed by the outgoing Duty engineer shift thus ending his duty period and completing his handover to the incoming shift. Records: the Base Maintenance handover book shall be maintained by the Duty Engineers LINE SHIFT HANDOVER PROCEDURE Objective: The purpose of this procedure is to describe the method used by Line Maintenance to assure that continuous maintenance tasks can be transferred between staff during shift changes. GENERAL PROCEDURE:  Whilst several documents and aids are used to accomplish an effective shift handover, it is imperative that all maintenance tasks undertaken on an aircraft within Line Maintenance be recorded in the relevant aircraft technical log, cabin log, cards and other associated documents issued by Maintenance Planning Section.  Line Maintenance operates in shift systems which changes every 12 hours.  Shift handover is accomplished by the following aids:

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 Line Maintenance Duty Engineer handover Log. The shift duty engineer completes this log for each roster duty period covered for all aircraft under Line Maintenance.  Continuation / Supplementary work sheets and NRC  Verbal Communications between Engineers / Approval holders.

AIRCRAFT MAINTENANCE DOCUMENTS Handover of technical nature involving aircraft maintenance task ultimately will only be dependent and relied upon entries made in the relevant aircraft technical logbook, cabin logbook, non routine cards Continuation/ supplementary work card and other related documents issued by Maintenance Planning section e.g. SWC, SI etc.

VERBAL COMMUNICATION BETWEEN LAE'S; Due to nature and time restrictions of maintenance task usually undertaken by Line Maintenance, verbal communication between LAEs handing over maintenance task is important however, it is imperative all tasks undertaken be recorded and certified when completed and all open entries be subject of discussion especially all salient and related maintenance task involved to complete said tasks. LINE STATION SHIFT HANDOVER SYSTEM Objective:The purpose of this procedure is to describe the method followed at Line Stations to record activities during a work shift and to handover relevant information to the incoming shift. GENERAL PROCEDURE:  Recording and handover is accomplished by means of a Station Log Book  The Log Book is completed by the Station Engineer as a handover of relevant activities that occurred on his shift to the incoming Station Engineer for information and action as necessary.  The log is made up of a Booklet consisting of A4 paper half a page is dedicated per shift.  At the completion of the shift the Log Book will be needs to be signed off by the out going Engineer. Records: Completed Log Books will be retained at the Station for six months.

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9.7.2 DISSEMINATION OF INFORMATION As highlighted earlier, both the individual engineer and the organization in which he works have a shared responsibility to keep abreast of new information. Good dissemination of information within an organization forms part of its safety culture. Typically, the maintenance organization will be the sender and the individual engineer will be the recipient. An aircraft maintenance engineer or team of engineers need to plan the way work will be performed. Part of this process should be checking that all information relating to the task has been gathered and understood. This includes checking to see if there is any information highlighting a change associated with the task (e.g. the way something should be done, the tools to be used, the components or parts involved) There should normally be someone within the maintenance organization with the responsibility for disseminating information. Supervisors can play an important role by ensuring that the engineers within their team have seen and understood any communicated information. Communication is an active process whereby both the organization and engineer have to play their part. It is imperative that engineers working remotely from the engineering base (e.g. on the line) familiarize themselves with new information (on notice boards, in maintenance manuals, etc.) on a regular basis. Poor dissemination of information was judged to have been a contributory factor to the Eastern Airlines accident in 1983. The NTSB accident report stated: “On May 17, 1983, Eastern Air Lines issued a revised work card 7204 [master chip detector installation procedures, including the fitment of O-ring seals+. … the material was posted and all mechanics were expected to comply with the guidance. However, there was no supervisory follow-up to insure that mechanics and foremen were incorporating the training material into the work requirements… Use of binders and bulletin boards is not an effective means of controlling the dissemination of important work procedures, especially when there is no ability system in place to enable supervisors to ensure that all mechanics had seen the applicable training and procedural information.”

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9.7.3 CULTURAL DIFFERENCES There can be a degree of mistrust of anything new in the workplace, (e.g. an individual ing a company whose expertise has not yet been proven, or contracting out maintenance to another company, etc.). There may be a tendency for groups within organization and the organization itself to think that their own methods are the best and that others are not as good. This viewpoint is known as the group’s or organization's culture. Figure 7.1 indicates that there can be an overall organizational culture, and a number of different ‘sub-cultures’, such as safety culture, professional/technical culture, etc. It is possible for cultural differences to exist between sites or even between shifts within the same organization. The prevailing culture of the industry as a whole also influences individual organizations. Culture is not necessarily always generated or driven from the top of an organization (as one might think), but this is the best point from which to influence the culture.

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SAFETY CULTURE The ICAO Human factors Digest No. 10, “Human Factors, Management and Organization” (Circular 247), discusses corporate culture and the differences between safe and unsafe corporate cultures. Gary Eiff from Purdue University discusses safety culture in his paper “Organizational Culture and its Effect on Safety”. He suggests that “A safety culture exists only within an organization where each individual employee, regardless of their position, assumes an active role in error prevention”, stressing that “Safety cultures do not …spring to life simply at the declaration of corporate leaders”. The culture of an organization can be described as ‘the way we do things here’. It is a group or company norm. ICAOHF Digest 10 describes a safety culture as “a set of beliefs, norms, attitudes, roles and social and technical practices concerned with minimizing exposure of employees, managers, customers and of the general public to conditions considered dangerous or hazardous” The culture of an organization can best be judged by what is done rather than by what is said. Organizations may have grand ‘mission statements’ concerning safety but this does not indicate that they have a good safety culture unless the policies preached at the top are actually put into practice at the lower levels. It may be difficult to determine the safety culture of an organization by auditing the procedures and paperwork; a better method is to find out what the majority of the staff actually believe and do in practice. Professor James Reason describes the key components of a safety culture, summarized as follows:  The ‘engine’ that continues to propel the system towards the goal of maximum safety health, regardless of the leadership’s personality or current commercial concerns  Not forgetting to be afraid  Creating a safety information system that collects, analyses and disseminates information from incidents and near-misses as well as from regular proactive checks on the system’s vital signs  A good reporting culture, where staff are willing to report near-misses  A just culture - an atmosphere of trust, where people are encouraged, even rewarded, for providing essential safety related information - but in which they are clear about where the line must be drawn between acceptable and unacceptable behaviour

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 A flexible culture  Respect for the skills, experience and abilities of the workforce and first line supervisors  Training investment  A learning culture - the willingness and the competence to draw the right conclusions from its safety information system, and the will to implement major reforms when their need is indicated

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MODULE 9

HUMAN FACTORS

SUB MODULE 9.8

TEAMWORK

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CONTENTS 9.8. TEAMWORK ............................................................................. 8-1 The Concept of a Team ............................................................... 8-1 Some Advantages and Disadvantages of Team Working ........... 8-1 Important Elements of Team Working ....................................... 8-2 9.8.1 Responsibility ......................................................................... 8-3 Responsibility: Individual and Group .......................................... 8-3 Individual Responsibility ............................................................. 8-4 Group or Team Responsibility .................................................... 8-4 9.8.2 Management, Supervision and Leadership ........................... 8-6 The Management Role................................................................ 8-6 The Supervisory Role .................................................................. 8-6 Characteristics of a Leader.......................................................... 8-7 9.8.3 Decision making ..................................................................... 8-9 Confirmation Bias........................................................................ 8-9 Emotion and Decision Making .................................................... 8-9

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9.8. TEAMWORK THE CONCEPT OF A TEAM A lot has been written on the concept of a team, and it is beyond the scope of this document to give anything but a flavour of this. Teams may comprise a number of individuals working together towards one shared goal. Alternatively, they may consist of a number of individuals working in parallel to achieve one common goal. Teams generally have a recognized leader and one or more follower(s). Whilst safety culture has been discussed from the organizational perspective, the responsibility of the individual should not be overlooked. Ultimately, safety culture is an amalgamation of the attitude, beliefs and actions of all the individuals working for the organization and each person should take responsibility for their own contribution towards this culture, ensuring that it is a positive contribution rather than a negative one. Whereas individualism encourages independence, teams are associated with interdependence and working together in some way to achieve one or more goals. A team could be a group of engineers working on a specific task or the same aircraft, a group working together on the same shift, or a group working in the same location or site. There are natural teams within the aircraft maintenance environment. The most obvious is the supervisor and the engineers working under his supervision. A team could also be a Licensed Aircraft Engineer (LAE) and unlicensed engineers working subject to his scrutiny. A team may well comprise engineers of different technical specialties (e.g. sheet/metal structures, electrical/ electronics/ avionics, hydraulics, etc.). There has been a great deal of work carried out on teamwork, in particular “Crew Resource Management (CRM)” in the cockpit context and, more recently, “Maintenance Resource Management (MRM)” in the maintenance context. The ICAO Human Factors Digest No. 12 “Human Factors in Aircraft Maintenance and Inspection” (ICAO Circular 253), includes a Chapter on team working, to which the reader is directed for further information. SOME ADVANTAGES AND DISADVANTAGES OF TEAM WORKING The discussion on motivation suggests that individuals need to feel part of a social group. In this respect, team working is advantageous. However, the work on conformity suggests that they feel some pressure to adhere to a group’s views, which may be seen as a potential disadvantage. Working as part of a team has a number of potential benefits which include: Individuals can share resources (knowledge, tools, etc.) they can discuss problems and arrive at shared solutions

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they can check each others’ work (either “officially” or “unofficially”) Teams can be encouraged to take ownership of tasks at the working level. This gives a team greater responsibility over a package of work, rather than having to keep referring to other management for authorization, or direction. However, groups left to their own devices need proper leadership. Healthy competition and rivalry between teams can create a strong team identity and encourage pride in the product of a team. Team identity also has the advantage that a group of engineers know one another’s capabilities (and weaknesses). As noted in earlier, if work has to be handed over to another group or team (e.g. shift handover), this can cause problems if it is not handled correctly. If one team of engineers consider that their diligence (i.e. taking the trouble to do something properly and carefully) is a waste of time because an incoming team’s poor performance will detract from it, then it is likely that diligence will become more and rarer over time.

IMPORTANT ELEMENTS OF TEAM WORKING For teams to function cohesively and productively, team need to have or build up certain interpersonal and social skills. These include communication, cooperation co-ordination and mutual COMMUNICATION Communication is essential for exchanging work-related information within the team. For example, a team leader must ensure that a team member has not just heard an instruction, but understood what is meant by it. A team member must highlight problems to his colleagues and/or team leader. Furthermore, it is important to listen to what others say. CO-OPERATION ‘Pulling together’ is inherent in the smooth running of a team. Fairness and openness within the team encourage cohesiveness and mutual respect. Disagreements must be handled sensitively by the team leader. CO-ORDINATION Co-ordination is required within the team to ensure that the team leader knows what his group are doing. This includes delegation of tasks so that all the resources within the team are utilized. Delegated tasks should be supervised and monitored as Page No 8-2





required. The team leader must ensure that no individual is assigned a task beyond his capabilities. Further important aspects of co-ordination are agreement of responsibilities (i.e. who should accomplish which tasks and within what timescale), and prioritisation of tasks. MUTUAL  Mutual is at the heart of the team’s identity. The team leader must engender this in his team. For instance, if mistakes are made, these should be discussed and corrected constructively.  It is worth noting that in many companies, line engineers tend to work as individuals whereas base engineers tend to work in teams. This may be of significance when an engineer who normally works in a hangar, finds himself working on the line, or vice versa. This was the case in the Boeing 737 incident involving double engine oil pressure loss, where the Base Controller took over a job from the Line Maintenance engineer, along with the line maintenance paperwork. The line maintenance paperwork is not designed for recording work with a view to a handover, and this was a factor when the job was handed over from the Line engineer to the Base Controller. 9.8.1 RESPONSIBILITY RESPONSIBILITY: INDIVIDUAL AND GROUP Being an aircraft maintenance engineer is a responsible job. Clearly, the engineer plays a part in the safe and efficient age of the travelling public when they use aircraft. Within aircraft maintenance, responsibility should be spread across all those who play a part in the activity. This ranges from the able manager who formulates policy, through management that set procedures, to supervisors, teams of engineers and individuals within those teams. Flight crew also play a part as they are responsible for carrying out pre-flight checks and walk-around and highlighting aircraft faults to maintenance personnel.

WORKING AS AN INDIVIDUAL OR AS A GROUP Traditionally, in the maintenance engineering environment, responsibility has been considered in of the individual rather than the group or team. This is historical, and has much to do with the manner in which engineers are licensed and the way in which work is certified. This has both advantages and disadvantages. The main advantage to individual responsibility is that an engineer understands clearly that one or more tasks have been assigned to him and it is his job to do them (it can also be a strong incentive to an engineer to do the work correctly knowing that he will be the one held responsible if something goes wrong). The main disadvantage of any emphasis upon personal responsibility is that this

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may overlook the importance of working together as a cohesive team or group to achieve goals. In practice, aircraft maintenance engineers are often assigned to groups or teams in the workplace. These may be shift teams, or smaller groups within a shift. A team may be made up of various engineering trades, or be structured around aircraft types or place of work (e.g. a particular hangar). Although distinct tasks may be assigned to individuals within a team, the responsibility for fulfilling overall goals would fall on the entire team. If someone is considered responsible, they are liable to be called to as being in charge or control of, or answerable for something. INDIVIDUAL RESPONSIBILITY All aircraft maintenance engineers are skilled individuals having undertaken considerable training. They work in a highly professional environment in the UK and generally have considerable pride in their work and its contribution to air safety. All individuals, regardless of their role, grade or qualifications should work in a responsible manner. This includes not only Licensed Aircraft Engineers (LAEs), but non-licensed staff. “The certifying engineer shall be responsible for ensuring that work is performed and recorded in a satisfactory manner...”. Likewise, non-certifying technicians also have a responsibility in the maintenance process. An organization approved in accordance with EASA part 145 must establish the competence of every person, whether directly involved in hands-on maintenance or not. Regulatory Authorities previously ruled that an organisation can make provision on maintenance records or work sheets for the mechanic(s) involved to sign for the work. Whilst this is not the legally required certification under the requirements of EASA part145, it provides the traceability to those who were involved in the job. The LAE is then responsible for any adjustment or functional test and the required maintenance records are satisfied before making the legal certification. GROUP OR TEAM RESPONSIBILITY Group responsibility has its advantages and disadvantages. The advantages are that each member of the group ought to feel responsible for the output of that group, not just their own output as an individual, and ought to work towards ensuring that the whole ‘product’ is safe. This may involve cross-checking others’ work (even when not strictly required), politely challenging others if you think that something is not quite right, etc. The disadvantage of group responsibility is that it can potentially act against safety, with responsibility being devolved to such an extent that no-one feels personally responsible for safety (referred to as diffusion of responsibility). Here, an individual, on his own, may take action but, once placed within a group situation, he may not act if none of

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the other group do so, each member of the group or team assuming that ‘someone else will do it’. Social psychologists have carried out experiments whereby a situation was contrived in which someone was apparently in distress, and noted who came to help. If a person was on their own, they were far more likely to help than if they were in a pair or group. In the group situation, each person felt that it was not solely his responsibility to act and assumed that someone else would do so. Other recognized phenomena associated with group or team working and responsibility for decisions and actions which aircraft maintenance engineers should be aware of are: Inter-group conflict in which, situations evolve where a small group may act cohesively as a team, but rivalries may arise between this team and others (e.g. between engineers and planners, between shifts, between teams at different sites, etc.). This may have implications in of responsibility, with teams failing to share responsibility between them. This is particularly pertinent to change of responsibility at shift handovers, where of the outgoing shift may feel no ‘moral’ responsibility for waiting for the incoming shift to arrive and giving a verbal handover in of the written information on the work cards or task sheets, whereas they might feel such responsibility when handing over tasks to others within their own shift. Group polarization is the tendency for groups to make decisions that are more extreme than the individual ’ initial positions. At times, group polarization results in more cautious decisions. Alternatively, in other situations, a group may arrive at a course of action that is riskier than that which any individual member might pursue. This is known as risky shift. Another example of group polarization is groupthink in which the desire of the group to reach unanimous agreement overrides any individual impulse to adopt proper, rational (and responsible) decision-making procedures. Social loafing has been coined to reflect the tendency for some individuals to work less hard on a task when they believe others are working on it. In other words, they consider that their own efforts will be pooled with that of other group and not seen in isolation. Responsibility is an important issue in aircraft maintenance engineering, and ought to be addressed not only by licensing, regulations and procedures, but also by education and training, attempting to engender a culture of shared, but not diffused, responsibility.

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9.8.2 MANAGEMENT, SUPERVISION AND LEADERSHIP The previous section made frequent reference to the team leader. Management, supervision and leadership are all skills that a team leader requires. Of course, management is also a function within an organization (i.e. those managers responsible for policy, business decisions, etc.), as is the supervisor (i.e. in an official role overseeing a team). Managers and supervisors have a key role to play in ensuring that work is carried out safely. It is no good instilling the engineers and technicians with ‘good safety practice’ concepts, if these are not ed by their supervisors and managers. THE MANAGEMENT ROLE Line Managers, particularly those working as an integral part of the ‘front line’ operation, may be placed in a situation where they may have to compromise between commercial drivers and ‘ideal’ safety practices (both of which are ed down from ‘top management’ in the organization). For example, if there is a temporary staff shortage, he must decide whether maintenance tasks can be safely carried out with reduced manpower, or he must decide whether an engineer volunteering to work a “ghoster” to make up the numbers will be able to perform adequately. The adoption of Safety Management Principles may help by providing Managers with techniques whereby they can carry out a more objective assessment of risk.

THE SUPERVISORY ROLE Supervision may be a formal role or post (i.e. a Supervisor), or an informal arrangement in which a more experienced engineer ‘keeps an eye on’ less experienced staff. The Supervisor is in a position not only to watch out for errors which might be made by engineers and technicians, but will also have a good appreciation of individual engineer’s strengths and weaknesses, together with an appreciation of the norms and safety culture of the group which he supervises. It is mainly his job to prevent unsafe norms from developing, and to ensure that good safety practices are maintained. There can be a risk however, that the Supervisor becomes drawn down the same cultural path as his team without realizing. It is good practice for a Supervisor to step back from the day-to-day work on occasion and to try to look at his charges’ performance objectively. It can be difficult for supervisory and management staff to strike the right balance between carrying out their supervisory duties and maintaining their engineering skills and knowledge (and appropriate authorizations), and they may get out of practice.

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In the UK Air Accidents Investigation Branch (AAIB) investigation reports of the BAC 1- 11, A320 and B737 incidents, a common factor was: “Supervisors tackling long duration, hands-on involved tasks”. In the B737 incident, the borescope inspection was carried out by the Base Controller, who needed to do the task in order to retain his borescope authorization. Also, there is unlikely to be anyone monitoring or checking the Supervisor, because: of his seniority he is generally authorized to sign for his own work (except, of course, in the case where a duplicate inspection is required) he may often have to step in when there are staff shortages and, therefore, no spare staff to monitor or check the tasks he may be ‘closer’ (i.e. more sensitive to) to any commercial pressures which may exist, or may perceive that pressure to a greater extent than other engineers. It is not the intention to suggest that supervisors are more vulnerable to error; rather that the circumstances which require supervisors to step in and assist tend to be those where several of the ‘defences’ have already failed and which may result in a situation which is more vulnerable to error.

CHARACTERISTICS OF A LEADER There are potentially two types of leader in aircraft maintenance: the person officially assigned the team leader role (possibly called the Supervisor), an individual within a group that the rest of the group tend to follow or defer to (possibly due to a dominant personality, etc.). Ideally of course, the official team leader should also be the person the rest of the group defers to. A good leader in the maintenance engineering environment needs to possess a number of qualities: Motivating his team Reinforcing good attitudes and behaviour Demonstrating by example Maintaining the group Fulfilling a management role These will now be examined in a little more detail:

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Page No 8-9






MOTIVATING THE TEAM Just as the captain of a football team motivates his fellow players, the leader of a maintenance team must do likewise. This can be done by ensuring that the goals or targets of the work which need to be achieved are clearly communicated and manageable. For instance, the team leader would describe the work required on an aircraft within a shift. He must be honest and open, highlighting any potential problems and where appropriate encouraging team solutions. REINFORCING GOOD ATTITUDES AND BEHAVIOUR When team work well (i.e. safely and efficiently), this must be recognized by the team leader and reinforced. This might be by offering a word of thanks for hard work, or making a favourable report to senior management on an individual. A good leader will also make sure that bad habits are eliminated and inappropriate actions are constructively criticized. DEMONSTRATING BY EXAMPLE A key skill for a team leader is to lead by example. This does not necessarily mean that a leader must demonstrate that he is adept at a task as his team (it has already been noted that a Supervisor may not have as much opportunity to practice using their skills). Rather, he must demonstrate a personal understanding of the activities and goals of the team so that the team respect his authority. It is particularly important that the team leader establishes a good safety culture within a team through his attitude and actions in this respect. MAINTAINING THE GROUP Individuals do not always work together as good teams. It is part of the leader’s role to be sensitive to the structure of the team and the relationships within it. He must engender a ‘team spirit’ where the team each other and feel responsible for the work of the team. He must also recognize and resolve disputes within the team and encourage co-operation amongst its . FULFILLING A MANAGEMENT ROLE The team leader must not be afraid to lead (and diplomatically making it clear when necessary that there cannot be more than one leader in a team). The team leader is the link between who actually work on the aircraft. He is responsible for co-coordinating the activities of the team on a day-to-day basis, which includes allocation of tasks and delegation of duties. There can be a tendency for team to transfer some of their own responsibilities to the team leader, and he must be careful to resist this.

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In of the relationship between managers, supervisors and engineers, a ‘them and us’ attitude is not particularly conducive to improving the safety culture of an organization. It is important that managers, supervisors, engineers and technicians all work together, rather than against one another, to ensure that aircraft maintenance improves airworthiness. 9.8.3 DECISION MAKING Ideally, we would make all our work-related decisions by following a careful rational process in which we consider all options, evaluate each in turn and then select the best course of action. However, in reality things are somewhat different. We have learned that workplace decisions, including those made by maintenance personnel can be biased and distorted by a range of factors. Sometimes we do not consider all the alternatives, or we take labour-saving mental short cuts to arrive at a solution. Or under emotional or time pressures, our thinking is 'short circuited' so we end up deciding on a course of action which is unsuitable for the situation we are in. Two common decision making problems are outlined below. CONFIRMATION BIAS A powerful factor that can interfere with thinking is the tendency known as 'confirmation bias'. When faced with the need to solve an ambiguous or ill-defined problem, we frequently develop a theory to explain the situation. Once we have such an idea, we tend to search for information that will confirm what we suspect. People rarely attempt to prove themselves wrong, and in fact sometimes disregard information that would contradict their ideas. In troubleshooting a fault, for example, a maintenance staff may decide on the most likely cause, and then attempt to prove that this is the problem. The initial incorrect fault diagnosis can block attempts to consider other possibilities. For instance, an aircraft was reported to be pulling to the left when brakes were applied. The maintenance personnel considered that this was because the brakes were binding on one of the left wheels. After time-consuming and unsuccessful attempts to correct the problem, a quite different problem was eventually discovered. The brakes on the right-hand side were not working. EMOTION AND DECISION MAKING There is a clear link between frustration and aggression. It seems to be hard-wired into people that if a situation keeps frustrating us, we may move into 'aggressive mode', giving us access to extra reserves of strength and motivation. Thousands of years ago, the frustration - aggression link probably helped our ancestors fight wild animals, catch food and solve many other Stone Age problems. Unfortunately, the world in which we live requires careful action more often than brute force, but we still carry within us this primitive problem-solving system. Frustrating circumstances in maintenance such as a lack of proper tools, delays and unreasonable pressures can all combine to cloud judgement with emotion.

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MODULE 9

HUMAN FACTORS

SUB MODULE 9.9

PROFESSIONALISM AND INTEGRITY

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Page No ii






CONTENTS 9.9. PROFESSIONALISM AND INTEGRITY ....................................... 9-1 Concepts of Professionalism ...................................................... 9-1 Defining Professionalism ........................................................... 9-1 9.9.1 Keeping Up-to-Date, Currency .............................................. 9-2 9.9.2 Error provoking behaviour .................................................... 9-4 Person Measures- ...................................................................... 9-4 Measures Designed to Reduce Violations ................................. 9-7 9.9.3 Assertiveness ........................................................................ 9-7

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9.9. PROFESSIONALISM AND INTEGRITY CONCEPTS OF PROFESSIONALISM Professionals are characterized as persons with a high degree of  competence in their field  control (both in authority and ability) to make decisions based on their competence  commitment to the greater public and  being central to the operation of the larger enterprise. Two factors, assertiveness and stress management, have emerged as most effective in ing such professionalism among aircraft maintenance staff. Competence, control, commitment, and centrality of the professional are seen to be ed by the ability and willingness to speak up, even in the face of adversity and social pressure. Likewise the documented willingness of professional aviation maintenance staff to actively mitigate the effects of stresses and strains on their decision-making abilities s and enhances their professionalism and their safety performance. DEFINING PROFESSIONALISM When people receive their mechanic certificate or their maintenance engineer's license, they become part of a unique profession. They receive certain very important privileges and carry a tremendous amount of responsibility. Their privilege is that they are authorized by their country's regulatory agency to return an aircraft to service and their responsibility is that they are expected to uphold the legal expectations of safety. In this sense, they become the marshals of airworthiness of an aircraft. As professionals, they are expected to have the adequate level of technical knowledge and the ability to apply that knowledge to be the marshals of airworthiness. Once employed to exercise the privileges of their authority, these maintenance professionals are subjected to various influences of organizational as well as national, which in turn, tend to affect the practice of their responsibility. For example, they learn about the organizational norms (sometimes, bad norms such as using belt-loaders as stands while working on aircraft or pushing back an aircraft without the use of wing-walkers). Thus, throughout their career in aviation maintenance, the maintenance staff receives cultural training as well as technical training. The technical training is through formal classroom and on-the-job training sessions wherein they learn how to perform certain maintenance action.

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The cultural training is much more subtle and it tends to take place by the virtue of being immersed in the environment new professionals observe what their peers do and do not do; they observe what the management's expectations are regarding technical as well as safety issues; and they observe the effects of non-compliance with management's expectations. Overall, through such immersion in the maintenance environment, they acquire technical as well as cultural knowledge that enables them to better align themselves with their peers. In this sense, we are saying that the type of professionalism developed by an individual is highly dependent on the organizational and national cultures surrounding that individual. Now, the question is, 'Does an organization shape an individual or does an individual shape an organization'?'. We would answer this question as, 'It depends!' We believe that each individual should have a certain threshold of professionalism. It is that individual's responsibility to raise the individual professionalism of his/her subordinates-in this sense, the individual is shaping the organization by shaping the people within his/her span of control. If the organization's expectations are higher than the individual's threshold, the individual should improve his/her practices to meet the organization's expectations. The organization, on the other hand, should have (a) structured on-the-job training to help the individuals improve themselves and (b) a periodic evaluation system to assess the individual's performance. If the organization's expectations are lower than the individual's threshold, the individual has three choices: acquiesce to the organization's expectations, seek proper channels to improve the organization, or leave the organization. We define professionalism as follows: Professionalism is the ability to refuse to take Blatant Risks and persistence to minimize Stymie Risk, Normalized Risk, and Good Samaritan Risk. Therefore, professionalism is a work in progress, a journey not a destination! We present six elements of professionalism that are specifically applicable to the aviation maintenance environment. These six elements can be ed using the acronym CAPWIT: Communication, Assertiveness, Preparation, Work Management, Integrity, and Teamwork. 9.9.1 KEEPING UP-TO-DATE, CURRENCY As discussed earlier, aircraft maintenance engineers undertake an approved course to obtain the knowledge and basic skills to enter the profession. This training is followed by instruction in more specific areas, such as maintenance of individual aircraft and specific systems. However, the aviation industry is dynamic: operators change their aircraft, new aircraft types and variants are introduced, new aircraft maintenance practices are introduced. As a consequence, the engineer needs to keep his knowledge and skills up-todate.

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To maintain his currency, he must keep abreast of pertinent information relating to: new aircraft types or variants new technologies and new aircraft systems new tools and maintenance practices modifications to current aircraft and systems he works on revised maintenance procedures and practices Engineers are likely to keep up-to-date by: undertaking update courses reading briefing material, memos and bulletins studying maintenance manual amendments Responsibility for maintaining currency lies with both the individual engineer and the maintenance organization for which he works. The engineer should make it his business to keep up-to-date with changes in his profession (ing that making assumptions can be dangerous). The organization should provide the appropriate training and allow their staff time to undertake the training before working on a new aircraft type or variant. It should also make written information easily accessible to engineers and encourage them to read it. It is, of course, vital that those producing the information make it easy for engineers to understand (i.e. avoid ambiguity). Anecdotal evidence describes a case where a certain maintenance procedure was “proscribed” (i.e. prohibited) in a service bulletin. The technician reading this concluded that the procedure was “prescribed” (i.e. defined, laid down) and proceeded to perform the forbidden action. From a human factors point of view, small changes to the technology or procedures concerning existing aircraft carry potentially the greatest risk. These do not usually warrant formal training and may merely be minor changes to the maintenance manual. Although there should be mechanisms in place to record all such changes, this presumes that the engineer will consult the updates. It is part of the engineer’s individual responsibility to maintain his currency.

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9.9.2 ERROR PROVOKING BEHAVIOUR As technology advances and systems become more complex, we sometimes forget that even the most sophisticated processes still rely on human judgment and skills, whether in medicine, transport, manufacturing or other industries. We can redesign tools, select better materials and develop better processes. But we cannot design better people. Whether we like it or not, we are stuck with the original 'Mark I' human being to maintain our complex systems. And an unchangeable part of the human condition is fallibility. Although, as indicated earlier, many maintenance incidents reflect system problems, the maintenance staff themselves are the last line of defence in that system. Most workers have little control over system issues such as hours of work, equipment and work schedules, but there are things that individuals can do to reduce their chances of being involved in an incident. Most importantly, our skills, habits, beliefs and knowledge can all be changed in ways that increase the reliability of human performance. PERSON MEASURES UNDERSTANDING ERROR-PROVOKING FACTORS The first step for maintenance personnel is to obtain some basic knowledge about human performance. Maintenance staff needs to know about the limitations of their shortterm memory, how fatigue affects performance, and a host of other facts about human strengths and weaknesses. For this reason, human factors training for maintenance personnel are now required by the International Civil Aviation Organization (ICAO) and the European Aviation Safety Agency (EASA). Once maintainers are aware of their own vulnerabilities, they can lean to recognize human performance danger signs. The ability to appreciate the significance of these 'red flags' is self-protecting skill worth developing. Below are listed some of the most potent error-provoking factors in maintenance activities. EXCESSIVE RELIANCE ON MEMORY Our memories are not always as reliable as we think particularly when we are tired. Memory lapses are the most common errors in maintenance. It is tempting fate to interrupt a part-completed job without adequate reminders to tell you, and others, of its stage of progress. You run the risk of a memory lapse every time you try to keep a critical task step in mind to perform later without any reminders. It is better to assume that you will forget, and take precautions, than to hope that you will .

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INTERRUPTIONS Maintenance activities are subject to frequent interruptions-someone needs advice, there is a phone call, or an urgent job needs to be finished off elsewhere. Whatever their nature, however, all such interruptions act to raise your stress level and increase the likelihood of a memory lapse. The most likely error is an omission. It is very important that you are aware of these risks and take steps to combat them. An obvious counter-measure is to anticipate the 'now where was I?' question when you take up the task again, and to leave behind a clear reminder of exactly where you had to stop. PRESSURE Signs of pressure come in many forms. Being asked repeatedly 'How long is it going to take?' Getting angry during a job.Starting to curse more than usual.Being anxious to go home as soon as you complete the job. Under such pressures, even the most careful workers can find themselves leaving out steps or taking shortcuts. Be aware of these pressures and ensure that they do not lead to risk-taking or cutting corners. TIREDNESS You may not feel tired, but if you have not had a good night-time sleep in the last 24 hours, or you have been at work for longer than 12 hours there is a good chance that you will be impaired by fatigue. Fatigue can increase your chances of making errors, particularly memory lapses. Sleepy people are also more irritable and harder to work with. INADEQUATE COORDINATION BETWEEN MAINTENANCE STAFF A breakdown in coordination is one of the most common circumstances leading to incidents. In many cases, coordination breaks down when people make unspoken assumptions about a job, without actually communicating with each other to confirm the situation. Sometimes maintenance staff fear that they will give offence if they are seen to check the work of colleagues too thoroughly or ask too many questions. Coordination danger signs include rushed shift handovers, a lack of adequate communication, not asking questions because you feel silly or do not want to offend a work colleague, and working with unfamiliar people. UNFAMILIAR JOBS If you are performing a task that is not part of your normal duties, even if you used to perform it in previous years, you are entering a danger zone for error. If an unfamiliar maintenance task is being performed on the basis of 'trial and error', you must recognize that your chances of getting it wrong are greatly increased. A further point to note is that a significant number of aviation maintenance incidents have involved supervisors helping out by getting involved in hands-on work. Although such people may be technically qualified to perform the work, and indeed highly motivated to do a proper job, their practical skills may be degraded.

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AMBIGUITY Any situation in which you are unsure of what is going on should be a sign to call a halt and clarify the task. Such situations are particularly common in team-based work environments, where 'diffusion of responsibility' can result in people assuming that someone else knows what is going on and has taken charge. HIGHLY ROUTINE PROCEDURES Any procedure that you can perform 'with your eyes closed', such as opening and closing -access covers or checking oil levels, is a danger zone for slips and lapses. Because we are so familiar with such tasks, our attention may wander elsewhere, leaving our actions largely under the control of the 'mental autopilot'. While we cannot stop such tasks from being 'on automatic', we can remain vigilant and spot the errors that will occur from time to time. UNDERSTANDING WHY PEOPLE VIOLATE GOOD PROCEDURES Unlike mistakes or lapses, violations are - for the most part - deliberate actions. People choose to deviate from safe operating procedures, rules and accepted codes of practice. This intentional element makes them far more amenable to management at the individual and team levels. Changing the underlying attitudes and beliefs is often a slow business, but it can be done. Intentions to violate are shaped by three interrelated factors:Attitudes to behaviour ('I can do it.') - These are the beliefs a person has regarding the consequences of some behaviour. How do the perceived advantages of violating balance out against the possible risks and penalties? Subjective norms (they would/would not like me doing this.') - These are the views that some important reference group (relatives, colleagues, friends and so on) might hold about your behaviour. Will they approve or disapprove, and how much does the person want to be ired or respected by these 'close others"? Perceived behavioural control ('I can't help it.') - How much control does the person feel that he or she exercises over the violating behaviour? This factor is likely to be of considerable importance in fatalistic cultures, particularly in regard to judgements about the consequences of violations. It will also come into play when the individual observes that although local management may pay lip service to the regulations, they actually condone violations, particularly where non-compliance means getting an urgent job done on time. Where the local climate neither rewards compliance nor sanctions violations, the individual is likely to feel that he or she has little control over the situation and can best fit in by doing what everyone else does.

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MEASURES DESIGNED TO REDUCE VIOLATIONS The most commonly used technique for reducing violations is aimed at the first of the three elements above, attitudes to behaviour. Efforts are made to scare people into compliance by graphic posters and videos that highlight the grisly consequences of unsafe behaviour These fear appeals can serve three useful functions. First, they inform people about the links between unsafe acts and safety. Second, they have the power to shock. Third, they should indicate the correct way of doing things. However, fear appeals, by themselves, tend to have only limited impact. The main problem is that those most likely to violate-young men-tend to be immunized against such appeals by their unrealistic optimism. Social controls address the second factor listed above: subjective norms. That is, the extent to which other people - whose opinions matter to the individual - would approve or disapprove of the violating behaviour. The evidence to date is that social controls represent one of the most effective ways of modifying individual behaviour. We are social animals. We need the approval, liking and respect of those we care about. If we become convinced that these 'significant others' will strongly disapprove of our planned actions, we are likely to think twice before carrying out this behaviour. This does not mean that we will never violate, but it is likely to give us pause. Many of the manageable ways of influencing social controls 'involve group discussions and group activities. 9.9.3 ASSERTIVENESS Speak-up when you do not know how to do a particular job, you think that one of your team- is doing it incorrectly, or when you discover your own or systemic errors. Assertiveness includes reporting the problem to Quality Assurance. Assertiveness involves verbal alerting of a discrepancy as well as constructive analysis of one's own judgment. In essence, we are talking about assertiveness toward others as well as assertiveness toward oneself. When the inner voice tries to raise concerns, it is time to consider that concern that is assertiveness toward oneself. Assertiveness is not only 'speaking-up', but also attending to others when they are speakingup. Typically, inspectors and Maintenance Engineers are very good at speaking-up because their professional responsibility is to identify discrepancies. Technicians tend to not speak-up because they either do not know that they have committed an error or they are afraid of the consequences of disclosing their error.

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MODULE 9

HUMAN FACTORS

SUB MODULE 9.10

ORGANIZATION’S HUMAN FACTOR PROGRAM

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Page No ii






CONTENTS 9.10 ORGANIZATION’S HUMAN FACTOR PROGRAM ............................

10-1

QUALITY POLICY ................................................................................

10-1

Human factors training procedure [MOE extract]............................

10-2

9.10.1 Reporting errors .........................................................................

10-3

9.10.2 Disciplinary policy ......................................................................

10-11

DISCIPLINARY PROCEDURE - LICENCED AIRCRAFT ENGINEERS/APPROVAL HOLDERS10-11 .......................................................................................................... DISCIPLINARY PROCEDURE -TECHNICIANS .......................................

10-13

9.10.3 Error investigation .....................................................................

10-14

9.10.4 Action to address problems .......................................................

10-15

9.10.5 ....................................................................................

10-15

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9.10 ORGANIZATION’S HUMAN FACTOR PROGRAM EASA part 145.A.30 (e) state that: The organization shall establish and control the competence of personnel involved in any maintenance, management and/or quality audits in accordance with a procedure and to a standard agreed by the competent authority. In addition to the necessary expertise related to the job function, competence must include an understanding of the application of human factors and human performance issues appropriate to that person's function in the organization. ‘Human factors’ means principles which apply to aeronautical design, certification, training, operations and maintenance and which seek safe interface between the human and other system components by proper consideration of human performance. ‘Human performance’ means human capabilities and limitations which have an impact on the safety and efficiency of aeronautical operations. QUALITY POLICY We at SriLankan Airlines - Engineering & Maintenance division are committed to provide a service par excellence that would continually delight our customers where safety of the aircraft, reliability of our service and punctuality will be our key goals To achieve this objective we shall: Recognize safety as a prime consideration in all our activities Ensure human factor requirements are identified and applied to eliminate errors and that all employees fully comply to procedures, safety standards and regulations. Ensure an effective system of communication is established to report and review maintenance related errors and incidents. Ensure all internal operations are carried out under controlled conditions and in an audited environment Ensure that all customer/ regulator requirements are continually determined with the view of meeting with those requirement Ensure all aircrafts are routinely monitored and maintained and thereby made commercially available to maximize revenue generation. To this end, we are committed to establish and maintain a Quality Management System and set quality objectives at all relevant levels of the division and review these objectives at planned intervals for continual improvement. 1st'September 2005

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Chief Technical Officer





HUMAN FACTORS TRAINING PROCEDURE [MOE EXTRACT] Objective: The objective of this procedure is ensure the Organization is concerned to optimize the relationship between human resource and their activities, by systematic application of human sciences, integrated within the framework of systems engineering and clear processes and procedures under proper consideration of human performance. GENERAL:  The human factors training program is implemented to reduce maintenance errors and provide means of guidance for certifying staff.  It is also envisaged that human factors training will raise the awareness of the important topic to assist in improving the understanding of how human capabilities and limitations can influence task performance and safety in the working environment.  All appropriate personnel engaged in the Aircraft Engineering and maintenance shall attend initial & continuation human factors training. This includes managers, maintenance staff & ing staff.  The initial human factors training for maintenance staff should be based on the Technical Training Manual. Quality Assurance will ensure all required staff as per EASA Part 145 has been through human factors training accordingly.  SriLankan airlines Quality Assurance departments will ensure all staff required to obtain human factors training receives continuation training at least once in every two years. Note. Training records are maintained to reflect compliance.  Each department will prepare a job description for each job profile in its department, clearly identifying the duties and responsibilities with the necessary competence required to carry out the job. The Job Description will be retained by the individual sectional managers for engineering and maintenance department personnel or may be obtained from HR division. Responsibility: The sectional managers are responsible for defining & documenting training objectives, stipulating training programs and internal & external coordination of such programs, with regard to qualification requirements. These may be implemented through the SriLankan Technical Training Manager.

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9.10.1 REPORTING ERRORS REPORTING OF DEFECTS TO THE QUALITY ASSURANCE Objective: The purpose of this procedure to ensure that General Procedure: The DGCA airworthiness requirement, applicable to aircraft ed in Sri Lanka, requires that a company which manufactures overhauls or repair aircraft or any part or equipment fitted to such aircraft, or any person who certifies certificate of Release to Service for an aircraft or any part or any equipment shall report to the DGCA, Sri Lanka any incident defect or malfunction which endangers or, if not corrected, would endanger the aircraft, its occupants or any other person.

REPORTING OF DEFECTS TO REGULATORY AUTHORITY, OPERATOR & MANUFACTURER Objective: The purpose of this procedure is to describe the system and responsibilities when reporting any condition of the aircraft or aircraft component that could seriously hazard the aircraft. GENERAL PROCEDURE:  It is found necessary that certain occurrences affecting or which could affect air safety shall be reported to the Regulatory Authority.  The primary objective of the mandatory reporting scheme is to improve the level of airworthiness. These occurrences are in turn investigated and where necessary, the implementation of corrective action is recommended.  The Quality Assurance Section undertakes the istration and control of the system with the overall responsibility vested in the Manager Quality Assurance.

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REPORTING OF UN-AIRWORTHY CONDITIONS 

A condition that could seriously hazard the aircraft is normally limited to;

 Serious cracks, permanent deformation, burning, serious corrosion of the structure found during scheduled maintenance of aircraft/engine systems.  Failure of any emergency system during scheduled testing. Reporting methods  Aircraft incident/accident Report (AIAR 1)  Occurrence report Aircraft Incident/Accident Report (AIAR 1) Reporting of Occurrences while the aircraft is in flight or on ground under the control of the flight crew. The commander of an aircraft is responsible for the safety of the aircraft and those on board from the time the aircraft moves or is capable of doing so under its own power and until such time the aircraft is parked and all engines shut down.  An aircraft incident/accident report is classified as a Mandatory Occurrence Report (MOR) and is generated by the flight crew.  Aircraft incident/accident reports are to be notified to the Authority within 12 hours of the occurrence through the Flight Operations Department.  The Quality Assurance section investigates those reports that have an Engineering involvement. Reports of a purely operational nature are processed by the Flight Operations Department.  All reports which need an engineering input are sent to the 'Manager Quality Assurance by the Flight Safety Manager.  Full details of the closed report are directed to the Regulatory Authority.

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Occurrence Report From the foregoing paragraph above, whenever an Aircraft is on ground and is not under the control of the commander any incident during this time frame is the responsibility of the Certifying Staff. (e.g. during push back) Upon receipt of an above report, Quality Assurance will allocate a reference number from the report .  The occurrence report may be raised for a mandatory or non-mandatory finding/observation. The originator should classify the report as such if in his opinion, the occurrence warrants such action. In this case, Quality Assurance section will advise the airworthiness authority.  All occurrences shall be notified to the Quality Assurance section on an Occurrence Report Form.  Completed Forms accompanied by any relevant documentation and where possible photographs, must be forwarded by the most expeditious method but in any case within 72 hours of occurrence. Maintenance Responsibilities  In the case of an aircraft Incident/Accident Report, the Aircraft Commander shall advise the Duty/Handling Engineer of the existence. Additionally, for technical reports, the aircraft's Technical log shall be endorsed to that effect and details entered in the appropriate section.  The Certifying Staff -in-charge of the aircraft will be responsible for performing any rectification work and making the necessary certification in the technical log.  Notification of Incidents/Accidents or Occurrences arising at outstations will be signaled without delay to the MQA by telex, CMBEIUL and copied to CMBELUL and CMBEZUL.  Parts and Components that are the subject of an Aircraft Incident/Accident or Occurrence Report will be handled as detailed below.  The investigation and processing of the reports are described in Para below.

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REPORTABLE OCCURRENCES A reportable Occurrence is an incident, malfunction or defect on an aircraft or its equipment, which warrants investigation other than, is normally carried out during troubleshooting and/or rectification. The following example of occurrences which would qualify for reportable occurrence action are included to assist reporting staff in making the necessary judgments. It is not a complete listing of all Reportable occurrences.  Any failure of aircraft primary structure.  Damage from whatever cause, which necessitate repair or rectification before further flight. E.g. ground collision, fluid spillage.  Cracks, permanent deformation or corrosion not previously experienced or greater than previously encountered.  Any failures of non-primary structure, which endangers or could, endanger an aircraft or its occupants.  Fire or explosion.  Inability to shut down an engine or control thrust.  Malfunction of a thrust reversal system in-flight.  Fuel supply and distribution system malfunctions.  Significant leakage of fuel, oil or hydraulic fluid.  Malfunction of any control, including stiffness in operation, movement limitation or delayed response.  Significant failure or malfunction of an electrical, hydraulic pneumatic, oxygen or ice-protection system.  Significant failure or malfunction of a communication or navigation system.  Significant failure of wheels, lyres or brakes.  Defects of a repetitive nature, which, if treated in isolation would not necessarily require reporting action.  Components and parts found to be unserviceable on withdrawal from stores.  Components and parts found to be maladjusted, incorrectly assembled or showing evidence of a poor or incorrect maintenance practices.  Components and parts fitted as serviceable units to an aircraft, which are found to be defective during post-installation testing/operation.  Erroneous information in Approved Technical Publications.

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HANDLING OF REMOVED COMPONENTS SUBJECT TO AN INCIDENT/ACCIDENT/OCCURRENCE  Where practical, small or manageable defective or suspect parts must accompany the associated report with an unserviceable Label attached to the component.  Parts and associated documents dispatched to Colombo from line stations by hand of crew, OCS mail or in the hold of an aircraft shall be listed in the signal referred to in the Para 3.8.2. If this is not possible, dispatch details must be signaled as soon as possible.  All parts and components must be identified with an Unserviceable Label and an Incident Label.  The incident Label must be endorsed to the effect that the component or part is the subject of an Incident/Accident Report or an Occurrence Report.  All parts that are subject of an investigation are to be routed to Engineering Materials section, Issue counter. ENGINEERING MATERIALS ACTION  Any item too large to accompany its associated report will be routed to Engineering Materials section, Issue Counter with an unserviceable Label, where it will be held on an "Occurrence Report rack'. It is important that defective parts are not disturbed in any way and that adequate protection is afforded to preclude damage.  For parts that are air-freighted to Colombo, the dispatching Station Engineer/Agent will signal all relevant details, including date, flight and AWB numbers to MQTCMBEIUL and copied to CMBELUL, CMBEZUL and CMBESUL  On receipt of such items a suitable entry will be made in a component receipt .  No item on the Occurrence Report rack may be disturbed in any way (e.g. cannibalization of sub-assemblies) without the prior permission of Quality Assurance Manager or Manger Quality Assurance.  The issue counter will immediately inform the Quality Assurance section of the receipt of such items.  All such parts and components will be held in quarantine pending disposal instructions from the Quality Assurance.

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INVESTIGATION PROCEDURE  Investigative action into both Aircraft Incident/Accident Report and Occurrence Reports are initiated by the Manager Quality Assurance, who will determine whether Quality Assurance or an external Engineering Organization will be responsible for the investigation.  Technically related aircraft Incident/Accident Reports and Occurrence Reports will, depending upon their nature, be directed to a Quality Assurance Inspector (QAI) or the investigating Engineering Organization through the Quality Assurance Manager (QAM).  In the case of internal investigations, QAM will assign a specialist investigator (a QAI) and ensure that the report is processed expeditiously.  In the case of investigations carried out by an external organization, the MOA will delegate the responsibility of coordinating the investigation to QAM or a QAI,  Investigations will be conducted in a manner that ensures a timely and satisfactory conclusion, including where necessary, liaison with other Departments and outside sources. Investigators are responsible for collecting all information and data and the retention of all ing documents including, where necessary, evidence of preventive action taken.  The investigator is responsible for inspecting any parts and components under quarantine, and subject to the satisfactory progress of the investigation, authorizing the release of such parts and components to the appropriate overhaul or repair organization.  If a component strip report is required in order to further an investigation, the investigator should immediately advise the Component Control Engineer of the Engineering Materials Section of this requirement. The Component Control Engineer will forward the request immediately to the relevant overhaul or repair organization. INCIDENTS AT A CONTRACTING ORGANIZATION  Should an Incident arise on anSriLankan Airlines aircraft undergoing maintenance at a contracted organization, then that organization is responsible for investigating the occurrence.  The organization will promptly advise SriLankan Airlines of the occurrence and conduct an investigation utilizing its own system.  The MQA will delegate a suitable member of the QA staff to liaise with the organization. When necessary, SriLankan Airlines will obtain the services of an independent organization to conduct such investigations. Any damage part or component will be the property of SriLankan Airlines and will be sent to SriLankan Airlines in the condition in which they were at the time of the incident.

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This requirement will be included in any contractual agreement with a maintenance organization.  A copy of the completed investigation report will be forwarded to the SriLankan Airlines Manager Quality Assurance. ITEM DISPOSAL ON COMPLETION OF INVESTIGATIONS  All defective parts and components shall be retained until an investigation is fully completed.  Rotable and repairable items will be routed to the appropriate workshop or overhaul agency.  Consumable and non-repairable items, which can serve no useful purpose in any other application, may be released for scrap.  In all cases items may not be disposed of without the prior consent of the Manager Quality Assurance.  Manager Quality Assurance may advise Engineering Materials Issue counter of the course of action required. CLOSURE OF REPORTS  The completed QAI Investigation Report together with all ing documents will be returned to Manager Quality Assurance through QAM.  As applicable, Quality Assurance Manager would forward completed Aircraft Incident/Accident Report to Director General of Civil Aviation.  All closed reports, including copies of closed Aircraft Incident/Accident Report will be retained on file by the Quality Assurance Department. GENERAL RESPONSIBILITIES  It is the responsibility of the Technical crew and Certifying Staff who become aware of a reportable occurrence to submit a report in accordance with the requirement of this instruction.  The Quality Assurance Manager is responsible in notifying the CAA SL or the operators' airworthiness authority within the stipulated period.  The Engineering Materials Manager is responsible in ensuring that the removed incident components are placed on the 'Occurrence Report Rack' and such items are reported to QAM. Unauthorized removal of these items will be prohibited.  The nominated Quality Assurance Inspector/Engineer (QAI/QAE) is responsible in collecting necessary details for the investigation, analyzing the event and

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submitting a report to MQA/QAM for onward transmission to the CAA SL or other operator/authority as applicable. PROCEDURES FOR NOTIFICATION OF MAINTENANCE DATA INACCURACIES TO THE TYPE CERTIFICATE HOLDER Objective: The objective of this procedure is to ensure all inaccuracies of maintenance data is notified to the type certificate holder. GENERAL DESCRIPTION:  If any maintenance inaccuracies or ambiguities are identified, the relevant Engineer/technician would a raise an occurrence report (ENG/QAIGN/022) in accordance with the occurrence reporting procedure.  Quality assurance would evaluate the occurrence reports and reports pertaining to the above will be forwarded to the relevant Technical services group. Quality assurance is responsible for keeping a record of such reports to ensure proper corrective action on the same.  Relevant technical services group should liaise with the manufacturer to bring to attention of the inaccuracy/ambiguity of maintenance data.  Tech services group should issue temporary revision of the relevant manuals after receipt of instructions clarifying the inaccuracy/ambiguity from the manufacturer.  Tech services group should review the manuals for required revision at the next revision cycle.  Quality assurance may close the record once the manuals are effectively revised. RESPONSIBILITY:  The Manager Quality Assurance will advise the responsible author of the maintenance data in order to notify about the deficiency and request intended corrective action. MQA is also responsible to hold such records.  Manager Technical Services is responsible for liaising with the relevant manufacturer in order to clarify the inaccuracy/ambiguity and to raise necessary internal paperwork to rectify/correct the situation until the manuals are revised.

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9.10.2 DISCIPLINARY POLICY DISCIPLINARY PROCEDURE - LICENCED AIRCRAFT ENGINEERS/APPROVAL HOLDERS Objective: The purpose of this procedure is to describe the disciplinary procedure and deterrent measures to be taken by QA for Certifying Staff. GENERAL PROCEDURE  The intention is to improve the overall quality standard of aircraft maintenance and to instil a greater degree of discipline and responsibility in Certifying Staff in keeping with the ultimate goal of Total Quality Management. UNSATISFACTORY PERFORMANCE CATEGORIES The following categorization of unsatisfactory performance of duties by Certifying Staff is considered.  Category A ACTION THAT NEITHER COMPROMISE THE SAFETY OF THE AIRCRAFT NOR THE ENGERS AND CREW NOR RESULT IN UNWARRANTED DELAYS IN THE FLIGHT SCHEDULE. 7. Failure to properly document maintenance work, which has been certified. 8. Failure to adhere to requisite procedures for the handling of components such as those for cannibalization, receiving, transporting and returning components to the stores, no damage however being caused to the components. 9. Failure to clear components from the "Retain on Shelf' (ROS) racks in stores within a period of 14 days from the date of return of the component to stores.  Category B NEGLIGENT CONDUCT WHICH, WHILE NOT COMPROMISING THE SAFETY OF THE AIRCRAFT AND THOSE ON BOARD, COULD RESULT IN FINANCIAL LOSS TO THE COMPANY. 1. Damage caused to components while in the custody of the Certifying Staff. 2. Loss or damage to tools/test equipment while in the custody of or while being used under the instruction or supervision of the Certifying Staff.

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 Category C ACTIONS THAT WOULD COMPROMISE THE CONDITIONS OF ISSUE OF THE CERTIFICATE OF AIRWORTHINESS OF THE AIRCRFT, BUT DO NOT IN THEMSELVES ENDANGER THE AIRCRAFT OR ITS OCCUPANTS. 1. Failure to certify maintenance work carried out. 2. Failure to carry out all scheduled maintenance work called for by the Approved Maintenance Schedule without authorization granted by the Quality Assurance Manager to carry forward such maintenance. 3. Deferment of defects without MEL authority. 4. Fitment of components outside the authority of the manufacturer's Illustrated Parts Catalogue or that granted by the Quality Assurance Manager or his designated representative. 5. Performance of work outside the scope of the Certifying Staff.  Category D ACTIONS, WHICH COULD COMPROMISE THE SAFETY OF THE AIRCRAFT OR OF THOSE ON BOARD. 1. Negligence on the part of the Certifying Staff resulting in the malfunction of aircraft system/components. 2. Performance of unauthorized repairs on the aircraft or its components. 3. Failure to observe safety precautions during maintenance. ASSIGNMENT OF CATEGORIES The category for each deficiency will be assigned by the QAM who will review the category assigned prior to initiating disciplinary action. The decision of the QAM will be final. No appeals will be entertained. It is expected that the Certifying Staff would have presented all mitigating circumstances at the time of submission of explanation.

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DISCIPLINARY PROCEDURE -TECHNICIANS Objective: The purpose of this procedure is to describe the disciplinary procedure and deterrent measures applicable to Technicians involved in aircraft maintenance and workshop areas. GENERAL PROCEDURE  In the absence of a defined policy on classification of maintenance work related deficiencies attributable to technicians and the resultant QA follow-up requirements warranted by the detection of such failure, the following disciplinary procedure is applicable to technicians.  The intention is to further improve the overall quality standard of aircraft Maintenance and to instill a greater degree of discipline and responsibility in technicians in keeping with the ultimate goal of total quality management. CATEGORIES OF PERFORMANCE DEFICIENCIES  Category – A ACTIONS THAT NEITHER COMPROMISES THE SAFETY OF THE AIRCRAFT NOR OF THE ENGERS AND CREW NOR RESULT IN UN-WARRANTED DELAYS IN THE FLIGHT SCHEDULES. Failure to document and/or to sign in the technician’s column for maintenance work carried out. If more than one technician is assigned and involved in the work, then this responsibility will lie with the most senior technician (by staff number) assigned to the specific task and/or to the technician who had a major role in carrying out the task.  Category- B NEGLIGENT CONDUCT WHICH, WHILE NOT COMPROMISING THE SAFETY OF THE AIRCRAFT AND THOSE ON BOARD COULD RESULT IN FINANCIAL LOSS TO THE COMPANY.  Damage caused to components while in the custody of the technician.  Loss or damage to tools/consumable/test equipment while in the custody of or while being used by a technician.  Actions resulting in damage to the aircraft or its components in the presence of the technician where it may reasonably be proved that it was within his power to prevent such actions.

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 Any other action that is considered as negligent conduct which results in the technical loss to the company.

 Category – C ACTIONS THAT COULD COMPROMISE THE SAFETY OF THE AIRCRAFT OR OF THOSE ON BOARD  Negligence on the part of the technician resulting in the malfunction of an aircraft system/components.  Performance of any unauthorized work on the aircraft or its components or work without the concurrence of the certifying engineer.  Failure to observe safety precautions during maintenance. ASSIGNMENT OF CATEGORIES The category for each deficiency will be assigned by the QAM who will review the category assigned prior to initiating disciplinary action. The decision of the QAM will be final. No appeals will be entertained. It is expected that the technician would have presented all mitigating circumstances at the time of submission of explanation. 9.10.3 ERROR INVESTIGATION PROCEDURES TO DETECT AND RECTIFY MAINTENANCE ERRORS Objective: The objective of this procedure is to ensure any defect or error detected during, after or due to maintenance work performance will be corrected in accordance with the stipulated procedures. GENERAL DESCRIPTION  Certifying staff are responsible for ensuring that any maintenance task performed by them or under their supervision is in accordance with approved procedures.  In stringent cases where only one person is available to carry out same tasks, then the work card/ worksheet should include an additional stage for reinspection of the work by the person after completion of all of the same tasks.  Where abnormalities are encountered during implementation of maintenance tasks, it is the responsibility of the Engineer to raise a report and direct it to Manager Quality Assurance as soon as possible.

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 The detailed procedure for the detection & rectification of maintenance errors found during base & line maintenance is defined in the EPM 02-11-06, 'Occurrence Reporting". Responsibility: Errors captured by the occurrence reporting system are monitored and controlled by Manager Quality Assurance in order to prevent a recurrence. 9.10.4 ACTION TO ADDRESS PROBLEMS Actions required to address problems can be divided in to two: addressing local factors and addressing organizational factors. Exactly what local factors are addressed depends upon the workplace. Some factors will be common to all locations, but others will vary from place to place. Find below some of the local factors you will find in our work areas.  Knowledge, skills and experience  Morale  Tools, equipment and spare parts  Technical  Fatigue  Pressure  Lack of general equipment such as computers, printers etc  Paperwork, manuals and procedures  Personnel safety features Periodic reviews, group discussions, focused group meetings could reveal actual problems and participation of staff in continuous improvement schemes, Kaizen programs will no doubt will enhance the work environment to have better safety. 9.10.5 should be given to the workforce and to original reportees concerning actions, to encourage continued future reporting. A magazine can be an effective way of providing to the workforce in general, although care needs to be taken not to breach confidentiality and to dis-identify occurrences. The most effective is that which shows that something has been changed for the better as the result of an occurrence report or investigation.

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Some times quality Notices (QN) are issued based on findings of occurrence reports and investigation reports. Management is given of audit findings in the form of audit finding reported. Annual meeting with able Manager provide platform to discuss current issues and discuss potential solutions to improve safety and prevent errors and occurrences.

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