ET0437 Human Factors and Quality Systems PDF

ET0437 Human Factors and Quality Systems Chapter 1 – Introduction to Human Factors and Communication ET0437 - Chapter 1 1 1‐1 Introduction to Human Factors Topics The need to take human factors into account. Incidents attributable to human factors / human erro...

ET0437 Human Factors and Quality Systems Chapter 1 – Introduction to Human Factors and Communication ET0437 - Chapter 1 1 1‐1 Introduction to Human Factors Topics The need to take human factors into account. Incidents attributable to human factors / human error Murphy’s law. ET0437 - Chapter 1 2 The Need To Take Human Factors Into Account 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 ◦ The role of the people associated with aircraft became an area of focus. ◦ Pilots were supported initially with mechanisms to help them stabilise 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 was born. ET0437 - Chapter 1 3 The Need To Take Human Factors Into Account CIVIL AIRCRAFT ACCIDENTS In 1940 ◦ It was calculated that approximately 70% of all aircraft accidents were attributable to man’s performance, that is to say human error. Other Causes 30% 35 years later ◦ When the International Air Transport Human Failure Association (IATA) reviewed the situation Flight Crew, ◦ They found that there had been no reduction ATC, in the human error component of accident Maintenance, Aircraft statistics. Design, etc. 70% ET0437 - Chapter 1 4 What is Human Factors? Human factors refers to the study of human capabilities and limitations in the workplace. Human factors researchers study system performance. ◦ 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 optimise the relationship between maintenance personnel and systems with a view to improving safety, efficiency and well-being. ET0437 - Chapter 1 5 What is Human Factors? Human factors include such attributes as: ◦ Human physiology ◦ Psychology (including perception, cognition, memory, social interaction, error, ◦ etc.) ◦ Work place design ◦ Environmental conditions ◦ Human-machine interface ◦ Anthropometrics (the scientific study of measurements of the human body) ET0437 - Chapter 1 6 The SHEL Model A model which is often used to aid in the understanding of human factors is the SHEL model Human factors concentrates on the interfaces between the human (the ‘L’ in the centre box) and the other elements of the SHEL model. Liveware – Liveware ◦ the interface between people and other people. S Liveware – Software H L L ◦ the interface between people and software. E Liveware – Hardware ◦ the interface between people and hardware. Liveware – Environment ◦ the interface between people and the environment. ET0437 - Chapter 1 7 The SHEL Model The elements of the SHEL model are: Software ◦ e.g. maintenance procedures, maintenance manuals, checklist layout Hardware ◦ e.g. tools, test equipment, the physical structure of aircraft, design of flight decks, positioning and operating sense of controls and instruments 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 Liveware ◦ (i.e. the person or people at the centre of the model, including maintenance engineers, supervisors, planners, managers ET0437 - Chapter 1 8 The SHEL Model S H L L Examples of the elements being deficient: E Software Environment ◦ Misinterpretation of procedures ◦ Uncomfortable workplace ◦ Badly written manuals ◦ Inadequate hangar space ◦ Poorly designed checklists, ◦ Extreme temperatures ◦ Untested or difficult to use computer ◦ Excessive noise software ◦ Poor lighting Hardware Liveware ◦ Not enough tools ◦ Relationships with other people ◦ Inappropriate equipment ◦ Shortage of manpower ◦ Poor aircraft design for ◦ Lack of supervision maintainability ◦ Lack of support from managers ET0437 - Chapter 1 9 The SHEL Model Despite the fact that modern aircraft are now designed to embody the latest self- test and diagnostic routines that modern computing power can provide, maintenance tasks are still being done by human beings. Liveware is at the centre of the model ◦ Software, Hardware and Environment must be designed or adapted to suit liveware ◦ Man has limitation. Software, Hardware and Environment) must be designed or adapted to assist his performance and respect his limitations. S H L L E ET0437 - Chapter 1 10  The SHEL Model With 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. ◦ We can work around that unreliability by providing good training, procedures, tools, duplicate inspections. ◦ 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. S H L L It is important to recognise human performance limitations in themselves and others, and to be able to avoid, detect E and rectify errors or error prone behaviour and practices ET0437 - Chapter 1 11 Incidents and Accidents Attributable To Human Factors / Human Error 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 Pilot deviated from basic operational procedures 33 Inadequate cross-check by second crew member 26 Design faults 13 Maintenance and inspection Maintenance and inspection deficiencies 12 deficiencies are one of the Absence of approach guidance 10 major contributory factors to accidents. 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 ET0437 - Chapter 1 12 Examples of Incidents and Accidents Accident to Boeing 737, (Aloha flight 243), Maui, Hawaii, April 28 1988 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 human-factors-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. ET0437 - Chapter 1 13 Examples of Incidents and Accidents Accident to BAC One-Eleven, G-BJRT (British Airways flight 5390), over Didcot, Oxfordshire on 10 June 1990 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 organisational and design factors. ET0437 - Chapter 1 14 Examples of Incidents and Accidents Incident involving Airbus A320, G-KMAM at London Gatwick Airport, on 26 August 1993 An incident in the UK in August 1993 involved an Airbus 320 which, during its first flight after a flap change, exhibited an undemanded 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. ET0437 - Chapter 1 15 Examples of Incidents and Accidents Incident involving Boeing 737, G-OBMM near Daventry, on 23 February 1995 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. ET0437 - Chapter 1 16 Common Observations 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 characterised 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. ET0437 - Chapter 1 17 Incidents and Accidents ‐ A Breakdown in Human Factors 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 recognise 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. ET0437 - Chapter 1 18 Incidents and Accidents ‐ A Breakdown in Human Factors All the examples 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. ET0437 - Chapter 1 19 Murphy’s Law 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 organisations of the need to look at human factors issues, recognise risks and to implement improvements. If everyone 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 show that errors can be made by experienced, well-respected individuals and accidents can occur in organisations previously thought to be “safe”. Murphy’s Law – If something can go wrong, it will. ET0437 - Chapter 1 20 1‐2 Communication Topics Within and between teams. Work logging and recording. Keeping up to date, currency. Dissemination of information. ET0437 - Chapter 1 21 Importance of 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. 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. ET0437 - Chapter 1 22 Communication Within and Between Teams Aircraft maintenance engineers often work as teams. Individuals within teams exchange information and need to receive instructions, guidance, etc. One team will have to pass 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. ET0437 - Chapter 1 23 Modes of Communication An aircraft maintenance engineer might regularly communicate: ◦ information ◦ ideas ◦ feelings ◦ Attitudes and beliefs As the sender of a message, he will typically expect some kind of response from 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 feedback. ET0437 - Chapter 1 24 Modes of Communication 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, handwritten 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. ET0437 - Chapter 1 25 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 channel of communication ◦ recognises and understands his language ◦ is able to make sense of the message’s meaning 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. ET0437 - Chapter 1 26 Verbal and Written Communication Language ◦ Ensure that the message coding used by the sender is appreciated by the recipient so that he can decode the message accurately. ◦ This means that engineers must have a similar knowledge of technical language, jargon and acronyms. Make sense of meaning ◦ The engineer has to understand the content of 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 ambiguity exists, the engineer must seek clarification. ET0437 - Chapter 1 27 Non‐verbal Communication Non-verbal communication ◦ A colleague may pass 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 can accompany verbal communication, example: a smile during a face-to-face chat. Non-verbal communication is also the predominant manner by which systems communicate their status. ◦ Example: Most displays in the aircraft cockpit present their information graphically. Body language can be very subtle, but often quite powerful. ◦ Example, the message “No” accompanied by a smile will be interpreted quite differently from the same word said whilst the sender scowls. ET0437 - Chapter 1 28 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). ◦ It is much less common for individuals within teams to use written communication. ET0437 - Chapter 1 29 Communication Within Teams 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. Good communication within a team helps to maintain group cohesion. 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 feedback to make sure your message has been heard and understood. ET0437 - Chapter 1 30 Communication Between Teams Communication between teams is critical in aircraft maintenance engineering. It is the means by which one team passes 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. ET0437 - Chapter 1 31 Communication Between Teams Communication between teams will involve passing on written reports of tasks from one shift supervisor to another. Ideally, this should be backed up by spoken details passed between supervisors and individual engineers. ◦ 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 minimise omissions. ET0437 - Chapter 1 32 Communication Problems There are two main ways in which communication can cause problems. Lack of communication Example: The engineer forgets to pass on pertinent information to a colleague, or a written message is mislaid. Poor communication Example: 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. ET0437 - Chapter 1 33 Communication Problems 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 terms 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. ◦ Problems with assumptions can be minimised if messages are unambiguous and proper feedback is given. Basic rules of thumb to minimise 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 ET0437 - Chapter 1 34 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. 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”. ET0437 - Chapter 1 35 Work Logging and Recording 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. The exact manner in which work should be logged tends to be prescribed by company procedures. ◦ It is usually recorded in written form. ◦ Symbols and pictures may 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’). ET0437 - Chapter 1 36 Work Logging and Recording The key aspects of work logging and recording are captured in the CAA’s Airworthiness Notice No. 3 (AWN3) “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.” ET0437 - Chapter 1 37 Work Logging and Recording Modern technology is also being implemented to improve the transfer of information in maintenance manuals to worksheets and workcards. ◦ 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. ET0437 - Chapter 1 38 Keeping Up‐to‐Date, Currency 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-to-date. ET0437 - Chapter 1 39 Keeping Up‐to‐Date, Currency 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 ET0437 - Chapter 1 40 Keeping Up‐to‐Date, Currency Responsibility ◦ Responsibility for maintaining currency lies with both the individual engineer and the maintenance organisation for which he works. ◦ The engineer should make it his business to keep up-to-date with changes in his profession (remembering that making assumptions can be dangerous). ◦ The organisation 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). ET0437 - Chapter 1 41 Keeping Up‐to‐Date, Currency Small changes to the technology or procedures ◦ 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. ET0437 - Chapter 1 42 Dissemination of Information Both the individual engineer and the organisation in which he works have a shared responsibility to keep abreast of new information. 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 organisation 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. It is imperative that engineers working remotely from the engineering base (e.g. on the line) familiarise themselves with new information (on notice boards, in maintenance manuals, etc.) on a regular basis. ET0437 - Chapter 1 43 Dissemination of Information 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 accountability system in place to enable supervisors to ensure that all mechanics had seen the applicable training and procedural information.” ET0437 - Chapter 1 44 Dissemination of Information Good dissemination of information within an organisation forms part of its safety culture. Communication is an active process whereby both the organisation and engineer have to play their part. ET0437 - Chapter 1 45