Module 9.1 General PDF

MODULE 9 HUMAN FACTORS Licence category A, B1, B2, B2L, and B3 9.1 General Module 9.1 General Certification statement and objectives These Study Notes comply with the syllabus of EASA Regulation (EU) No. 1321/2014 Annex III (Part-66) Appendix I, including the amendment Regulati...

MODULE 9 HUMAN FACTORS Licence category A, B1, B2, B2L, and B3 9.1 General Module 9.1 General Certification statement and objectives These Study Notes comply with the syllabus of EASA Regulation (EU) No. 1321/2014 Annex III (Part-66) Appendix I, including the amendment Regulation (EU) 2023/989, and the associated Knowledge Levels as specified below: Part-66 Knowledge Levels Objective Ref. A, B1, B2, B2L, B3 General 9.1 2 The need to take human factors into account; Incidents attributable to human factors/human error; Murphy’s law 1-2 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General Table of contents The need to take human factors into account ________ 4 The cost of maintenance error ____________________ 5 What is human factors? _________________________ 7 Unique human factors issues in aviation maintenance 9 Incidents and accidents attributable to human factors/human error ____________________________ 14 The statistics _________________________________ 14 Japan Airlines, Boeing 747, 1985 _________________ 16 Eastern Airlines, L-1011, 1983 ___________________ 18 Aloha Airlines, Boeing 737, 1988 _________________ 20 British Airways, BAC 1-11, 1990 _________________ 22 Air Midwest, Beech 1900D, 2003 _________________ 23 Excalibur Airways, Airbus A320, 1993 _____________ 26 British Midland, Boeing 737-400, 1995_____________ 26 The error chain ________________________________ 28 Murphy’s law _________________________________ 30 Origin ______________________________________ 30 Murphy’s law or sod’s law?______________________ 30 1-3 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General The need to take human factors into account Without the intervention of maintenance personnel, equipment Aircraft come with manuals that specify their performance used in complex technological systems such as aviation, rail envelopes and capabilities. Procedures, too, have been and marine transport, and medicine would drift towards a level created by people and can be documented and understood. of unreliability that would rapidly threaten efficiency and safety. But when it comes to people, we are faced with a system Despite the essential contribution of maintenance to system element with no operating manual and performance reliability, maintenance is also a major cause of system failure. specifications. It occasionally performs in ways not anticipated The rate of power station outages increases shortly after by the system designers. Some of these failures can be easily maintenance; maintenance quality is a major concern in the explained, an arithmetic error, for example, while others are chemical industry, and in aviation, there is evidence that harder to predict. maintenance contributes to an increasing proportion of accidents. As automated systems become increasingly Although individuals differ, researchers have discovered common, humans perform less direct manual control of general principles of human performance that can help us to equipment and systems. As a result, maintenance is becoming create safer and more efficient systems. The focus of this paper a major remaining point of direct interaction between people is on the functioning of people as elements of maintenance and technology, where human capabilities and limitations can systems in aviation. significantly impact system safety and reliability. Understanding the human factors in maintenance is more necessary than ever if we are to improve safety and reliability in aviation. Modern technological systems in manufacturing, transport and healthcare industries comprise equipment, procedures, and people. In most cases, we have a pretty good understanding of the performance characteristics of the engineered equipment that forms parts of these systems. 1-4 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General Accidents caused by human error, compared to machine causes, over time 1-5 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General The cost of maintenance error Since the end of World War II, human factors researchers have For example, in the case of a Boeing 747-400, a flight studied pilots and the tasks they perform, as well as air traffic cancellation can cost the airline around €140,000, while a delay control and cabin safety issues. Yet until recently, maintenance can cost an average of €17,000 per hour. In this context, it can personnel were overlooked by the human factors profession. be seen that even simple errors, such as gear pins left in place Whatever the reason for this, it is not because maintenance is requiring a return to the gate, can involve high costs. Even a insignificant. Maintenance is one of the most significant costs slight reduction in the frequency of maintenance-induced facing airlines. It has been estimated that 12 hours of schedule disruptions can result in significant savings. maintenance occur for every hour of flight. Most significantly, maintenance errors can have grave implications for flight safety. Accident statistics for the worldwide commercial jet transport industry show maintenance as the ‘primary causal factor’ in a relatively low 4% of hull loss accidents, compared with flight crew actions that are implicated as a primary causal factor in more than 60% of accidents. Yet primary cause statistics may tend to understate the significance of maintenance as a contributing factor in accidents. In 2003, Flight International reported that ‘technical/ maintenance failure’ emerged as the leading cause of airline accidents and fatalities, surpassing controlled flight into terrain, which had previously been the predominant cause of airline accidents. According to former NTSB Board member John Goglia, poor maintenance has been implicated in 7 of 14 recent airline accidents. Maintenance errors threaten flight safety and can impose high financial costs through delays, cancellations, diversions, and other schedule disruptions. 1-6 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General Causes of accidents and incidents in aviation 1-7 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General What is human factors? The aviation industry uses the term ‘human factors’ in many The term human factors in aviation maintenance engineering ways. are relatively new. Aircraft accidents such as that of the Aloha aircraft in the USA in 1988 and the BAC 1-11 windscreen The term is, perhaps, best known in the context of aircraft accident in the UK in June 1990 brought the need to address cockpit design and crew resource management (CRM). human factors issues in this environment into sharp focus. This However, those activities constitute only a tiny percentage of does not imply that human factors issues were not present aviation-related human factors, as it broadly concerns any before these dates nor that human error did not contribute to consideration of human involvement in aviation. other incidents; it merely took an accident to draw attention to human factors problems and potential solutions. Human factors refer 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. Human factors aim to optimise the relationship between maintenance personnel and systems to improve safety, efficiency and well-being. Thus, human factors include such attributes as: human physiology; psychology (including perception, cognition, memory, social interaction, and error); workplace design; environmental conditions; human-machine interface; and anthropometrics (the scientific study of measurements of the human body). 1-8 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General 1-9 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General What is Unique human factors issues in aviation maintenance Maintenance personnel are confronted with a set of human From a human factors perspective, maintenance personnel factors unique within aviation. Maintenance technicians work in have more in common with doctors and surgeons than with a more hazardous environment than most other jobs. The work pilots. may be carried out at heights, confined spaces, or in the bitter cold or sweltering heat. The work can be physically strenuous, We know from medicine that doctor-caused injury can yet it requires clerical skills and attention to detail. Maintenance significantly threaten patient health. Medical errors include technicians commonly spend more time preparing for a task surgical instruments sewn up inside patients, misdiagnosed than carrying it out. Dealing with documentation is crucial, and disorders, and, occasionally, surgeons operating on the wrong maintenance engineers typically spend nearly as much time limb. Most aircraft maintenance personnel are familiar with wielding a pen as they do holding a screwdriver. The work these types of errors. Opening up a healthy patient regularly to requires good communication and coordination, yet verbal check that organs function normally would not be an communication can be difficult due to noise levels and the use appropriate strategy in health care. Yet, preventative of hearing protection. The work frequently involves fault maintenance in aviation often requires us to disassemble and diagnosis and problem-solving in the presence of time inspect normally functioning systems, with the attendant risk of pressures, particularly at the gate. error. Maintenance personnel also face unique sources of stress. Air Just as medicine can be about preventing or responding to a traffic controllers and pilots can leave work at the end of the condition, maintenance can be divided into two categories. day, knowing that the day’s work is complete. In most cases, These are scheduled and unscheduled maintenance. The any errors they made during their shift had an immediate or no distinction between these two categories has significant impact. In contrast, when maintenance personnel leave work at implications for the maintenance human factors. the end of their shift, they know that the work they performed is relied on by crew and passengers for months or years into the future. The emotional burden on maintenance personnel whose work has been involved in accidents is mainly unrecognised outside the maintenance fraternity. On more than one occasion, maintenance personnel have taken their own lives following aircraft accidents caused by maintenance errors. 1-10 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General From a human-factors perspective, maintenance personnel have more in common with doctors and surgeons than with pilots 1-11 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General Scheduled maintenance tasks are typically preventative. Many preventative tasks are performed regularly, and so are familiar routines for maintenance personnel. Experienced personnel are unlikely to make mistakes related to a lack of knowledge or skills on a familiar preventative task. Maintenance discrepancies on familiar tasks are more likely to involve breakdowns in teamwork, simple absent-minded mistakes such as forgetting to install components, and action slips where a person performs a routine action they had not intended to. Unscheduled tasks are usually corrective and are performed in response to unplanned events such as aircraft damage or component failure. Although some unscheduled tasks are minor, others require extensive system knowledge, problem- solving and specialised skills. 1-12 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General 1-13 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General Incidents and accidents attributable to human factors/human error The statistics In 1940, it was calculated that approximately 70% of all aircraft As can be seen from the list, maintenance and inspection accidents were attributable to people’s performance, that is to deficiencies are one of the major contributory factors to say, human error. When the International Air Transport accidents. Association (IATA) reviewed the situation 35 years later, they found that there had been no reduction in the human error A similar exercise in 1998, looked at the causes of 621 global component of accident statistics. fatal accidents between 1980 and 1996. Again, the area ‘maintenance or repair oversight/error/inadequate’ was one of A study was carried out in 1986 in the USA, looking at the top 10 primary causal factors. significant accident causes in 93 aircraft accidents. These were as follows: It is clear from such studies that human factors problems in aircraft maintenance engineering are a significant issue, Causes/major contributory factors % of accidents in which warranting serious consideration. 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 The improper decision to land 6 1-14 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General The dominant role played by human performance in civil aircraft accidents 1-15 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General Japan Airlines, Boeing 747, 1985 In August 1985, the world’s worst single-aircraft accident claimed the lives of 520 people when a Boeing 747-100, operated by Japan Airlines, became uncontrollable and crashed into a mountain. The aircraft had departed Tokyo on a short flight to Osaka. As the aircraft reached its cruising altitude of 24,000 ft, the cabin suffered a sudden decompression due to the failure of the rear pressure bulkhead. The escaping air caused severe damage, separating most of the vertical stabiliser and rudder. In addition, hydraulic lines were breached, and hydraulic pressure was lost from all four systems. The flight crew attempted to steer the aircraft using engine power. However, they could not maintain control, and after about 30 minutes, the aircraft crashed into a mountain northwest of Tokyo. The investigators found that the rear pressure bulkhead had failed in flight due to a fatigue fracture in an area where a repair had been made years previously after the aircraft had sustained a tail scrape. The repair included replacing the lower half of the bulkhead. The new lower half should have been spliced to the upper half using a doubler plate extending under three lines of rivets. However, as shown below, part of the splice was made using two plates instead of a single plate as intended. As a result, the join relied on only a single row of rivets. After the repair, the aircraft flew over 12,000 flights and underwent six C checks before the accident occurred. The accident highlighted the potential for maintenance errors to remain dormant for long periods before having their effect. 1-16 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024  Module 9.1 General The repair to the rear pressure bulkhead as specified in the repair instructions (left), and repair as actually carried out (right) 1-17 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General Eastern Airlines, L-1011, 1983 The Lockheed L-1011, with ten crewmembers and 162 Eighteen months before the accident, the airline had begun a passengers on board, was on a flight from Miami, US, to practice of removing and inspecting magnetic chip detectors Nassau, Bahamas. During the descent into Nassau, the low oil (MCDs) at 22-hour intervals whenever the aircraft was pressure light on the centre engine illuminated. The engine was overnighted at an Eastern Airlines maintenance station. Each shut down, and the captain decided to return to Miami on the removed MCD would then be inspected for metal particles two remaining engines. which would be an early warning of engine failure. Since the Rolls Royce recommendation had been implemented, airline The aircraft was cleared for the return and began a climb to maintenance personnel had changed over 100,000 chip flight level 200 (20,000 ft). While en route to Miami, the low oil detectors. It was estimated that the average line maintenance pressure lights for the two wing-mounted engines illuminated. engineer would have performed the task at least 100 times. Then, the right engine flamed out 15 minutes after the centre Other major airlines in the US that were also performing these engine had been shut down. Five minutes later, while the flight checks had decided to leave the O-ring seals on each chip crew attempted to restart the centre engine, the left engine detector in place unless they were damaged or worn. Eastern flamed out. The aircraft began a descent without power from Airlines, however, decided to fit new O-rings each time the 13,000 ft, and the passengers were instructed to don lifejackets MCDs were replaced. in preparation for a ditching. At about 4,000 ft, the crew managed to restart the centre engine. The aircraft made a one- At 1:30 AM on the morning of the accident, two airframe and engine landing at Miami International Airport 30 minutes after power plant engineers were assigned to change the MCDs on the emergency had begun. There were no injuries to the all three aircraft engines. Previously, MCDs had always been occupants. obtained from the foreman’s office, so one of the engineers went to the foreman’s office to pick up three MCDs to replace The investigation revealed that magnetic chip detectors had the three that would be removed. However, no MCDs were been installed without O-rings on all three engines, allowing oil available in the foreman’s office, so he went to the stock room to leak from the engines in flight. Although the engine problems and obtained three MCDs, each in a semi-transparent bag with resulted from maintenance errors, the investigation uncovered a serviceable tag attached. deeper organisational issues. The figure below represents the magnetic chip detector system on the RB-211 engine. 1-18 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General The magnetic chip-detector plug and housing on the RB-211-22B engine 1-19 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General This engineer then replaced the MCDs on the wing-mounted Aloha Airlines, Boeing 737, 1988 engines, using the headlights of a tug to provide illumination. In April 1988, an Aloha Airlines Boeing 737-200 en-route from To replace each MCD, he had to reach about 12 centimetres Hilo, Hawaii to Honolulu, experienced an explosive inside the oil service door on each engine, and with no direct decompression in which approximately 18 feet of cabin skin view of the task, he performed the replacement entirely by feel. and structure aft of the cabin entrance door and above the He did not check for the presence of O-rings because he passenger floor line separated from the aircraft. A flight assumed that each MCD was serviceable, having come with a attendant who was standing in the aisle was immediately swept serviceable tag and because, in his experience, MCDs had overboard. The flight diverted to Maui, where an emergency always come with O-rings fitted. The second engineer also landing was made (see below). knew that the MCDs had come with serviceable tags attached and, assuming they were ready to be fitted, used a lift truck to The NTSB concluded that the accident was caused by the reach the tail-mounted centre engine. Once fitted, all three failure of Aloha Airlines to detect the presence of significant engines were motored on the starter for about 10 seconds to disbonding and fatigue damage that ultimately led to the failure check for oil leaks. This standard check did not reveal any of the lap joint and the separation of part of the fuselage. As a leaks. result of the accident, the human factors of inspection became a significant issue of concern, particularly in the United States. The accident flight was not the first time the airline had experienced problems with the installation of MCDs. Over 20 months before the accident, the airline experienced 12 separate incidents involving in-flight engine shutdowns and unscheduled landings due to problems with O-ring seals and magnetic chip detector installation problems. The US National Transport Safety Board (NTSB) reported: ‘In every incident...management investigated the circumstances and concluded that the problem was with the mechanics and not the maintenance procedure.’ Rather than addressing the wider system problems, such as poor procedures and undocumented norms, the incidents resulted in individual disciplinary action and training. The accident highlighted the potential for preventative maintenance to introduce risk and how a single error could be carried across multiple systems. 1-20 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General Aloha Flight 243 after landing 1-21 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General British Airways, BAC 1-11, 1990 On 10 June 1990 in the UK, a BAC1-11 (British Airways flight 5390) was climbing through 17,300 feet on departure from Birmingham International Airport. The left windscreen, which had been replaced before the flight, was blown out under cabin pressure when it overcame the retention of the securing bolts because 84 out 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 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 store man 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 off, the procedures not requiring a pressure check or duplicated check. Several human factors contributed to this incident, including perceptual errors made by the SMM when identifying the replacement bolts, poor lighting in the store area, failure to wear spectacles, circadian effects, working practices, and possible organisational and design factors. 1-22 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General A reconstruction of the cockpit incident of British Airways flight 5390 1-23 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General Air Midwest, Beech 1900D, 2003 On 8 January 2003, Air Midwest flight 5481 crashed shortly However, the engineer and the inspector misunderstood the after take-off from Charlotte, North Carolina, killing the two technical procedure and thought it was only necessary to crewmembers and all 19 passengers aboard. The NTSB perform the steps related explicitly to adjusting the cable established that the pilots could not control the aircraft’s pitch tension. One of the steps skipped from the rigging procedure after take-off. There were two reasons for this. First, the aircraft would have required a cross-check of elevator positions with a was overloaded and had an aft centre of gravity that exceeded read-out from the aircraft’s flight data recorder at the end of the limits. maintenance procedure. This step may have alerted the engineer that the full elevator travel range was unavailable. Second, the elevator control system did not have the full range of nose-down travel due to incorrect rigging during a After the engineer had finished adjusting the control cable, he maintenance visit just over 24 hours before the accident. The checked the movement of the controls from the cockpit. The accident flight was the aircraft’s tenth flight after the inspector performed a physical check of the elevators, including maintenance work, yet the previous nine flights all involved grasping the elevator and moving it through its available travel. lower passenger loads and a centre of gravity further forward. He concluded that the travel was within limits. On the night of 6 January, the aircraft underwent a scheduled At the time of the accident, there was no requirement for a post- maintenance check that included checking the tension of the maintenance functional check after the control cable rigging. elevator control cables. Finding that the cable tension was less Such a check would have involved an engineer in the cockpit than required, the engineer performed selected steps from the moving the control wheel through its full forward and aft range elevator-control-system rigging procedure to tighten the cable of movement while an engineer positioned at the aircraft’s tail tension using cable turnbuckles. The engineer was performing measured the elevator deflection using a travel board. this task for the first time and was receiving on-the-job training from a quality assurance inspector. Five weeks after the accident, the aircraft manufacturer added a post-maintenance functional check to its elevator control However, tightening the cables, he inadvertently restricted the rigging procedure. The accident highlighted the difficulties of nose-down elevator travel to about half of what should have capturing maintenance errors once they have been made. The been available. NTSB noted that the US Federal Aviation Administration (FAA) did not have a general requirement for complete functional The maintenance manual for the Beech 1900D did not have an checks to be performed after maintenance on critical flight isolated task procedure for adjusting cable tension; instead, the systems or components. manufacturer specified that the entire rigging procedure should be followed. 1-24 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General The Beech 1900 involved in the accident. The cable adjustment turnbuckles on the elevator control cables 1-25 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General Excalibur Airways, Airbus A320, 1993 An incident in the UK in August 1993 involved an Airbus A320, In both of these UK incidents, their companies considered the which exhibited an undemanded roll to the right after take-off engineers involved well-qualified, competent and reliable during its first flight after a flap change. The aircraft returned to employees. All of the incidents were characterised by the Gatwick and landed safely. The investigation discovered that following: during maintenance, to replace the right outboard flap, the spoilers had been placed in maintenance mode and moved there were staff shortages; using an incomplete procedure; specifically, the collars and time pressures existed; flags were not fitted. The engineers did not fully understand the all the errors occurred at night; purpose of the collars and how the spoilers functioned. This shift or task handovers were involved; misunderstanding was due, in part, to the familiarity of the they both involved supervisors doing long hands-on tasks; engineers with other aircraft (mainly 757) and contributed to a there was an element of a ‘can-do’ attitude; lack of adequate briefing on the status of the spoilers during the interruptions occurred; shift handover. The locked spoiler was not detected during there was some failure to use approved data or company standard pilot functional checks. procedures; manuals were confusing; and British Midland, Boeing 737-400, 1995 there was inadequate pre-planning, equipment or spares. In the UK in February 1995, a Boeing 737-400 lost 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 almost all the oil loss from both engines during flight. The line engineer was originally going to carry out the task, but he swapped jobs with the base maintenance controller for various reasons. The base maintenance controller did not have the appropriate paperwork with him. Despite many interruptions, the base maintenance controller and a fitter did the task 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. 1-26 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General Spoilers deployed Borescoping an engine 1-27 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General The error chain In aviation the term “error chain” refers to the concept that many contributing factors typically lead to an accident rather than one single event causing the accident. These contributing factors stem from human-factor related errors rather than mechanical malfunctions. In the examples, the accident or incident was preventable and could have been avoided if things had been done differently. In some cases, several individuals were involved, and the outcome could have been modified if one had reacted or queried a particular action. In each situation, however, the individuals failed to recognise signs of potential hazards, did not react as expected or allowed themselves to be diverted from giving their attention to the task at hand, leaving themselves open to the likelihood of committing an error. All the examples involved a series of human factors and 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. 1-28 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General The error chain If we can break just one link in the chain, the accident/incident is prevented 1-29 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General Murphy’s law There is a tendency among human beings towards The contractor’s project manager kept a list of ‘laws’ and added complacency. The belief that an accident will never happen to this one, which he called Murphy’s Law. He took an old law that ‘me’ can be a significant problem when attempting to convince had been around for years in a more basic form and gave it a people of the need to take human factors issues seriously, name. recognise risks and implement improvements. Shortly afterwards, the Air Force doctor, Dr John Paul Stapp, who rode a sledge on the deceleration track to a stop, pulling Murphy’s law can be regarded as the notion: 40 Gs, gave a press conference. He said their excellent safety record on the project was due to a firm belief in Murphy’s Law “If anything can go wrong, it will.” and the necessity to circumvent it. Murphy’s law was born. Aerospace manufacturers picked it up If everyone could be persuaded to acknowledge Murphy’s Law, and used it widely in their ads during the next few months, and it might help overcome the commonly held belief that “it will soon it was being quoted in many news and magazine articles. never happen to me”. The incidents and accidents described The Northrop project manager, George Nichols, had a few laws show that experienced, well-respected individuals can make of his own. Nichols’ Fourth Law says, “avoid any action with an errors, and accidents can occur in organisations previously unacceptable outcome.” thought to be safe. It is not true that accidents only happen to people who are irresponsible or ‘sloppy’. Murphy’s law or sod’s law? The original name for “if anything can go wrong, it will” was Origin sod’s law; it would happen to the poor sod who needed a Murphy’s law was conceived at Edwards Air Force Base in catastrophic event the least. Sod’s law has existed in many 1949 at North Base. forms for hundreds of years. In the English county of Yorkshire, It was named after Captain Edward Murphy, an engineer it has passed through several generations. working on Air Force Project MX981, a project designed to see how much sudden deceleration a person can stand in a crash. One day, after finding that a transducer was wired wrong, he cursed the technician responsible and said, “If there is any way to do it wrong, he’ll find it.” 1-30 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General 1-31 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024 Module 9.1 General 1-32 Copyright 2024 © Joramco Academy FOR TRAINING PURPOSE ONLY Issue 2 – June 2024