Cognitive failure analysis for aircraft accident investigation

Abstract

The present studies were undertaken to investigate the applicability of an information processing approach to human failure in the aircraft cockpit. Using data obtained from official aircraft accident investigation reports, a database of accidents and incidents involving New Zealand civil aircraft between 1982 and 1991 was compiled. In the first study, reports were coded into one of three error stages proposed by Nagel (1988) and for the presence of any of 61 specific errors noted by Gerbert and Kemmler (1986). The importance of decisional factors in fatal crashes was noted. Principal components analysis suggested the presence of five different varieties of human failure. In the second study, a more detailed error taxonomy derived from the work of Rasmussen (1982) was applied to the data. Goal selection errors emerged as the most frequent kind of cognitive error in fatal accidents. Aircraft accident reports can be a useful source of information about cognitive failures if probed with an appropriate, theoretically-based, analysis of information processing errors. Such an approach could provide the accident investigators with a useful tool, and lead to a more complete understanding of human error in aviation.     

Using Neural Networks to predict HFACS unsafe acts from the pre-conditions of unsafe acts

Abstract

Human Factors Analysis and Classification System (HFACS) is based upon Reason’s organizational model of human error which suggests that there is a ‘one to many’ mapping of condition tokens (HFACS level 2 psychological precursors) to unsafe act tokens (HFACS level 1 error and violations). Using accident data derived from 523 military aircraft accidents, the relationship between HFACS level 2 preconditions and level 1 unsafe acts was modelled using an artificial neural network (NN). This allowed an empirical model to be developed congruent with the underlying theory of HFACS. The NN solution produced an average overall classification rate of ca. 74% for all unsafe acts from information derived from their level 2 preconditions. However, the correct classification rate was superior for decision- and skill-based errors, than for perceptual errors and violations.

Practitioner Summary: A model to predict unsafe acts (HFACS level 1) from their preconditions (HFACS level 2) was developed from the analysis of 523 military aircraft accidents using an artificial NN. The results could correctly predict approximately 74% of errors.     

A methodology for identifying human error in U.S. Navy diving accidents

OBJECTIVE: To better understand how human error contributes to U.S. Navy diving accidents. BACKGROUND: An analysis of 263 U.S. Navy diving accident and mishap reports revealed that the human factors classifications were not informative for further analysis, and 70% of mishaps were attributed to unknown causes; only 23% were attributed to human factors. METHOD: Five diving fatality reports were examined using the consensual qualitative research (CQR) method to develop a taxonomy of six categories and 21 subcategories for classifying human errors in diving. In addition, 15 critical incident technique (CIT) interviews were conducted with U.S. Navy divers who had been involved in a diving accident or near miss and analyzed using the dive team error taxonomy. RESULTS: Overall, failures in situation awareness and leadership were the most common human errors made by the dive team. CONCLUSION: The dive team human error taxonomy could aid in accident investigation and in the training and evaluation of U.S. Navy divers. APPLICATION: The development of the dive team human error taxonomy has generated a number of considerations that researchers should take into account when developing, or adapting, an error taxonomy from one industry to another.     

Human error and commercial aviation accidents: an analysis using the human factors analysis and classification system

OBJECTIVE: The aim of this study was to extend previous examinations of aviation accidents to include specific aircrew, environmental, supervisory, and organizational factors associated with two types of commercial aviation (air carrier and commuter/ on-demand) accidents using the Human Factors Analysis and Classification System (HFACS). BACKGROUND: HFACS is a theoretically based tool for investigating and analyzing human error associated with accidents and incidents. Previous research has shown that HFACS can be reliably used to identify human factors trends associated with military and general aviation accidents. METHOD: Using data obtained from both the National Transportation Safety Board and the Federal Aviation Administration, 6 pilot-raters classified aircrew, supervisory, organizational, and environmental causal factors associated with 1020 commercial aviation accidents that occurred over a 13-year period. RESULTS: The majority of accident causal factors were attributed to aircrew and the environment, with decidedly fewer associated with supervisory and organizational causes. Comparisons were made between HFACS causal categories and traditional situational variables such as visual conditions, injury severity, and regional differences. CONCLUSION: These data will provide support for the continuation, modification, and/or development of interventions aimed at commercial aviation safety. APPLICATION: HFACS provides a tool for assessing human factors associated with accidents and incidents.     

Development of a bespoke human factors taxonomy for gliding accident analysis and its revelations about highly inexperienced UK glider pilots

Low-hours solo glider pilots have a high risk of accidents compared to more experienced pilots. Numerous taxonomies for causal accident analysis have been produced for powered aviation but none of these is suitable for gliding, so a new taxonomy was required. A human factors taxonomy specifically for glider operations was developed and used to analyse all UK gliding accidents from 2002 to 2006 for their overall causes as well as factors specific to low hours pilots. Fifty-nine categories of pilot-related accident causation emerged, which were formed into progressively larger categories until four overall human factors groups were arrived at: ‘judgement’; ‘handling’; ‘strategy’; ‘attention’. ‘Handling’ accounted for a significantly higher proportion of injuries than other categories. Inexperienced pilots had considerably more accidents in all categories except ‘strategy’. Approach control (path judgement, airbrake and speed handling) as well as landing flare misjudgement were chiefly responsible for the high accident rate in early solo glider pilots.     

ACCLDENT-PRONENESS IN MOTOR-VEHICLE DRIVERS

Abstract

Motor-vehicle drivers were examined at interview and on visual tests. Each was classified as ‘ accident-prone.’. or ‘ safe ’ on the basis of his known- accident record -and the distance he said he had driven, those with a rate of 3 or more accidents per 100 000 miles being classified as ‘ accident-prone ’, those with a lower rate as ‘ safe ’. On this criterion there were 34 ‘ accident-prone ’ drivers to be compared with 74 ‘ safe ’.

All those who gave a history of definite nervous or mental illness were ‘ safe ’. Those who had had grammar-school education or its equivalent tended to be ‘ safe ’. The unmarried men tended to be ‘ accident-prone ’. A larger proportion of the ‘ accident-prone ’ had been convicted of traffic or other offences. No differences -were found between the ‘ accident-prone ’ and the ‘ safe ’ in the incidence of physical disabilities, eye or ear defects or psychosomatic complaints, or in personal qualities so far as these could be rated. Plans for further research into accident-proneness are briefly discussed.     

The process of processing: exploring the validity of Neisser's perceptual cycle model with accounts from critical decision-making in the cockpit

The perceptual cycle model (PCM) has been widely applied in ergonomics research in domains including road, rail and aviation. The PCM assumes that information processing occurs in a cyclical manner drawing on top-down and bottom-up influences to produce perceptual exploration and actions. However, the validity of the model has not been addressed. This paper explores the construct validity of the PCM in the context of aeronautical decision-making. The critical decision method was used to interview 20 helicopter pilots about critical decision-making. The data were qualitatively analysed using an established coding scheme, and composite PCMs for incident phases were constructed. It was found that the PCM provided a mutually exclusive and exhaustive classification of the information-processing cycles for dealing with critical incidents. However, a counter-cycle was also discovered which has been attributed to skill-based behaviour, characteristic of experts. The practical applications and future research questions are discussed.

Practitioner Summary: This paper explores whether information processing, when dealing with critical incidents, occurs in the manner anticipated by the perceptual cycle model. In addition to the traditional processing cycle, a reciprocal counter-cycle was found. This research can be utilised by those who use the model as an accident analysis framework.     

Analysis method for revealing human and organisational factors of occupational accidents with movement disturbance (OAMDs)

Abstract

Slips, trips and other movement disturbances account for 20 to 30% of recorded occupational accidents (OAs). The causal representations of these accidents hamper their prevention. An analysis method dedicated to occupational accidents with movement disturbance (OAMDs) has been developed to change these representations. In France, the causal tree method (CTM) is very commonly used for analysing OAs. An initial version of an OAMD analysis method, which overcomes the problems encountered when analysing these accidents using the CTM, has been developed. This OAMD analysis method was reviewed by six targeted prevention officers and as a result some proposals have been discarded and this initial version has been transformed into three additional CTM modules. The purpose of these modules is to identify human and organisational factors and provide a formal representation of damage caused, beyond bodily injuries.

Practitioner summary: A method for analysing occupational accidents triggered by a slip, a trip or any other movement disturbance has been developed in consideration of the practices and constraints in companies. In particular, this method allows us to highlight the human and organisational factors involved in the accident situation.

Abbreviations: OA: occupational accident; OAMD: occupational accident with movement disturbance; CTM: causal tree method     

The role of psychological factors in workplace safety

Workplace safety researchers and practitioners generally agree that it is necessary to understand the psychological factors that influence people's workplace safety behaviour. Yet, the search for reliable individual differences regarding psychological factors associated with workplace safety has lead to sparse results and inconclusive findings. The aim of this study was to investigate whether there are differences between the psychological factors, cognitive ability, personality and work-wellness of employees involved in workplace incidents and accidents and/or driver vehicle accidents and those who are not. The study population (N = 279) consisted of employees employed at an electricity supply organisation in South Africa. Mann–Whitney U-test and one-way ANOVA were conducted to determine the differences in the respective psychological factors between the groups. These results showed that cognitive ability did not seem to play a role in workplace incident/accident involvement, including driver vehicle accidents, while the wellness factors burnout and sense of coherence, as well as certain personality traits, namely conscientiousness, pragmatic and gregariousness play a statistically significant role in individuals' involvement in workplace incidents/accidents/driver vehicle accidents. Safety practitioners, managers and human resource specialists should take cognisance of the role of specifically work-wellness in workplace safety behaviour, as management can influence these negative states that are often caused by continuously stressful situations, and subsequently enhance work place safety.     

The ‘Wheel of Misfortune’: a taxonomic approach to human factors in accident investigation and analysis in aviation and other complex systems

The analysis and reporting of the human factors aspects of accidents in aviation and other complex systems continues to present difficulties for investigators and analysts alike. Reason's ‘latent conditions’ model has had a major impact on the way accidents are conceptualized but it has proven difficult to apply as a practical tool. Recent attempts to overcome these difficulties are discussed and an alternative conceptualization is proposed. This conceptualization is based on a blend of several well-supported theoretical models in cognitive engineering and can be used to formulate a parsimonious analysis system for the investigation and reporting of the human factors aspects of accidents. Two well-known examples of transportation disasters are briefly described and related to the proposed conceptual framework. The proposed framework serves three important functions in accident investigation and analysis: a heuristic function, an investigative function, and an integrative function.     

Risk assessment of parking lot management based on occupational injuries data

This study is concerned with the characteristics of occupational injuries and sick leaves for the workers doing parking lot management. Possible incidents and sick leaves have been identified and analyzed for 470 occupational accidents in the parking lot management process. Management level of accidents for prioritizing prevention measures is induced for the combination of the accident types and parking lot management processes. Accidents occurring during the specific parking lot management process showed different characteristics, depending on the type of accident and agency of accident. Most critical accidents that required corrective actions for prevention were being struck by an object in the “guide” process and slipping in the “valet parking” process. And, possible incidents predicted also as high level of management were slips in the “fee collection” and “cleaning” processes and falls to lower level in the “operating lift” and “repair” processes. Also, traffic accidents in the “guide” process, overexertion and bodily reaction and posture in the “patrol” process were ranked ‘high. The findings of this study can be used to develop more effective accident prevention policies to reduce occupational accidents in parking lot management.     

Unsafe acts and unsafe outcomes in aircraft maintenance

Road safety studies using the Driver Behaviour Questionnaire (DBQ) have provided support for a three-way distinction between violations, skill-based errors and mistakes, and have indicated that a tendency to commit driving violations is associated with an increased risk of accident involvement. The aims of this study were to examine whether the three-way distinction of unsafe acts is applicable in the context of aircraft maintenance, and whether involvement in maintenance safety occurrences can be predicted on the basis of self-reported unsafe acts. A Maintenance Behaviour Questionnaire (MBQ) was developed to explore patterns of unsafe acts committed by aircraft maintenance mechanics. The MBQ was completed anonymously by over 1300 Australian aviation mechanics, who also provided information on their involvement in workplace accidents and incidents. Four factors were identified: routine violations, skill-based errors, mistakes and exceptional violations. Violations and mistakes were related significantly to the occurrence of incidents that jeopardized the quality of aircraft maintenance, but were not related to workplace injuries. Skill-based errors, while not related to work quality incidents, were related to workplace injuries. The results are consistent with the three-way typology of unsafe acts described by Reason et al. (1990) and with the DBQ research indicating an association between self-reported violations and accidents. The current findings suggest that interventions addressed at maintenance quality incidents should take into account the role of violations and mistakes, and the factors that promote them. In contrast, interventions directed at reducing workplace injury are likely to require a focus on skill-based errors.     

Unsafe acts and unsafe outcomes in aircraft maintenance

Road safety studies using the Driver Behaviour Questionnaire (DBQ) have provided support for a three-way distinction between violations, skill-based errors and mistakes, and have indicated that a tendency to commit driving violations is associated with an increased risk of accident involvement. The aims of this study were to examine whether the three-way distinction of unsafe acts is applicable in the context of aircraft maintenance, and whether involvement in maintenance safety occurrences can be predicted on the basis of self-reported unsafe acts. A Maintenance Behaviour Questionnaire (MBQ) was developed to explore patterns of unsafe acts committed by aircraft maintenance mechanics. The MBQ was completed anonymously by over 1300 Australian aviation mechanics, who also provided information on their involvement in workplace accidents and incidents. Four factors were identified: routine violations, skill-based errors, mistakes and exceptional violations. Violations and mistakes were related significantly to the occurrence of incidents that jeopardized the quality of aircraft maintenance, but were not related to workplace injuries. Skill-based errors, while not related to work quality incidents, were related to workplace injuries. The results are consistent with the three-way typology of unsafe acts described by Reason et al. (1990) and with the DBQ research indicating an association between self-reported violations and accidents. The current findings suggest that interventions addressed at maintenance quality incidents should take into account the role of violations and mistakes, and the factors that promote them. In contrast, interventions directed at reducing workplace injury are likely to require a focus on skill-based errors.     

Flight-deck automation: promises and problems

Modern microprocessor technology and display systems make it entirely feasible to automate many of the flight-deck functions previously performed manually. There are many benefits to be derived from automation; the question today is not whether a function can be automated, but whether it should be, due to various human factors issues. It is highly questionable whether total system safety is always enhanced by allocating functions to automatic devices rather than human operators, and there is some reason to believe that flight-deck automation may have already passed its optimum point. This is an age-old question in the human factors profession, and there are few guidelines available to the system designer.

This paper presents the state-of-the-art in human factors in flight-deck automation, identifies a number of critical problem areas, and offers broad design guidelines. Some automation-related aircraft accidents and incidents are discussed as examples of human factors problems in automated flight.     

Associations between errors and contributing factors in aircraft maintenance

In recent years cognitive error models have provided insights into the unsafe acts that lead to many accidents in safety-critical environments. Most models of accident causation are based on the notion that human errors occur in the context of contributing factors. However, there is a lack of published information on possible links between specific errors and contributing factors. A total of 619 safety occurrences involving aircraft maintenance were reported using a self-completed questionnaire. Of these occurrences, 96% were related to the actions of maintenance personnel. The types of errors that were involved, and the contributing factors associated with those actions, were determined. Each type of error was associated with a particular set of contributing factors and with specific occurrence outcomes. Among the associations were links between memory lapses and fatigue and between rule violations and time pressure. Potential applications of this research include assisting with the design of accident prevention strategies, the estimation of human error probabilities, and the monitoring of organizational safety performance.     

Risk models for analyzing pilot-error at US airlines: a comparative safety study

Pilot-error is the major cause of accidents in airline operations. This paper proposes two risk models for analyzing pilot-error at US airlines. The focus is on whether airline-specific factors (the name of the airlines) are useful in predicting pilot-error. This is the first study that reliably models pilot-error accident and incident rates on an airline-by-airline basis. The results indicate that airline-specific factors generally were not useful predictors of pilot-error. Moreover, any predicted influence of an individual airline was substantially less than for the pilot-specific factors of age and experience. Thus, the paper illustrates the difficulty of trying to compare airlines on the basis of safety. By analyzing factors associated with pilot-error, policy-makers can more effectively manage and reduce the risk of airline accidents and incidents.     

What went right? An analysis of the protective factors in aviation near misses

Abstract

Learning from successful safety outcomes, or what went right, is an important emerging component of maintaining safe systems. Accordingly, there are increasing calls to study normal performance in near misses as a part of safety management activities. Despite this, there is limited guidance on how to accomplish this in practice. This article presents a study in which using Rasmussen’s risk management framework to analyse 16 serious incidents from the aviation domain. The findings show that a network of protective factors prevents accidents with factors identified across the sociotechnical system. These protective networks share many properties with those identified in accidents. The article demonstrates that is possible to identify these networks of protective factors from incident investigation reports. The theoretical implications of these results and future research opportunities are discussed.

Practitioner Statement: The analysis of near misses is an important part of safety management activities. This article demonstrates that Rasmussen?s risk management framework can be used to identify networks of protective factors which prevent accidents. Safety practitioners can use the framework described to discover and support the system-wide networks of protective factors.     

Multiple ergonomic interventions and transportation safety

This article discusses arguments and research evidence concerning multiple ergonomic approaches to problems of transportation safety. Transportation accidents ( and their consequences) are the result of multifactor processes. Therefore, the probability of an- accident ( and of an injury, given an accident) can be influenced by interventions directed at any of the factors. Furthermore, the most effective accident countermeasures are not necessarily those directed at the ‘ cause’ of accidents. As examples, multiple ergonomic countermeasures are noted for road accidents involving alcohol-intoxicated drivers and elderly drivers, as well as for minimizing injuries resulting from road accidents