Human error in European air traffic management: the HERA project

The majority of accidents in hazardous activities are caused by human error. This problem is not new, and a good deal of research, application, and development of practical techniques for the analysis, prediction and reduction of human errors or their negative effects, has occurred in a range of industries. Whilst human error within flight operations has for some time been the centre of exhaustive research and debate, a similar analysis within the field of air traffic management (ATM) is not so comprehensive. Therefore, it may be that ATM can learn from other industries.This paper deals with an approach to ATM incident analysis that is being developed in the European ATM arena. This new approach aims to determine how and why human errors are contributing to incidents, and thus how to improve human reliability within a high-reliability system. This developing approach is called ‘HERA’ — Human Error in ATM Project.The paper reports on a formative part, or phase 1, of a project that reviewed the theoretical and practical literature to determine the best conceptual framework upon which to base an ATM incident analysis tool. The conceptual framework chosen is that of human performance from an information processing perspective, which has been adapted to make it more contextually relevant to ATM. A prototype structure was adopted for a technique with which to analyse ATM incidents. This paper summarises the review of the literature surveyed, and briefly describes the structure of the prototype technique.     

Application of Human Factors Analysis and Classification System (HFACS) to UK rail safety of the line incidents

Minor safety incidents on the railway cause disruption, and may be indicators of more serious safety risks. The following paper aimed to gain an understanding of the relationship between active and latent factors, and particular causal paths for these types of incidents by using the Human Factors Analysis and Classification System (HFACS) to examine rail industry incident reports investigating such events. 78 reports across 5 types of incident were reviewed by two authors and cross-referenced for interrater reliability using the index of concordance. The results indicate that the reports were strongly focused on active failures, particularly those associated with work-related distraction and environmental factors. Few latent factors were presented in the reports. Different causal pathways emerged for memory failures for events such a failure to call at stations, and attentional failures which were more often associated with signals passed at danger. The study highlights a need for the rail industry to look more closely at latent factors at the supervisory and organisational levels when investigating minor safety of the line incidents. The results also strongly suggest the importance of a new factor – operational environment – that captures unexpected and non-routine operating conditions which have a risk of distracting the driver. Finally, the study provides further demonstration of the utility of HFACS to the rail industry, and of the usefulness of the index of concordance measure of interrater reliability.     

Routes to failure: analysis of 41 civil aviation accidents from the Republic of China using the human factors analysis and classification system

The human factors analysis and classification system (HFACS) is based upon Reason's organizational model of human error. HFACS was developed as an analytical framework for the investigation of the role of human error in aviation accidents, however, there is little empirical work formally describing the relationship between the components in the model. This research analyses 41 civil aviation accidents occurring to aircraft registered in the Republic of China (ROC) between 1999 and 2006 using the HFACS framework. The results show statistically significant relationships between errors at the operational level and organizational inadequacies at both the immediately adjacent level (preconditions for unsafe acts) and higher levels in the organization (unsafe supervision and organizational influences). The pattern of the 'routes to failure' observed in the data from this analysis of civil aircraft accidents show great similarities to that observed in the analysis of military accidents. This research lends further support to Reason's model that suggests that active failures are promoted by latent conditions in the organization. Statistical relationships linking fallible decisions in upper management levels were found to directly affect supervisory practices, thereby creating the psychological preconditions for unsafe acts and hence indirectly impairing the performance of pilots, ultimately leading to accidents.     

Human error data collection as a precursor to the development of a human reliability assessment capability in air traffic management

Quantified risk and safety assessments are now required for safety cases for European air traffic management (ATM) services. Since ATM is highly human-dependent for its safety, this suggests a need for formal human reliability assessment (HRA), as carried out in other industries such as nuclear power. Since the fundamental aspect of HRA is human error data, in the form of human error probabilities (HEPs), it was decided to take a first step towards development of an ATM HRA approach by deriving some HEPs in an ATM context.This paper reports a study, which collected HEPs via analysing the results of a real-time simulation involving air traffic controllers (ATCOs) and pilots, with a focus on communication errors. This study did indeed derive HEPs that were found to be concordant with other known communication human error data. This is a first step, and shows promise for HRA in ATM, since HEPs have been derived which could be used in safety assessments, although these HEPs are for only one (albeit critical) aspect of ATCOs’ tasks (communications). The paper discusses options and potential ways forward for the development of a full HRA capability in ATM.     

Operator error and system deficiencies: Analysis of 508 mining incidents and accidents from Queensland, Australia using HFACS

Historically, mining has been viewed as an inherently high-risk industry. Nevertheless, the introduction of new technology and a heightened concern for safety has yielded marked reductions in accident and injury rates over the last several decades. In an effort to further reduce these rates, the human factors associated with incidents/accidents needs to be addressed. A modified version of the Human Factors Analysis and Classification System was used to analyze incident and accident cases from across the state of Queensland to identify human factor trends and system deficiencies within mining. An analysis of the data revealed that skill-based errors were the most common unsafe act and showed no significant differences across mine types. However, decision errors did vary across mine types. Findings for unsafe acts were consistent across the time period examined. By illuminating human causal factors in a systematic fashion, this study has provided mine safety professionals the information necessary to reduce mine incidents/accidents further.     

Understanding the human factors contribution to railway accidents and incidents in Australia

Forty rail safety investigation reports were reviewed and a theoretical framework (the Human Factors Analysis and Classification System; HFACS) adopted as a means of identifying errors associated with rail accidents/incidents in Australia. Overall, HFACS proved useful in categorising errors from existing investigation reports and in capturing the full range of relevant rail human factors data. It was revealed that nearly half the incidents resulted from an equipment failure, most of these the product of inadequate maintenance or monitoring programs. In the remaining cases, slips of attention (i.e. skilled-based errors), associated with decreased alertness and physical fatigue, were the most common unsafe acts leading to accidents and incidents. Inadequate equipment design (e.g. driver safety systems) was frequently identified as an organisational influence and possibly contributed to the relatively large number of incidents/accidents resulting from attention failures. Nearly all incidents were associated with at least one organisational influence, suggesting that improvements to resource management, organisational climate and organisational processes are critical for Australian accident and incident reduction. Future work will aim to modify HFACS to generate a rail-specific framework for future error identification, accident analysis and accident investigation.     

Designing for safety: the ‘free flight’ air traffic management concept

This paper describes the conceptual design and validation of an air traffic management (ATM) concept and the role the safety and human factors played in this design and validation process. The free flight (FF) concept is characterised by being a direct route concept where the pilots, instead of the air traffic controller, are responsible for the separation assurance. Moving this task to the cockpit has consequences for the man machine interface in the cockpit, which needs to be modified to accommodate this new task (micro level design). On top of that, a set of rules and procedures are required to ensure an efficient and safe traffic flow (macro level design). Both the micro and macro aspect of this design are intertwined and require an accurate tuning to arrive at an overall acceptable solution. Both micro-level (flight simulator) experiments and macro-level (traffic simulations) experiments have been conducted to investigate the feasibility of this concept after optimising the initial conceptual design.     

A non-probabilistic prospective and retrospective human reliability analysis method — application to railway system

The paper describes a method to analyze human reliability. It defines human reliability as a degradation function related to deviations of both human behavioral state and system state due to this behavior. The method is called ACIH, a French acronym for Analysis of Consequences of Human Unreliability. It is a non-probabilistic approach, which aims at identifying both tolerable and intolerable sets of human behavioral degradations, which may affect the system safety. The corresponding scenarios of degradations are characterized by a behavioral model of unreliability including three main factors: acquisition related factors, problem solving related factors, and action related factors. Both prospective and retrospective analyses are taken into account to specify error prevention tools. They are applied to the railway system.     

A critical view of severity classification in risk assessment methods

The knowledge of operational experts plays a fundamental role in performing safety assessments in safety critical organizations. The complexity and socio-technical nature of such systems produce hazardous situations which require a thorough understanding of concrete operational scenarios and cannot be anticipated by simply analysing single failures of specific functions. This paper addresses some limitations regarding state-of-the-art safety assessment techniques, with special reference to the adoption of “chain of event” models in accident causation (widely criticised by many authors), to the use of severity classes and to the adoption of the worst credible effect criterion. Such methods tend to assume a linear link between single hazards considered in isolation and corresponding consequences for safety, thus neglecting the intrinsic complexity of the systems under analysis and reducing the opportunities for an effective involvement of operational experts. An alternative approach is proposed to overcome these limitations, by distinguishing different typologies of hazards and integrating the analysis of single functions with the study of concrete operational scenarios.     

Recovery from equipment failures in ATC: Determination of contextual factors

Human reliability assessment (HRA) currently uses various approaches to determine and quantify human error. These approaches are increasingly being employed in various safety-critical domains, such as air traffic management and its ground component air traffic control. HRA research over the years has shown the important role of the context in which human errors take place. Recent techniques now put more emphasis on the definition of key contextual factors and their impact on the reliability of human performance. This paper presents a review of the current understanding of contextual factors in various industries. It uses this together with results from controller interviews to identify the contextual factors relevant to controller recovery from equipment failures in air traffic control. These factors should be used in conjunction with an appropriate method to analyse the performance of a controller during the process of recovery from failures.     

Human and organisational factors in maritime accidents: Analysis of collisions at sea using the HFACS

Over the last decade, the shipping industry has implemented a number of measures aimed at improving its safety level (such as new regulations or new forms of team training). Despite this evolution, shipping accidents, and particularly collisions, remain a major concern. This paper presents a modified version of the Human Factors Analysis and Classification System, which has been adapted to the maritime context and used to analyse human and organisational factors in collisions reported by the Marine Accident and Investigation Branch (UK) and the Transportation Safety Board (Canada).     

Agent-based organizational modelling for analysis of safety culture at an air navigation service provider

Assessment of safety culture is done predominantly by questionnaire-based studies, which tend to reveal attitudes on immaterial characteristics (values, beliefs, norms). There is a need for a better understanding of the implications of the material aspects of an organization (structures, processes, etc.) for safety culture and their interactions with the immaterial characteristics. This paper presents a new agent-based organizational modelling approach for integrated and systematic evaluation of material and immaterial characteristics of socio-technical organizations in safety culture analysis. It uniquely considers both the formal organization and the value- and belief-driven behaviour of individuals in the organization. Results are presented of a model for safety occurrence reporting at an air navigation service provider. Model predictions consistent with questionnaire-based results are achieved. A sensitivity analysis provides insight in organizational factors that strongly influence safety culture indicators. The modelling approach can be used in combination with attitude-focused safety culture research, towards an integrated evaluation of material and immaterial characteristics of socio-technical organizations. By using this approach an organization is able to gain a deeper understanding of causes of diverse problems and inefficiencies both in the formal organization and in the behaviour of organizational agents, and to systematically identify and evaluate improvement options.     

Evaluation of air traffic management procedures—safety assessment in an experimental environment

This paper presents and discusses the application of safety assessment methodologies to a pre-operational project in the Air Traffic Control field. In the case analysed in the present paper a peculiar aspect was the necessity to effectively assess new operational procedures and tools. In particular we exploited an integrated methodology to evaluate computer-based applications and their interactions with the operational environment. Current ATC safety practices, methodologies, guidelines and standards were critically revised, in order to identify how they could be applied to the project under consideration. Thus specific problematic areas for the safety assessment in a pre-operational experimental project are highlighted and, on the basis of theoretical principles, some possible solutions taken into consideration. The latter are described highlighting the rationale of most relevant decisions, in order to provide guidance for generalisation or re-use.     

An extension of the Human Factors Analysis and Classification System for use in open systems

The Human Factors Analysis and Classification System (HFACS), based upon Reason's model of human error in an organisational context, is currently the most widely used human factors accident analysis framework. However, it has been criticised for merely categorising accident data rather than analysing it. Previous research has established statistical associations between the levels and categories within HFACS but has not specified a mechanism by which one category influences subsequent behaviour. This paper extends the approach in two ways. Using the categories of control flaws derived from Leveson's Systems–Theoretical Accident Model and Processes (STAMP) approach, it describes the mechanisms by which categories within HFACS are associated with other categories lower in the organisational hierarchy. It also provides a mechanism by which active failures can promulgate across organisations. The revised methodology HFACS-STAMP is illustrated using the case study of the Uberlingen mid-air collision on 1 July 2002.     

Rider errors and amusement ride safety: observation at three carnival midways

Over 5000 ride-exposures were observed at three carnival midways, with 103 ride installations. Rider and operator behaviour was observed and compared with posted safety regulations. The observed errors were analysed and clustered qualitatively and quantitatively. Rider errors were seen in 1.4% of individual ride-exposures, and little operator interception was seen. Most errors of both riders and operators were mistakes rather than slips or lapses, and many were violations. Qualitative typology based on error context indicated that social goals, sensory enhancement or convenience goals made sense of most mistakes. The most common single behaviour observed contrary to posted rules was leaning out or extending limbs. Future interventions should consider whether ride features could guide or support riders in achieving their goals rather than obstructing or prohibiting specific behaviours.     

Combining task analysis and fault tree analysis for accident and incident analysis: A case study from Bulgaria

Understanding the reasons for incident and accident occurrence is important for an organization's safety. Different methods have been developed to achieve this goal. To better understand the human behaviour in incident occurrence we propose an analysis concept that combines Fault Tree Analysis (FTA) and Task Analysis (TA). The former method identifies the root causes of an accident/incident, while the latter analyses the way people perform the tasks in their work environment and how they interact with machines or colleagues. These methods were complemented with the use of the Human Error Identification in System Tools (HEIST) methodology and the concept of Performance Shaping Factors (PSF) to deepen the insight into the error modes of an operator's behaviour. HEIST shows the external error modes that caused the human error and the factors that prompted the human to err. To show the validity of the approach, a case study at a Bulgarian Hydro power plant was carried out. An incident – the flooding of the plant's basement – was analysed by combining the afore-mentioned methods. The case study shows that Task Analysis in combination with other methods can be applied successfully to human error analysis, revealing details about erroneous actions in a realistic situation.     

An industry survey of the screw press system in palm oil mills: Operational data and malfunction issues

Research questionnaires were disseminated to active palm oil mills across Malaysia to acquire information on (i) the mill operation, and (ii) any malfunction issues concerning the screw press system. A total of 105 mills responded to the survey (response rate = 25%). The relationship between the mill operational data (processing capacity, daily operation cycle), the screw press system (type, quantity), and the malfunction frequency was examined. The double screw press machine dominated the palm oil milling industries due to its larger capacity that entails a shorter processing time in comparison with the single screw press. Recurring malfunction problems were prevalent in both types of screw press system. While fatigue, corrosion, wear and tear are inevitable due to the heavy usage and natural causes, an irregular maintenance schedule and poor handling topped the list of common cause for malfunction of the screw press.     

齿轮传动系统损伤检测与多故障分类研究

研究了数据挖掘的支持向量机的智能故障检测与诊断方法。通过对齿轮系统在不同的运转状态下的工作状况进行试验测试分析,获取了有关的测试信号,并对不同的故障振动特征信号进行了特征提取与分析研究。在此基础上将支持向量机引入到齿轮传动的损伤检测与诊断之中,建立了两分类和多分类分类器,研究了支持向量机的两分类和多类分类算法。通过分析处理、训练和测试仿真数据以及齿轮振动特征信号,对齿轮系统在各种不同转速下不同故障进行了预测、分类和诊断。研究表明, 支持向量机能够很好的区分不同运转状况下各种典型齿轮损伤与故障,低转速下识别率更高,为95%,特别是对各种复合类故障具有较高的识别精度、识别率在81%以上。它在齿轮故障诊断中具有较好诊断识别能力与发展前景,是一种有效地损伤检测与诊断新方法。     

Human error risk management for engineering systems: a methodology for design, safety assessment, accident investigation and training

The objective of this paper is to tackle methodological issues associated with the inclusion of cognitive and dynamic considerations into Human Reliability methods. A methodology called Human Error Risk Management for Engineering Systems is presented that offers a ‘roadmap’ for selecting and consistently applying Human Factors approaches in different areas of application and contains also a ‘body’ of possible methods and techniques of its own. Two types of possible application are discussed to demonstrate practical applications of the methodology. Specific attention is dedicated to the issue of data collection and definition from specific field assessment.     

Log classification in the hardwood timber industry: method and value analysis

Natural resources industries, such as the forest product industry, must deal with variable input material, which affects their efficiency and their ability to accurately predict output yields. In order to address this, the industry can use technologies that adapt to variable input, or plan its operations taking variability into account. In the Canadian softwood lumber industry, the first approach is used with the adoption of advanced technologies that adapt sawing patterns to logs’ and work-in-process characteristic using scanners technology. Another approach to deal with material variability is input material classification. Specific characteristics can be measured to classify input material and reduce variability within each class. However, whether the process involves logs, mining ores or recycled papers, material classification has both a value and a cost. This paper first proposes a method based on classification tree analysis to classify hardwood logs. Next, using agent-based simulation, it analyses the value of different classification strategies, from detailed, to no classification at all. Results show in the context of the Québec hardwood lumber industry that the benefit of detailed classification is offset by its cost, while a relatively simple classification strategy dramatically improves output yield at relatively low cost.