Zoekresultaten

How does aviation industry measure safety performance?

In this paper we present a review of existing aviation safety metrics and we lay the foundation for our four-years research project entitled “Measuring Safety in Aviation – Developing Metrics for Safety Management Systems”. We reviewed state-of-the-art literature, relevant standards and regulations, and industry practice. We identified that the long-established view on safety as absence of losses has limited the measurement of safety performance to indicators of adverse events (e.g., accident and incident rates). However, taking into account the sparsity of incidents and accidents compared to the amount of aviation operations, and the recent shift from compliance to performance based approach to safety management, the exclusive use of outcomes metrics does not suffice to further improve safety and establish a proactive monitoring of safety performance. Although the academia and aviation industry have recognized the need to use activity indicators for evaluating how safety management processes perform, and various process metrics have been developed, those have not yet become part of safety performance assessment. This is partly attributed to the lack of empirical evidence about the relation between safety proxies and safety outcomes, and the diversity of safety models used to depict safety management processes (i.e. root-cause, epidemiological or systemic models). This, in turn, has resulted to the development of many safety process metrics, which, however, have not been thoroughly tested against the quality criteria referred in literature, such as validity, reliability and practicality.

Critical review of safety performance metrics

Various tools for safety performance measurement have been introduced in order to fulfil the need for safety monitoring in organisations, which is tightly related to their overall performance and achievement of their business goals. Such tools include accident rates, benchmarking, safety culture and climate assessments, cost-effectiveness studies, etc. The current work reviews the most representative methods for safety performance evaluation that have been suggested and applied by a variety of organisations, safety authorities and agencies. This paper discusses several viewpoints of the applicability, feasibility and appropriateness of such tools, based on the viewpoints of managers and safety experts involved in a relevant research that was conducted in a large aviation organisation. The extensive literature cited, the discussion topics, along with the conclusions and recommendations derived, might be considered by any organisation that seeks a realistic safety performance assessment and establishment of effective measurement tools.

By accident or design

An introduction of accidents’ classification based on their outcome control

Most safety oriented organizations have established their accidents classification taking into account the magnitude of the combined adverse outcomes on humans, assets and the environment without considering the accidents‟ potential and the actual attempts of the involved persons to intervene with the accident progress. The specific research exploited a large sample of an aviation organization accident records for an11 years‟ time period and employed frequency and chi-square analyses to test a new accident classification scheme based on the distinction among the safety events with or without human intervention on the accident scene, indicating the management or not of their ultimate consequences. Furthermore, the research depicted the effectiveness of personnel strains to alleviate the accident potential outcomes and studied the contribution of time, local and complexity factors on the accident control attempt and the humans‟ positive or negative interference. The specific newly proposed accident classification successfully addressed the “controlled” or “uncontrolled” traits of the safety events studies, prior their severities consideration, and unveiled the effectiveness of personnel efforts to compensate for the adverse accident march. The portion between controlled and uncontrolled accidents in terms of the human intervention along with the effectiveness of the later may comprise a useful safety performance indicator that can be adopted by any industry sector and may be recommended through international and state safety related authorities.

Evaluating advancements in accident investigations using a novel framework

Safety is monitored by various proactive and reactive methods, including the investigation of adverse accidents and incidents, which are collectively known as safety investigations. In this study we demonstrate how accident and incident investigation reports can be useful to identify implicit safety views and accident investigation approaches. An analysis framework was developed based on contemporary safety literature. The framework incorporates aspects such as hindsight bias, judgemental approach, proximal or distal focus, and the application of systemic versus sequential accident causation models. The framework was piloted through the analysis of sixteen (16) accident investigation reports published by a Nuclear Power Plant (NPP). The comments of independent researchers lead to framework refinements that increased the inter-rater reliability substantially. The initial results were validated through interviews with the staff of the NPP. Afterwards, the framework was applied to 52 air accident reports published by the Dutch Safety Board (DSB) from 1999 to 2013. Frequency calculations revealed the extent of new safety thinking embracement from the DSB, and Fisher’s Exact Test showed that none of the modern safety aspects has changed over time. The framework can be used to analyse accident investigation reports published by various organisations as means to identify implicit safety views and evolution of accident investigation practices over time. Further research will explore the reasons for potential gaps between theory and practice and contribute to minimizing such distance. Safety is monitored by various proactive and reactive methods, including the investigation of adverse accidents and incidents, which are collectively known as safety investigations. In this study we demonstrate how accident and incident investigation reports can be useful to identify implicit safety views and accident investigation approaches. An analysis framework was developed based on contemporary safety literature. The framework incorporates aspects such as hindsight bias, judgemental approach, proximal or distal focus, and the application of systemic versus sequential accident causation models. The framework was piloted through the analysis of sixteen (16) accident investigation reports published by a Nuclear Power Plant (NPP). The comments of independent researchers lead to framework refinements that increased the inter-rater reliability substantially. The initial results were validated through interviews with the staff of the NPP. Afterwards, the framework was applied to 52 air accident reports published by the Dutch Safety Board (DSB) from 1999 to 2013. Frequency calculations revealed the extent of new safety thinking embracement from the DSB, and Fisher’s Exact Test showed that none of the modern safety aspects has changed over time. The framework can be used to analyse accident investigation reports published by various organisations as means to identify implicit safety views and evolution of accident investigation practices over time. Further research will explore the reasons for potential gaps between theory and practice and contribute to minimizing such distance.

Correlation of changes in the employment costs and average task load with rates of accidents attributed to human error

Market competition and global financial uncertainty have been the principal drivers that impel aviation companies to proceed to budget cuts, including decreases in salary and work force levels, in order to ensure viability and sustainability. Under the concepts of Maslow and Herzberg’s motivation theories, the current paper unfolds the influence of employment cost fluctuations on an aviation organization’s accidents attributed to human error. This study exploited financial and accident data over a period of 13 years, and explored if rates of accidents attributed to human errors of flight, maintenance and ramp crews, correlate with the average employment expenditures (N=13). In addition, the study took into account the relationship between average task load (ratio of flying hours per employee) and accident rates related to human error since task load, as part of total workload, is a constraint of modern complex systems. The results revealed strong correlations amongst accident rates linked to human error with the average employment costs and task load. The use of more specific data per aviation organizational department and professional group may further validate the results of this study. Organizations that seek to explore the 2 association between human error and employment budget and task load might appropriately adapt the approach proposed.