How does aviation industry measure safety performance? Current practice and limitations

This paper reviewed state-of-the-art literature about existing aviation safety metrics. 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. 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. Although the need to use activity indicators is recognised, 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 outcomes and the diversity of safety models used (i.e., root-cause, epidemiological or systemic models). This has resulted to the development of many safety process metrics, which have not been thoroughly tested against the quality criteria.