Understanding and Interpreting Safety

“The most important part of the safety enterprise is thinking about how to think (and, therefore, how to act) about risk” (Wildavsky, 1988, p. 2). So, how do investigators understand safety? And how do they think about risk? The answers to these questions are fundamental to explaining how risk is analysed and safety is managed in practice. Traditionally, risk is viewed in terms of future harm: the likelihood and severity of future adverse outcomes. Safety is commonly defined as a double negative — the absence of harm or the avoidance of risk — captured pithily by the granite sign standing outside the offices of the UK’s aviation regulator that reads ‘Safety is no accident’. But flight safety investigators do not entirely agree. The absence of harm or the avoidance of adverse outcomes can at times be helpful indicators, but they do not tell the whole story. Investigators work in a context where errors and incidents are profligate, where the potential consequences of accidents are catastrophic, but where actual harmful events are extraordinarily rare. As such, investigators draw on a shared practical theory of safety that is both more nuanced and more pragmatic than traditional ideas that focus on the prediction or absence of harmful outcomes. Understanding the nature and substance of this practical theory of safety is essential if we are to understand how safety investigators work to analyse risk and improve safety.