9. Hearing investigation technique to analyze the background factors of an accident

Preventing accidents and incidents depends on gaining a maximum amount of information about the situations in which these events occur and about what action was taken by people involved in these incidents. Hearing investigation are carried out with the people involved in such events (Fig.1). However, to date there is no standard guideline on how these investigation should be conducted, which means that the information collected is incomplete and often requires further enquiries or revisions. A hearing investigation technique was therefore developed which sets out guidelines to follow and the attitude to adopt during the process, (Fig.2) along with a pedagogical program to support implementation of the technique.

One of the key aspects of the hearing investigation process is to pay full attention when listening to the subject (the person concerned of the investigation scene). Before asking questions and checking facts, the subject is asked to recall the scene of the event, encouraging them to speak freely. This step is followed by a series of open questions asked from various angles, which cannot be answered by a simple "yes" or "no", such as "could you explain in detail the circumstances of − − − − " and "what would normally happen".

An analysis was carried out after applying the new method to verify if the output of the hearing investigation was different to content obtained under the previous methods. Results showed that when the new hearing investigation technique was used, the subject gave more information about background factors to the event, validating the effectiveness of the new approach (Fig 3).

Part of the new technique is also to improve acceptance of the investigation process and impression on subjects. To this end, the new technique emphasizes the benefit of a trusting work environment, efforts to associate measures to safety and should encourage better cooperation in future investigations.