Witnesses are one of the primary sources of evidence investigators can utilise when covering an accident. Information obtained from witnesses may provide key aspects such as: whether there was any damage to the aircraft prior to impact; any unusual noises or sounds; was there any sign of smoke or gas in the cabin beforehand and, was the aircraft flying erratically before the respective accident.
Investigators do need to be aware that not all witnesses may have the same information – nor may they have the same technical knowledge or awareness as other witnesses. This is one reason why investigators group witnesses into five distinct categories with each group related to key aspects of the accident.
This first grouping are those that participated in the actual accident and may include crew members, passengers or even people on the ground who were directly involved. People in this category may provide key aspects about how the aircraft was flying and if any special events were at play prior to the accident – i.e. erratic flying, any unusual sounds, smells in the cabin etc. The second group is for those who either saw or heard the accident (or part there-of). These people may also provide key information about how the aircraft was flying prior to or during the accident but the difference with this group compared to the first is that the second group may have an observer’s point of view – as opposed to being directly involved. Local people to the accident scene form the third grouping as they can provide key information on local conditions – including such aspects as environmental, meteorological conditions, positioning of sun, traffic, etc.
Those witnesses who may have seen, heard or experienced the events prior to the actual accident occurring fall into the fourth grouping. These people may hold key information about the sequence of events leading up to the accident. This information could include aspects such erratic flying, weather conditions or any unusual or abnormal events. The final grouping is for those that have background knowledge relating to the accident. This may involve information from maintenance crew, previous passengers or flight crews from the same aircraft and even other crews who flew in the same region prior to the accident occurring.
Interviewing the witnesses (regardless of category) is not a simple process and is one that involves a high level of controlled dynamic adaptation – that is, listening to (and recording) the responses and adjusting further questioning and interviewing techniques during the interview and making adjustments based on how the witness responds.
Other techniques include adapting the questioning for those that may have a different perspective – be it, technical (cabin and flight crew) or social and psychological (survivors and direct witnesses). Each of these witnesses may perceive and report events in a different manner and the interviewer will need the ability to adapt or consider the circumstances and questions for each interviewee – especially when questioning next of kin.