In the early 1970s, the National Transportation Safety Board developed a guide for the investigation of accidents. NTSB found that all collisions and adverse events could be broken into three time periods: pre-incident, incident, and post-incident. All accidents also could be divided into three causation factor categories: human, vehicle, and environmental.

Causation Factors

Human factors include the drivers of all involved vehicles, operators of any machinery or equipment, pilots, secretaries who fall from chairs, and witnesses. Human factors encompass anyone and everyone who has anything to do with the incident. This could include supervisors, trainers, managers, and co-workers.

Device or vehicle factors pertain to the manner in which the device caused the event, be it a pipeline, railroad car, or aircraft. For a machine operator, this would include design factors, safety devices, alterations to devices, interior contact points within vehicles, prior device failures, and repair and maintenance histories, as well as how well the device reacted to the event.

The third causation factor is the environment, which takes into consideration whether the area in which the event occurred contributed to the event. For a slip and fall incident, for example, the interviewer would want to know what the surface was made of. Was it clean, dry, level? When was it last serviced? For a traffic collision, what is the accident history of the area? Are there traffic controls? Did they function? Were they necessary? In what way was the area altered by the incident?

Time Periods

The pre-incident period starts with the design of the device involved in the injury, the initial training of the injured party, and the design of the workstation, and continues up to the moment at which the event became unavoidable. Questions an interviewer might ask to obtain information related to this time period include:

Does the meat cutter have any formal food service training? Where did he receive it? When was the particular saw purchased and by whom? Had he ever used this kind of machine before? Had he ever been cut before?

When did the driver first receive his license? What driver training had he received? When did he first buy the car and from whom? What damage did it have at the time? Had it been involved in any prior collisions? What traffic controls were present? Were they functioning and visible?

How long had the secretary been using this chair? Was it a new chair or a replacement? How long had he been working at the particular company, or in this assignment or at this workstation? Had he ever noticed anything irregular about the chair or the floor? To whom did he report it, and when? Had he been injured previously? How did those prior injuries occur? What were the lighting conditions?

An example of pre-event information would be a reference to Ford's production of the Pinto in the 1970s. The Pinto developed a reputation for being involved in numerous fires upon rear-end collisions. During the ensuing litigation, it was found that certain design features might have contributed to the fires.

Of particular interest in automobile collisions are questions about prior collisions and damage, brake application prior to impact, distance moved by both vehicles as a result of the collision, and at-rest positions and separations of the involved vehicles. For all claimants interviewed, questions should be asked regarding factors present at least in the 24-hour period prior to the injury, including sleep patterns; drug and alcohol use, both prescription and recreational; interpersonal relationships; financial situation; and work conditions.

The incident period is that immediately following the point of no avoidance. That is, the moment at which the operator is committed to becoming involved in the event. For our injured meat cutter, it would be the time at which he no longer could pull his hand out of the path of the blade. For a driver of a vehicle, it is the time at which he no longer has the ability to avoid the collision by braking or turning. For our secretary, it is the time at which he began to sit in the chair.

The incident period continues until the event stabilizes: when the meat cutter has sustained the maximum injury, when all damage has occurred and the vehicles have come to rest, when the secretary is on the floor.

The post-incident period is the time from the end of the incident phase, and continues until the situation is completely returned to its pre-event condition. This includes medical treatment, litigation, vehicle repair, claimant retraining or rehabilitation, device redesign, or operator retraining. This time period could extend several years. In the event of a lifetime disability, it could continue for decades.

Questions pertaining to the post-incident period would include when medical treatment first was sought, where treatment was obtained, and who referred the claimant to the medical provider. Can the claimant describe the facility and the provider? When was treatment discontinued? Was he released, or did he stop on his own?

Together, these factors and time periods can be combined into a nine-cell accident investigation matrix, as seen in Figure 1. Dividing the incident into three time periods allows an interviewer to focus and organize his questions. Breaking down the causation factors and time periods enables the interviewer to conceptualize the factors that led up to the incident and its subsequent events.

The specifics of the interview are up to the imagination of the interviewer. The more inventive and inquisitive the interviewer becomes, the more information he will elicit. Use of the nine-cell matrix provides interviewers with a tool to organize interviews, efficiently categorize questions, and maximize the information obtained, while minimizing the time required to obtain the information. In any event, a thorough, in-depth interview can require an hour or more to conduct.

Organizing the interview keeps the information in an orderly format. Readers of the finished reports can find specific information quickly and decisions can be made more effectively. The interviewer is less likely to become sidetracked and omit relevant questions, and the time spent conducting the interview is reduced.

Richard Rinker is an investigator for MJM Investigations, based in Raleigh, N.C.