A New Model of how People Investigate Incidents

Abstract

We used a simulation methodology to provide a direct measurement of how incidents and accidents are investigated. Thirty-seven aviation maintenance personnel with incident investigation experience investigated are six incident scenarios that we developed from actual maintenance incidents. Using a methodology developed by Woodcock and Smiley (1999), participants were given a brief incident description and had to question the experimenter to determine how the incident happened. We counted the number and types of information requests, and recorded their sequence. Based on the sequence data we propose a five-stage model of incident investigation. An initial trigger initiates an interactive data collection/data analysis period, starting by determining spatial and temporal boundaries then investigating in a somewhat sequential manner. A stopping rule is used to determine when to stop investigating and begin the final reporting stage. The number of facts considered grows during the investigation stage, but then decreases at the reporting stage. Thus, basing recommendations on the reports of incidents may not consider all causal factors.