Primary research on the biomechanics of impact often informs accident investigation. Such research is the source of nearly all data on human injury tolerance, is the basis for the development of most biomechanical modeling techniques in common use, and provides crucial information on the performance of various occupant protection systems currently installed in vehicles. This paper utilizes a recent aviation accident study to highlight the ways that accident investigation contributes to, complements, and guides biomechanics research. Aside from the basic collection of epidemiological data on injury in vehicular crashes or other accident scenarios, accident investigation can provide detailed information regarding the effectiveness of injury countermeasures in real world situations, evidence of unintended consequences of such countermeasures, effects of population variation on injury causation, and assessment of actual (as opposed to nominal) use of various systems designed for end‐users, among other information. In addition, accidents may serve to highlight issues that might otherwise get little attention. While this attention may not directly drive primary research, it certainly provides an important input into vehicular design issues. Ultimately, the importance of accident investigation in biomechanics research may be to help focus the question of why the research is important in the first place.