The general purpose of studying accidents and forced landings is to improve air force effectiveness. Accident reduction must not be at the sacrifice of progress in the development and use of the most effective materiel; it must not prevent continual training and effective employment of personnel. Accident reduction must be an actual aid to both of these. The purpose of these studies is therefore to determine the laws of probability that govern the administrative, engineering, and operating phases, generally called "service conditions." In application, therefore, these studies become studies in management and are valuable aids in formulating both specific and general directives.