Injury data were obtained from the U.S. Army Safety Center for the occupants of U.S. Army aircraft who were both wearing aviator helmets and involved in duty-related aircraft accidents, for the period beginning on 1 January 1972 and ending 1 January 1983. The injury data were correlated with the physical condition of the involved helmets, examined by the authors under an Aviation Life Support Equipment Retrieval Program. Each helmet's performance was evaluated with regard to current injury prevention capabilities and potential improvements for future helmet design. For consistency, only the 208 SPH-4s in the data base were fully analyzed. Combat damaged helmets were excluded from this analysis.