Analysis of mission and aircraft factors in G-induced loss of consciousness in the USAF: 1982-2002

Previous studies have used questionnaires to evaluate G-LOC incident rates in different aircraft types, but no studies of G-LOC-related incident, crash, and fatality rates in different aircraft types were found in a search of the literature. G-LOC events (including both incidents and crashes) for the fiscal years 1982 to 2002 were obtained from the USAF Safety Center. Aircraft sortie numbers were obtained for all aircraft that had a G-LOC event reported. Contingency table analysis and Chi-squared tests were used to evaluate differences in G-LOC rates. Overall 559 G-LOC events occurred for a rate of 25.9 per million sorties (PMS), but event rates differed by almost two orders of magnitude between aircraft categories, being highest in basic training aircraft, intermediate in single crewmember fighters, and lowest in other aircraft types (p < 0.001). The proportion of events resulting in crashes was 30% in single-crewmember aircraft compared with 0.6% in trainers and other two-crewmember aircraft (p < 0.001). All of the crashes and fatalities occurred in aircraft occupied at the time by only a single crewmember. The crash fatality rate was 100% in attack aircraft, 73% in single-crewmember fighters, and zero in basic trainers (p < 0.05). The F-15 and F-16 aircraft did not have higher G-LOC rates than other single-seat fighters. The data suggest that both crew complement and mission play a role in determining G-LOC rates. The data also suggest that G-LOC in an aircraft with a ground attack mission is more likely to result in a fatality.