+Gz-induced loss of consciousness in undergraduate pilot training.

Class C physiologic incident reports during undergraduate pilot training (UPT) revealed that 1.7 episodes of G-induced loss of consciousness (LOC) occurred monthly in 1980-1984. The mean +Gz for the LOC episodes was +3.8 Gz; the minimum, +2.0 Gz. The mean time of total incapacitation was 12.0 s (maximum, 180.0 s) as subjectively estimated by the aircrew. Improper performance of the anti-G straining maneuver was the most common etiology of the LOC episodes. Symptoms associated with the LOC included complete unawareness of the episode, disorientation, confusion, tingling in the extremities, and flail-type movements of the extremities. The most common aerobatic maneuver causing LOC (30% of the episodes) was the split-S. Safety within the UPT program could potentially be enhanced by ensuring that instructor pilots know how to most efficiently perform the protective anti-G straining maneuvers and recognize the symptoms associated with G-induced LOC.