Operational G-induced loss of consciousness: something old; something new.
Loss of consciousness (LOC) during exposure to +Gz occurs in aircrew flying high-performance aircraft. This phenomenon is responsible for several USAF aircraft losses with accompanying loss of life. It has been recognized as a potential flying problem since 1938. Acceleration-induced LOC results in 15-to 20-s periods of aircrew total incapacitation, amnesia, and clonic spasms. It can occur at relatively low G levels and without symptoms of loss of light (blackout). Operational anti-G equipment and methods are not completely effective in preventing LOC. Considering the present status of G protection, a deficiency in the anti-G straining maneuver is considered to be the primary cause of G-induced LOC. This deficiency usually can be corrected with proper centrifuge training. Our present understanding of G protection suggests that the elimination of LOC as a serious problem for USAF high-performance aircraft operations must include the supination of aircrew to a minimum seat back angle of 60 degrees to 65 degrees.
D000054:Acceleration; D002560:Cerebrovascular Circulation; D006112:Gravitation; D006801:Humans; D002534:Hypoxia, Brain / Q000503:physiopathology; D009949:Orientation / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology; D013026:Space Flight; D014474:Unconsciousness / Q000503:physiopathology*