Characterization of the resulting incapacitation following unexpected +Gz-induced loss of consciousness.

+Gz-induced loss of consciousness (G-LOC) results in incapacitation which can be characterized by the unconscious period (absolute incapacitation) and a subsequent period of confusion/disorientation (relative incapacitation). The sum of the absolute and relative incapacitation periods represents the total incapacitation period and may be equated to the overall length of time a pilot would be in uncontrolled flight should G-LOC occur. Reviewing the centrifuge induced G-LOC episodes in 55 subjects allowed a detailed description of G-LOC. The absolute incapacitation period was 16.6 s with the subsequent relative incapacitation being 14.5 s resulting in an overall total incapacitation of 31 s. The G-LOC incapacitation was dependent on the rate of onset of the +Gz-stress and the +Gz level where G-LOC occurred. G-LOC episodes could be subdivided into 2 separate types: Type I being shorter unconsciousness episodes without convulsive movements, and Type II being longer unconsciousness with more frequently associated dream states and convulsive type movements. This detailed description of G-LOC allows a more complete understanding of the phenomenon and establishes the basis for research toward decreasing the resulting incapacitation from G-LOC. Minimizing G-LOC incapacitation and enhancing recovery should enhance safety in the aviation environment of the high-performance-fighter aircraft pilot.