For other uses, see G-LOC (disambiguation).

g-induced Loss Of Consciousness is a condition where a person loses consciousness because g-forces move the blood away from the brain (black out) or move excess blood towards the brain (red out). The condition is most often linked to pilots of fighter planes or astronauts.

Incidents of acceleration-induced loss of consciousness were reported to have caused some deadly aircraft accidents in the 1970s. In the 1980s, in an attempt to reduce the risk of g-LOC related incidents, air force training facilities in many countries began to see centrifugation as a regular part of pilot training.

Aerobatic and fighter pilots may sometimes experience a brownout or grey out between 6 to 8g. This is not a total LOC but is characterised by temporary loss of coloured vision and/or tunnel vision, or even complete loss of vision temporarily, while consciousness remains. They may also be unable to interpret verbal commands.

See also

• G-suit
• brownout