What is the most common cause of G-LOC?

The most common cause of G-induced Loss of Consciousness (G-LOC) is associated with improperly performed Anti-G Straining Maneuvers (AGSM). G-LOC occurs when the brain is deprived of adequate blood flow, often due to the high G-forces experienced during rapid acceleration in flight.

An effectively executed AGSM helps maintain blood flow to the brain by increasing systemic blood pressure and reducing pooling of blood in the lower extremities. If a pilot does not perform the AGSM correctly—such as not straining appropriately or failing to engage abdominal and leg muscles—the effectiveness of the maneuver diminishes. This can lead to a sudden decrease in cerebral perfusion and result in G-LOC, as the brain is sensitive to changes in blood flow.

Factors like hydration, excessive G exposure, and low oxygen levels can contribute to the risk of G-LOC, but an improperly executed AGSM is more directly linked to the immediate onset of this condition in high-G flight situations. Hence, understanding the importance of performing the AGSM correctly is crucial for pilots to prevent G-LOC during maneuvers that produce high G-forces.