Which is NOT a typical sign of G-LOC or high-G intolerance?

• A. Graying out or tunnel vision, dizziness, confusion, and loss of consciousness
• B. Drowsiness during flight
• C. Shortness of breath during high-G
• D. Headache that persists after regaining normal blood flow

Answer: (D)

When high-G affects the brain, the defining signs come from the rapid drop in cerebral blood flow. The most typical manifestations are visual changes from reduced cranial perfusion—graying out or tunnel vision—along with dizziness, confusion, and, in some cases, loss of consciousness. These reflect the brain not getting enough blood during the exposure.

Drowsiness during flight is a non-specific symptom that can occur for many reasons (fatigue, cabin conditions, dehydration) and isn’t a distinctive sign of G-LOC itself. Shortness of breath during high-G isn’t a direct hallmark of G-LOC either; it points more to respiratory or cardiovascular strain rather than the transient cerebral hypoperfusion at the heart of G-LOC.

A headache that persists after normal blood flow is restored isn’t typical of G-LOC or high-G intolerance. If a headache lasts after perfusion returns to normal, it suggests another issue beyond the immediate high-G event, rather than a classic sign of G-LOC.