What prodrome is typical before G-LOC?

• A. Gray-out or tunnel vision.
• B. Headache.
• C. Nausea.
• D. Dizziness only.

Answer: (A)

When the body undergoes high G-forces, cerebral blood flow drops. The earliest sign of this reduced perfusion is a visual warning: gray-out, where color vision is lost and vision becomes dull, often described as tunnel vision as the field of view narrows. This visual prodrome indicates that perfusion is dropping toward levels that could lead to G-LOC if forces continue or increase. Headache, nausea, or dizziness can occur in flight contexts but are not the classic, reliable warning signs for impending loss of consciousness. So gray-out or tunnel vision best represents the typical prodrome before G-LOC.