What effects are associated with +Gz acceleration?

+Gz acceleration refers to the forces exerted in a vertical direction, typically experienced during maneuvers such as pull-ups in flight. One of the most notable effects of +Gz is visual loss, commonly referred to as "grayout." As +Gz forces increase, blood is pulled toward the lower extremities, reducing the amount of blood—and consequently oxygen—that reaches the brain. This can cause a decrease in visual perception and may result in temporary loss of vision.

Grayout occurs before blackout, which is the complete loss of vision; thus, it serves as an early warning sign that the pilot is approaching a critical threshold of G-force. The condition is temporary, and recovery typically follows the removal of G-forces or a decrease in Gz.

Understanding the impact of +Gz acceleration is crucial for pilots, as they need to recognize these physiological limits and respond appropriately to maintain as much visual function as possible during high-stress maneuvers.