The human body has not evolved to meet the physical demands of flying a fighter jet. High G-forces, high altitude, low oxygen—the fighter jet places the human body in an environment and in situations far removed from what that body is built to withstand. Put simply, without specialized training and equipment, the environment is not compatible with life. This is why flying a fighter jet is among the most physically demanding and physically dangerous occupations in the world.  

The most obvious danger facing fighter pilots is exposure to G-force stress. When a jet is yanked or banked hard in a rapid maneuver, the pilot may experience up to nine times the force of gravity (9G), meaning, in that moment, the pilot’s body will feel as though it weighs nine times more than it does.........

© The National Interest