A pilot's g-suit is a one-piece jumpsuit that protects
him from losing consciousness as blood drains away from his head.
A fighter pilot coming out of a dive can experience up to nine
g's. The g-suit puts pressure on the pilot's abdomen and legs
to keep blood from accumulating in those areas and starving his
brain. It works; an unprotected person can lose consciousness
at even two g's.
The reverse affect, is more
dangerous. Even three negative g's will drive blood to the retina
and cause red out. If a pilot must go into a very steep
dive at speed they roll the plane over first to avoid negative
g's.