Redout is a visual phenomenon associated with negative G-forces where a person's visual field turns red as a result of a sudden rush of blood to the head. A classic example of a situation where this can occur is in stunt flying where a pilot takes a sudden steep dive, subjecting his body to negative G-forces. This can be very dangerous and pilots must take care to protect their bodies from acceleration stress. Positive G-forces, as when people climb and speed up suddenly, can cause the opposite problem, a flow of blood away from the head, leading to graying of the visual field, confusion, and other problems.