What Is the Difference Between a Whiteout and a Blackout?
It is common to a see an inexperienced passenger losing consciousness as a jet pilot takes him or her through a series of aerial maneuvers that pull both positive and negative G's. Syncope or fainting is a temporary loss of consciousness where your skin becomes cold and clammy, you feel lightheaded or nauseous, and changes begin to occur in your field of vision. A whiteout or greyout is a transient loss of vision characterized by a perceived dimming of light and color. As a precursor to passing out, it is sometimes accompanied by a loss of peripheral vision and usually occurs much more slowly than a blackout.
Fainting or blackout usually happens when someone's blood pressure drops suddenly, which causes a decrease in blood flow to his or her brain. It can be caused by heat exhaustion, dehydration, emotional distress, standing up quickly, taking certain medications, heart problems or a sudden drop in blood pressure. Whiteouts due to cardiovascular changes are more common in aging adults and can often be reversed by having them sit down for moment to regroup. Whiteouts due to physical exertion most often subside after a few minutes of rest and recovery. Days that have a high "feels like" temperature are common culprits.
Fighter pilots experience more whiteout, blackout, greyout, and redout situations than the average person. However, auto accidents, amusement park rides, strenuous activities, medical conditons, prescription or over-the-counter drugs and certain occupations, create exposures for sudden changes to your vision. Fortunately, fighter pilots are trained to recognize the effects of G-force and use the changes in vision as an indicator that they are reaching maximum performance without losing consciousness. In general, a whiteout is produced by the opposite effect that causes a greyout and a redout out is the inverse of a blackout.
To experience a redout, the pilot must be inverted while exposed to G-forces, which can also happen in any vehicular accident on land, at sea or in the air. Unlike a blackout where the blood is forced away from the body, the inversion forces blood into the head, which is extremely uncomfortable and can result in bloodshot red eyeballs. Moreover, pulling positive Gs for a pilot is undesirable but pulling negative Gs is even more so. Redouts are potentially very dangerous and cause retinal damage or hemorrhagic stroke as well as damage from a redout-related crash. Surprisingly, during a whiteout or greyout, many people can still hear, speak and feel as the world continues to close around them.