Definition
A visibility condition, usually associated with snow-covered terrain or low cloud over snow, in which the horizon disappears and surface features blend into a uniform white field, eliminating the visual references a pilot needs to judge attitude, altitude, and motion.
Plain English
Everything outside the airplane looks like one solid white sheet. The pilot can no longer tell where the ground is, where the sky is, or how the aircraft is moving in relation to them.
Context Anchor
Seen in attitude flying and visual-reference discussions, especially around snow-covered terrain, clouds, fog, haze, or low-contrast lighting.
Derivation
From 'white' plus 'out,' meaning the visual scene is washed out into a single white field. The word captures the experience directly: features are not just hidden, they are blanked out.
Why Pilots Care
Loss of the visual horizon forces an immediate transition to instrument references; failure to do so commonly leads to spatial disorientation or controlled flight into terrain.
Grounding Statement
Imagine flying over a snowfield on an overcast day -- the snow below and the cloud above are the same shade of white, and the line between them simply disappears.
Intuition Check
Whiteout does not just mean “heavy snow.” It means the normal visual cues are missing or unreliable because the outside scene has little or no contrast.
Example Sentence 1
The pilot encountered a whiteout while flying over the snow-covered plateau and immediately transitioned to the flight instruments to maintain attitude.
Example Sentence 2
During winter cross-country training, the instructor demonstrated how whiteouts remove every visual attitude cue the student had been using.