Definition
A visibility condition in snow-covered terrain in which surface features and the horizon become indistinguishable because uniform snow on the ground combines with overcast or diffuse light to eliminate shadows, contrast, and depth perception. The pilot can still see, but cannot judge altitude, attitude, or the location of the surface.
Plain English
Everything outside the airplane looks like a blank white sheet. There is no horizon, no shadows, and no way to tell how high you are above the snow or where the ground actually is.
Context Anchor
Encountered during operations around snow-covered areas, especially during takeoff, landing, taxi, or low flight over snow when light is flat or snow is blowing.
Derivation
The term comes plainly from the visual effect itself -- the world appears uniformly white, with the sky and ground blending together into one indistinguishable field.
Why Pilots Care
Loss of visual references can cause spatial disorientation and lead to loss of aircraft control if the pilot continues flying by outside references.
Analogy
It is like trying to judge distance while looking at a plain white wall with no corners, shadows, or marks. Without features, your eyes have very little to measure against.
Grounding Statement
Imagine looking through the windshield and seeing only a soft, even white -- no ground, no sky, no line between them -- even though it is broad daylight and you are technically in clear air.
Intuition Check
Do not assume “white out” just means poor visibility from snow. The key danger is loss of visual references: the pilot may see white, but not enough detail to judge height, distance, or the horizon.
Example Sentence 1
The pilot aborted the approach when flat light over the snowfield produced a white out and the horizon disappeared.
Example Sentence 2
During the winter ditching drill the instructor emphasized that white out near the shoreline can hide the water surface until the last moment.