Definition
A visibility condition encountered over snow-covered terrain in which the pilot loses all sense of depth, distance, and horizon because uniform white snow on the ground blends with overcast sky, eliminating shadows, contrast, and visual reference points.
Plain English
Everything outside the aircraft looks like a featureless white blur. The pilot can't tell where the ground is, how far away things are, or where the horizon sits, because there is nothing dark or shadowed to judge against.
Context Anchor
Encountered in winter, mountain, Arctic, and snow-covered operations, especially when flying near the ground or trying to land.
Derivation
From 'white' plus 'out,' meaning a condition in which everything is washed out into white. The word mirrors 'blackout' in structure: a sensory loss caused by a single overwhelming condition.
Why Pilots Care
Loss of the horizon quickly leads to spatial disorientation; pilots must transition to instruments or risk controlled flight into terrain.
Grounding Statement
Imagine flying inside a ping-pong ball: the surface, the air, and the sky are all the same shade of white, with no edge, line, or shadow to tell you which way is up or how far away anything is.
Intuition Check
Whiteout does not always mean a blizzard or heavy falling snow. It means the pilot has lost useful outside visual cues because the scene has become mostly white and featureless.
Example Sentence 1
The pilot recognized whiteout conditions developing as the overcast thickened over the snowfield and immediately transitioned to instruments to maintain level flight.
Example Sentence 2
After takeoff in a light snow shower, whiteout developed and forced the crew to climb on instruments until they broke out above the clouds.