Definition
An informal pilot term, spoken as 'wox-off,' for the worst possible weather conditions for flight: an indefinite ceiling at zero feet, sky obscured, visibility zero, and obscuration by fog. It comes from the old weather sequence report code 'W0X0F,' where W = indefinite ceiling, 0 = zero feet, X = sky obscured, 0 = zero visibility, and F = fog.
Plain English
Pilot slang for total fog — you can't see the sky, you can't see the ground, and you can't see anything in front of you. It means weather so bad that flying by visual reference is impossible.
Context Anchor
Seen in older aviation weather references, weather training, and discussions of extremely poor airport weather reports.
Derivation
Read directly from the old weather report code 'W0X0F.' Pilots pronounced the string of letters and zeros aloud as a single word — 'wox-off' — and it stuck as shorthand for 'as bad as weather gets.'
Why Pilots Care
Signals that visual flight is impossible and instrument procedures or delays are required.
Grounding Statement
Picture standing at the airport in thick fog with no view of the sky and no useful view down the runway.
Intuition Check
Woxof is not a cloud type or a forecast by itself. It is a coded way of saying zero ceiling and zero visibility in fog.
Example Sentence 1
The morning fog rolled in thick, and by 0600 the field was woxof — nobody was getting in or out.
Example Sentence 2
With WOXOF conditions at the destination, the tower advised us to expect a delay until the fog lifted.