- W -

Warning: A signal which alerts the operator to a dangerous condition requiring immediate action; an instruction that is more critical than an advisory or a caution. May also indicate potential failure is eminent soon. 

Waypoint Approach: To approach a waypoint.

Waypoint: A point on the ground, predefined as a point of interest for the flight; a basic guidance mode, providing lateral guidance to a waypoint.

WCA: Warning- Caution- Advisory

Weight on Wheels (WOW): Indication of whether the aircraft has weight on its wheels, meaning airborne or on the ground; weight on wheels can be detected by a sensor on the wheels, computed from other state data or a combination of all data received.

Wheel: A flight control operated by turning with hands in fixed-wing aircraft, primarily to control roll (heading) via the ailerons; the wheel is connected to yoke.

Witness: One who testifies at a trial or a deposition.

Wrap test: A test to send data to a device having it sent back unaltered.