Definition
The high-velocity, turbulent stream of air pushed rearward by a turning propeller. Prop wash extends behind the aircraft and can disturb people, equipment, loose objects, and other aircraft caught in its path.
Plain English
The strong blast of air a spinning propeller throws backward. It can be powerful enough to knock things over or rock a small aircraft sitting behind it.
Context Anchor
You encounter this on ramps, taxiways, run-up areas, and anywhere an aircraft is operating near people, other aircraft, or loose equipment.
Derivation
From propeller (the rotating blades that pull or push the aircraft through the air) and wash (a trailing flow of disturbed air or water, as in the wake behind a boat). Prop wash is literally the air the propeller leaves behind it.
Why Pilots Care
Prop wash affects ground handling, can blow loose objects or debris, and influences control surface effectiveness at low speeds.
Grounding Statement
Picture standing behind an airplane when the pilot adds power: the sudden hard wind you feel is propeller wash.
Intuition Check
Do not read “wash” as water or cleaning, and do not read “blast” as an explosion. In this term, both point to fast-moving air pushed by the propeller.
Example Sentence 1
Before adding power for the run-up, the pilot checked behind the aircraft to make sure prop wash would not blow debris toward the hangar.
Example Sentence 2
Strong prop blast from the idling engine moved loose items across the ramp.