Definition
The turbulent, high-velocity stream of air pushed rearward by a spinning propeller. This airflow is faster, more disturbed, and often more turbulent than the surrounding air, and it can affect aircraft, people, and objects behind or near the propeller.
Plain English
The strong, churned-up wind blown backward by a spinning propeller.
Context Anchor
Encountered during engine start, run-up, taxi, parking, and any time an aircraft is operating near people or other aircraft on the ground.
Derivation
‘Prop’ is short for propeller. ‘Wash’ here means a disturbed flow of air or water left behind by something moving through it — the same sense as the ‘wash’ behind a boat. Together: the disturbed air left behind a propeller.
Why Pilots Care
Prop wash can blow debris, affect control surfaces on light aircraft, or create hazards for other planes and ground personnel during taxi or takeoff.
Grounding Statement
Behind a running propeller, the air can move with enough force to scatter loose items or disturb a nearby aircraft.
Intuition Check
“Wash” does not mean water or cleaning here. In this term, it means the disturbed air blown backward by the propeller.
Example Sentence 1
Before adding power for taxi, the pilot checked behind the aircraft to make sure no one was standing in the prop wash.
Example Sentence 2
During the preflight briefing the instructor reminded students to stay clear of the prop wash when walking around the airplane.