From SKYbrary Wiki
The force or wind generated behind a propellor, particularly on or before take-off when high/full power is set, but also when the aircraft is taxiing.
Prop Wash Prop Wash can be hazardous to other aircraft, particularly light aircraft, and people in the vicinity of the aircraft and can cause damage to equipment, buildings, and pavement surfaces.
Turbojet engines, especially on large transport aircraft, can produce even more significant winds behind them when operating at high power. this phenomenon is known as "Jet Efflux Hazard"
For further information, see the larger article "Jet Efflux Hazard"
- "Applying Take-off Thrust On Unsuitable Pavement Surface May Have Hidden Dangers", by Bertrand de Courville & Jean-Jacques Thisselin, Air France, ICAO Journal, No.3, 2004.