Definition
The natural inclination of an aircraft to rotate left or right about its vertical axis as a result of aerodynamic and mechanical forces, particularly those produced by engine torque, propeller slipstream, P-factor, and gyroscopic effects in single-engine propeller aircraft.
Plain English
The aircraft's tendency to swing its nose left or right on its own, mostly caused by the engine and propeller, which the pilot has to correct with rudder.
Context Anchor
Pilots notice yawing tendency during takeoff, slow flight, climbs, stalls, and any maneuver where the airplane may not stay pointed where intended.
Derivation
Yaw' is an old nautical term meaning to deviate from a straight course, especially side-to-side. It carried over into aviation to describe rotation about the vertical axis. 'Tendency' simply means a natural pull in a particular direction. Together, the phrase describes the aircraft's built-in pull to swing off its heading.
Why Pilots Care
Uncorrected yawing tendency can lead to loss of directional control, especially during high-power, low-speed phases of flight.
Intuition Check
A yawing tendency is not the same as a full turn or a wing dropping. It is specifically the nose wanting to swing left or right.
Example Sentence 1
On takeoff, the student applied right rudder to counter the aircraft's left yawing tendency as power was added.
Example Sentence 2
An engine failure on a multi-engine airplane creates a strong yawing tendency toward the inoperative engine.