Definition
Rotation of the airplane's nose to the left around its vertical axis. In single-engine propeller airplanes, left yaw is the natural tendency caused by the combined left-turning forces (torque, P-factor, spiraling slipstream, and gyroscopic precession) that become most pronounced at high power settings and high angles of attack, such as during slow flight, takeoff, and climb.
Plain English
The nose of the airplane swings to the left. In most propeller airplanes, this happens on its own when power is high and speed is low, and the pilot has to use right rudder to keep the nose straight.
Context Anchor
Seen during slow flight practice when the airplane is flying slowly with higher power and the pilot is watching for nose movement that needs correction.
Derivation
Yaw is an old nautical term meaning to swing or deviate off course. Pilots borrowed it from sailing, where a ship that 'yawed' was twisting side-to-side around its vertical axis. 'Left' simply tells you which direction the nose is swinging.
Why Pilots Care
Uncorrected left yaw produces uncoordinated flight, extra drag, and a higher stall or spin risk during slow flight.
Intuition Check
Left yaw is not the same as a left bank or a complete left turn. It means the nose is swinging left around the airplane’s up-and-down axis.
Example Sentence 1
As the student reduced airspeed and added power to maintain altitude in slow flight, the nose began a noticeable left yaw, which she corrected with steady right rudder pressure.
Example Sentence 2
A sudden reduction in power can create right yaw, while high power settings commonly create left yaw that must be countered with rudder.