Definition
The angle between an aircraft's longitudinal axis (nose-to-tail centerline) and the relative wind, measured in the horizontal plane. It indicates how much the aircraft is pointing to the left or right of the direction it is actually moving through the air.
Plain English
How far the nose is pointing sideways compared to the direction the aircraft is actually traveling through the air.
Context Anchor
Seen in aerodynamics and stability discussions, especially when an aircraft is not pointed exactly into the oncoming air.
Derivation
Yaw comes from an old nautical term meaning to swing or deviate from a straight course. A ship that yaws swings its bow off the line of travel. The aviation meaning carries this directly across: the aircraft's nose is swung off the direction of flight.
Why Pilots Care
Uncorrected yaw produces sideslip that increases drag, reduces climb performance, and can lead to loss of directional control in crosswinds or engine-out situations.
Grounding Statement
Picture the airplane moving forward through the air while its nose is slightly pointed to one side; that sideways difference is the angle of yaw.
Intuition Check
Angle of yaw is not the same as heading or bank. It is not simply where the nose points on the compass; it is how far the nose is pointed left or right compared with the oncoming air.
Example Sentence 1
During the crosswind landing, the pilot used rudder to reduce the angle of yaw just before touchdown so the wheels would track straight down the runway.
Example Sentence 2
During a crosswind landing the aircraft maintained a small angle of yaw to keep the fuselage aligned with the runway.