Definition
The natural tendency of an airplane on the ground to pivot into the wind around its vertical axis, caused by the wind striking the larger side surface area behind the main landing gear (such as the vertical stabilizer and rear fuselage) and pushing the tail downwind while the nose swings upwind.
Plain English
When an airplane is taxiing or rolling on the ground, a crosswind tries to swing its nose into the wind, like a weather vane on a barn rooftop turning to point into the breeze.
Context Anchor
Encountered during taxiing, especially when learning how to control the airplane in wind before takeoff or after landing.
Derivation
From 'weather vane,' the rooftop arrow that pivots to point into the wind. The airplane behaves the same way on the ground because more surface area sits behind its pivot point (the main wheels) than in front, so the wind pushes the tail around just like air pushes the tail of a weather vane.
Why Pilots Care
Uncorrected weathervaning can cause loss of directional control during taxi, leading to runway excursions or ground loops in tailwheel airplanes.
Grounding Statement
Picture wind from the right pushing the tail left; the nose swings right, toward the wind.
Intuition Check
Weathervaning tendency does not mean the airplane is simply being blown sideways. It means the airplane wants to turn so the nose points into the wind.
Example Sentence 1
During taxi in a strong left crosswind, the student felt the airplane's weathervaning tendency pulling the nose to the left and applied right rudder to stay on the centerline.
Example Sentence 2
The student pilot learned to anticipate the weathervaning tendency early in the takeoff roll and used appropriate rudder inputs to maintain directional control.