Definition
An uncontrolled, rapid horizontal rotation of an aircraft about its vertical axis while on the ground, typically during landing rollout or taxi. It is most common in tailwheel (conventional gear) aircraft, where the center of gravity is behind the main wheels, making any sideways swerve tend to amplify rather than self-correct.
Plain English
The airplane suddenly spins sideways on the runway during landing or taxi, pivoting like a shopping cart whose back end has swung out in front of the front end.
Context Anchor
Seen in discussions of landing gear handling, takeoff rolls, and landing rollouts, especially when comparing tricycle landing gear with tailwheel landing gear.
Derivation
A combination of 'ground' (on the surface) and 'loop' (a circular or curving path). The term describes exactly what it looks like: the aircraft tracing a tight loop on the ground instead of continuing straight.
Why Pilots Care
Uncorrected ground looping can lead to runway departure, propeller damage, or gear collapse, especially in tailwheel aircraft.
Grounding Statement
On the runway, a small swerve can quickly become a sharp sideways turn if it is not corrected.
Intuition Check
Ground looping does not mean an aircraft makes an aerobatic loop. It means the aircraft turns sharply and uncontrollably while still on the ground.
Example Sentence 1
A gust of crosswind caught the tailwheel airplane during rollout, and the pilot had to act quickly with rudder and brake to prevent ground looping.
Example Sentence 2
Tricycle-gear airplanes resist ground looping better than tailwheel designs because the nosewheel provides greater directional stability.