Definition
A turn that develops on the ground without the pilot commanding it, occurring when directional control is lost during takeoff roll, landing rollout, or taxi. If allowed to progress, it can tighten into a ground loop — a rapid, unintended pivot of the airplane around its vertical axis.
Plain English
The airplane starts turning on its own while you're on the ground, against what you intended. You didn't ask for the turn; the airplane is doing it because something — usually crosswind, torque, or a swerve you didn't catch in time — is pulling it off the centerline.
Context Anchor
Seen in discussions of ground loops, especially with directional control during taxi, takeoff roll, and landing rollout.
Why Pilots Care
An uncontrolled turn can quickly escalate into a ground loop, damaging the wingtip, propeller, or landing gear and risking a runway excursion.
Grounding Statement
Picture the airplane rolling straight, then beginning to swing to one side faster than the pilot can keep it aligned with the runway.
Intuition Check
Do not read “uncontrolled turn” as just any turn the pilot did not plan. Here it means the airplane is turning in a way the pilot is not successfully controlling or correcting.
Example Sentence 1
A gust from the left started an uncontrolled turn during the landing rollout, and the pilot used right rudder and brake to straighten the airplane before it left the runway.
Example Sentence 2
A tailwheel airplane is especially prone to an uncontrolled turn if the pilot overcorrects with brake on a wet surface.