Definition
A wedge-shaped block, typically made of wood, rubber, or hard plastic, placed snugly against the front and rear of an aircraft tire to prevent the aircraft from rolling while parked.
Plain English
A small block placed against a wheel to stop the aircraft from rolling when it's parked.
Context Anchor
Seen during parking, preflight, ramp operations, engine run-up preparation, and aircraft servicing.
Derivation
From the Old French 'choque,' meaning a block or stump of wood. The aviation use carries the same idea straight across: a solid block wedged in place to stop something from moving.
Why Pilots Care
Prevents unintended aircraft movement that could cause damage to the plane, nearby equipment, or injury to people on the ground.
Intuition Check
Do not think of a chock as part of the airplane’s braking system. A chock is a separate physical block placed at the wheel to keep the aircraft from moving.
Example Sentence 1
Before shutting down, the pilot signaled the line crew to place chocks at the main wheels.
Example Sentence 2
Before starting the engine, the pilot confirmed that all chocks had been removed from the main landing gear.