Definition
Wedge-shaped blocks placed snugly against the front and back of an aircraft's tires to prevent the airplane from rolling when parked. Typically used in pairs on at least one wheel, often the nose or main gear, and removed before taxi.
Plain English
Small angled blocks set against the tires to stop the airplane from rolling while it's parked.
Context Anchor
You will encounter chocks during parking, engine start, engine shutdown, and ramp procedures.
Derivation
From the older English word 'chock,' meaning a wedge or block used to steady or prevent movement of something. Same idea as a doorstop — a small wedge that holds a much larger object in place.
Why Pilots Care
Prevents the aircraft from rolling and causing damage or injury during engine operations or while unattended on the ramp.
Grounding Statement
Picture a small wedge pressed against a tire so the wheel cannot start rolling.
Intuition Check
Chocks are not the same as parking brakes or tie-downs. They are physical blocks at the wheels, and they only work when placed firmly in the right position.
Example Sentence 1
After engine shutdown, the pilot set the parking brake and signaled the lineman to place the chocks.
Example Sentence 2
After the preflight, the ramp crew pulled the chocks so the airplane could taxi.