Definition
Physical locking devices fitted to an aircraft to deter unauthorized entry, movement, or operation while it is parked and unattended. Common forms include cabin door locks, ignition switch locks, propeller locks, throttle locks, and tow-bar or wheel locks.
Plain English
Locks installed on the airplane to stop someone from getting in, moving it, or starting it when the pilot is not there.
Context Anchor
Encountered during the engine shutdown and aircraft-securing steps, after the engine is stopped and before the pilot leaves the airplane parked.
Why Pilots Care
Proper use prevents aircraft theft, avoiding loss of the airplane and potential safety risks from unauthorized operation.
Intuition Check
Do not read this as only a cabin-door lock. In this context, it means the security lock devices used to secure that particular airplane after shutdown.
Example Sentence 1
After shutting down the engine and tying the airplane down, the pilot fitted the anti-theft security locks before walking back to the FBO.
Example Sentence 2
The securing checklist calls for fitting anti-theft security locks whenever the airplane will be parked unattended at the airport.