Definition
Mechanical latches that hold the landing gear securely in the retracted (up) position inside the wheel wells after retraction. They prevent the gear from falling out of the wells under its own weight, vibration, or aerodynamic loads, and must be released before the gear can extend.
Plain English
Small latches that grab and hold the landing gear in place once it has been pulled up into the airplane, so it stays tucked away until the pilot tells it to come back down.
Context Anchor
Seen in retractable-gear airplanes, especially when discussing abnormal or emergency landing gear extension.
Derivation
Up' refers to the retracted position of the gear; 'lock' is a holding device. Together: a lock that holds the gear up. Knowing this makes it clear why releasing the uplocks is the first step in any emergency extension — the gear cannot fall free until those latches let go.
Why Pilots Care
If the uplocks fail to release, the gear cannot extend normally and the pilot must use emergency methods to get the wheels down.
Intuition Check
Do not confuse gear uplocks with locks that hold the gear down for landing. Gear uplocks hold the landing gear up; they must release so the gear can extend.
Example Sentence 1
After the hydraulic pump failed, the pilot followed the emergency checklist to release the gear uplocks and let the wheels free-fall into position.
Example Sentence 2
When the normal hydraulic system failed, the pilot used the emergency handle to release the gear uplocks and let the gear drop.