Definition
The full sequence of mechanical movement that occurs when retractable landing gear travels from the stowed (up) position to the fully extended and locked (down) position, including the operation of doors, actuators, locks, and indicator systems.
Plain English
The complete process of lowering the landing gear from up to down and locked, from start to finish.
Context Anchor
Seen during preflight and systems discussions for airplanes with retractable landing gear, especially when reviewing normal and emergency gear operation.
Derivation
From Latin extendere, 'to stretch out,' combined with 'cycle' from Greek kyklos, 'circle' or 'sequence of events.' Together it describes the full sequence of stretching the gear out from the airframe until it locks in place.
Why Pilots Care
A failed or slow extension cycle on takeoff or approach removes the pilot's ability to land with the gear down, creating an immediate emergency.
Intuition Check
Do not read cycle as only a time period. Here it means one complete landing gear movement from retracted to extended and locked.
Example Sentence 1
During the preflight briefing, the instructor explained that the normal extension cycle on this airplane takes about seven seconds from gear handle down to three green lights.
Example Sentence 2
If hydraulic pressure is low, the extension cycle may take longer or fail to reach the down-and-locked position.