Definition
Any landing gear behavior during extension or retraction that does not match the expected normal sequence or indication. This includes a gear that fails to retract, fails to extend, extends or retracts unevenly, gives no green light when down, shows an unsafe indication, or makes unusual sounds during the cycle.
Plain English
The landing gear is not doing what it should when the pilot raises or lowers it, or the cockpit indications do not confirm a normal, locked position.
Context Anchor
Encountered in retractable-gear airplanes, especially after takeoff when the pilot selects gear up and the gear does not retract or indicate normally.
Derivation
Abnormal comes from parts meaning “away from normal.” Operation means the way something works or is made to work. In this term, it means the landing gear system is working in a way that is away from the normal, expected procedure.
Why Pilots Care
Unresolved gear issues increase drag, reduce climb performance, and can create unsafe landing conditions.
Grounding Statement
If the pilot moves the gear handle and the airplane does not give the expected movement or safe indication, treat it as abnormal gear operation.
Intuition Check
Abnormal does not automatically mean the airplane is uncontrollable or that the pilot should improvise. It means the gear system is not behaving normally, so the pilot uses the published procedure and verifies the gear condition before continuing.
Example Sentence 1
Just after liftoff, the pilot selected gear up and noticed abnormal gear operation when the indicator lights did not show all three wheels stowed.
Example Sentence 2
The crew ran the abnormal gear operation checklist and attempted emergency extension before returning to land.