Definition
The highest airspeed at which the landing gear may be safely extended (lowered) on a retractable-gear aircraft. Published in the Pilot's Operating Handbook and abbreviated VLO (extension).
Plain English
The fastest you can be flying when you put the wheels down without risking damage to the gear or the doors that cover it.
Context Anchor
Seen in the aircraft flight manual or pilot operating handbook, and used when setting the aircraft up before or during an instrument approach.
Derivation
Extension comes from the Latin idea of stretching or reaching out. In this term, it means the landing gear is moving out from the airplane and into the down position.
Why Pilots Care
Exceeding this speed while extending the gear can cause structural damage to the gear doors, actuators, or attachment points.
Intuition Check
Do not confuse maximum gear extension speed with the speed allowed after the gear is already down. This term is about the act of lowering the gear, when airflow loads on the moving parts can be high.
Example Sentence 1
She slowed to below the maximum gear extension speed before lowering the landing gear on the downwind leg.
Example Sentence 2
During an emergency descent the crew verified they were below maximum gear extension speed prior to manual gear deployment.