Definition
A path-terminator leg in an RNAV procedure that instructs the aircraft to fly a specified heading until the pilot manually terminates the leg, typically in response to an ATC instruction such as a radar vector or a clearance to intercept a course or fix. The leg has a defined heading but no defined endpoint in the navigation database; the flight management system continues the heading indefinitely until the pilot intervenes.
Plain English
A leg of a published procedure that tells you to fly a particular heading and keep flying it until you, the pilot, decide to end it — usually because ATC has told you to turn, climb, or join something else.
Context Anchor
Seen in instrument procedure coding and on some GPS or flight management system displays when a procedure uses a heading segment that must be ended by pilot action.
Derivation
In the ARINC 424 path-terminator coding system used by flight management systems, each leg is identified by a two-letter code. The first letter describes the path (V = heading, vector) and the second letter describes how the leg ends (M = manual termination). So 'VM' literally reads as 'heading, manually terminated.'
Why Pilots Care
The pilot must actively end the leg to continue to the next segment, which affects autopilot mode selection and procedure compliance.
Grounding Statement
Picture being told to fly heading 180 and keep flying it until ATC gives you the next instruction; that is the practical feel of a VM leg.
Intuition Check
Manual termination does not mean stopping the flight or shutting anything off. It means this procedure leg ends only when the pilot takes action or follows an instruction, not because the system reached a built-in endpoint.
Example Sentence 1
After takeoff, the SID called for a VM leg on a heading of 090, and we held that heading until departure control cleared us to join the airway.
Example Sentence 2
After manually terminating the VM leg the aircraft proceeded direct to the next fix.