Plain English Meaning
A coded holding pattern in the flight plan that keeps you circling the fix until the pilot decides — usually after an ATC clearance — to break out and continue.
Full Definition
An RNAV path-terminator leg that defines a holding pattern at a specified fix, which the aircraft continues to fly until the pilot manually terminates it, typically when cleared by ATC to leave the hold and proceed on course.
Context Anchor
Seen in instrument procedure coding and navigation-system behavior for RNAV procedures, especially where a published hold is part of an approach or missed approach path.
Derivation
The two-letter codes used for RNAV legs come from ARINC 424, the industry standard for coding navigation database paths. 'H' identifies the leg as a hold; the second letter says how the hold ends. 'M' stands for Manual — the pilot ends it by hand. Other hold codes use 'F' (single circuit, then continue) or 'A' (until reaching an altitude).
Why Pilots Care
Allows flexible delay or sequencing without a fixed time or distance limit, keeping the aircraft in protected airspace until cleared to proceed.
Grounding Statement
Picture the aircraft flying the racetrack-shaped hold repeatedly until the pilot tells the navigation system, “continue now.”
Intuition Check
Do not read “leg” as an ordinary body part; here it means one coded segment of a flight procedure. Do not assume an HM leg ends on its own; HM specifically means the pilot must manually terminate it.
Example Sentence 1
After the missed approach, the procedure coded an HM leg at the holding fix, so the crew remained in the hold until ATC cleared them for another approach.
Example Sentence 2
After entering the HM leg the crew remained in the hold until ATC issued further clearance.