Definition
An HA leg is a path-and-terminator instrument procedure leg that defines a racetrack-shaped holding pattern flown until a specified altitude is reached. The aircraft continues circling in the published holding pattern until it climbs (or descends) to the altitude that ends the leg, at which point it exits and proceeds on the next leg of the procedure.
Plain English
It's a holding-pattern leg you keep flying around and around until you reach a certain altitude. Once you hit that altitude, you stop holding and continue with the rest of the procedure.
Context Anchor
Seen in area navigation instrument procedures and in discussions of path and terminator legs, where the procedure is built from coded segments the navigation system can follow.
Derivation
In the path-and-terminator coding system used by RNAV procedure designers, each leg type is given a two-letter code. 'H' indicates a holding-pattern path; the second letter indicates what ends (terminates) the leg. 'A' stands for Altitude. So 'HA' literally means 'hold until altitude.' Related codes include HF (hold to a fix) and HM (hold to a manual termination).
Why Pilots Care
An HA leg is commonly used when the aircraft needs extra room to climb to a safe altitude before proceeding on course, especially in mountainous terrain or after a missed approach. Leaving the hold early — before reaching the published altitude — can put the aircraft below obstacle clearance.
Intuition Check
Do not read “termination” as meaning the flight or procedure is over. Here it means this one coded leg ends when the aircraft reaches the specified altitude.
Example Sentence 1
After the missed approach, the procedure included an HA leg, so we kept circling in the hold until we reached 6,000 feet before continuing.
Example Sentence 2
After the missed approach, the HA leg keeps the aircraft in the racetrack until climbing through the published altitude.