Definition
An RNAV path-terminator leg that defines a holding pattern flown until the aircraft reaches a specified altitude. The aircraft remains in the holding pattern, flying laps, until the altitude condition is met, at which point it exits the hold and continues the procedure.
Plain English
A holding pattern that ends when you climb (or descend) to a specific altitude. You keep flying the racetrack pattern until you hit that altitude, then you exit and carry on with the procedure.
Context Anchor
Seen in instrument procedure design and flight management system coding, especially on departures or missed approaches that require holding until reaching an altitude.
Derivation
In the ARINC 424 path-terminator coding system, each leg type is identified by a two-letter code. The first letter describes the path; the second letter describes what ends (terminates) the leg. 'H' indicates a holding pattern path, and 'A' indicates the leg terminates at an Altitude.
Why Pilots Care
It guarantees the aircraft has climbed or descended to a safe altitude for obstacle clearance before proceeding to the next segment.
Grounding Statement
Picture the airplane flying a protected oval path until the altimeter shows the required altitude, then leaving the oval to continue the procedure.
Intuition Check
A leg is not a part of the airplane here; it is one segment of an instrument procedure. In an HA leg, the segment ends because an altitude is reached, not because a set number of holding turns has been flown.
Example Sentence 1
The missed approach procedure included an HA leg, so we entered the hold and continued climbing on each lap until we reached 5,000 feet, then proceeded on course.
Example Sentence 2
After the hold entry the aircraft remained in the HA leg until the altimeter showed the published altitude.