Definition
The vertical distance, expressed in feet, between the Minimum Descent Altitude (MDA) on a circling instrument approach and the published airport elevation. HAA is published on instrument approach charts for circling minimums.
Plain English
How high above the airport you are when you reach the lowest altitude allowed during a circling approach. It tells you, in feet, how far above the airport the bottom of your descent sits.
Context Anchor
Seen in the minimums area of instrument approach information, including radar approach examples, especially where circling minimums are shown.
Derivation
Reads literally as 'Height Above Airport.' The key word is 'airport' — the reference is the published airport elevation, not the runway, not the terrain, not sea level. That choice of reference is what distinguishes HAA from similar values like HAT (Height Above Touchdown).
Why Pilots Care
Maintains required obstacle clearance while maneuvering to land in low visibility.
Intuition Check
Do not read HAA as the altitude to set or fly by itself. It is a height difference: published circling minimum altitude minus airport elevation.
Example Sentence 1
The circling minimums for this approach show an MDA of 1,340 feet and an HAA of 543 feet.
Example Sentence 2
Radar vectors placed the aircraft at the minimum HAA for the airport elevation.