Definition
The height of the Minimum Descent Altitude (MDA) above the published airport elevation, expressed in feet. HAA is published on instrument approach charts for circling approaches.
Plain English
How many feet you are above the airport's elevation when you reach the lowest altitude you're allowed to fly down to on a circling approach.
Context Anchor
Seen in the landing minimums section of an instrument approach chart, especially with circling minimums.
Why Pilots Care
It sets the lowest safe altitude for circling the airport so the pilot maintains terrain clearance while maneuvering to the runway.
Grounding Statement
If the circling minimum puts you 600 feet above the airport elevation, the HAA is 600 feet.
Intuition Check
HAA does not mean your live height above the runway at every moment. It is a published chart value based on the circling minimum altitude compared with the airport elevation.
Example Sentence 1
The circling minimums on the chart showed an MDA of 1,340 feet and an HAA of 540 feet.
Example Sentence 2
With the airport at 400 feet elevation and a minimum descent altitude of 1100 feet, the resulting HAA is 700 feet.