What does HAT stand for in aviation terminology?

• A. Height Above Touchdown Elevation
• B. Height Above Airport
• C. Height Above Terrain
• D. Height Above Landing

Answer: (A)

Height Above Touchdown Elevation is the vertical distance from the airplane to the touchdown elevation of the runway. The touchdown zone surface has a fixed elevation, and HAT expresses how far your current altitude is above that specific point on the runway where you will touch down. This reference is used on instrument approach charts to represent how high you are above the actual landing surface, helping you gauge descent and ensure obstacle clearance as you near the runway. For example, if the touchdown zone elevation is 800 feet and you’re at 1,200 feet, your height above touchdown elevation is 400 feet. This concept is tied to the touchdown point, not the overall airport elevation or terrain ahead, which is why the other terms don’t fit standard aviation usage.