Height Above Touchdown is measured using which reference?

Height Above Touchdown is measured using which reference?

• A. Above Ground Level
• B. Mean Sea Level
• C. Pressure Altitude
• D. Above Mean Sea Level

Answer: (A)

Height Above Touchdown uses the actual surface at the touchdown point as the reference, so it is measured as Above Ground Level. This means the vertical distance is how high you are above the ground right where you would touch down, not above sea level or a standard pressure datum. Mean Sea Level would reference sea level regardless of terrain, and pressure altitude is a standardized altitude based on pressure, not the landing surface. In practice, your height above touchdown equals your current altitude above mean sea level minus the runway surface elevation, so it varies with terrain and runway height. For example, if the runway sits at 6,000 ft MSL and you’re 7,000 ft MSL above the same point, your height above touchdown is 1,000 ft, i.e., 1,000 ft Above Ground Level.

Height Above Touchdown uses the actual surface at the touchdown point as the reference, so it is measured as Above Ground Level. This means the vertical distance is how high you are above the ground right where you would touch down, not above sea level or a standard pressure datum. Mean Sea Level would reference sea level regardless of terrain, and pressure altitude is a standardized altitude based on pressure, not the landing surface. In practice, your height above touchdown equals your current altitude above mean sea level minus the runway surface elevation, so it varies with terrain and runway height. For example, if the runway sits at 6,000 ft MSL and you’re 7,000 ft MSL above the same point, your height above touchdown is 1,000 ft, i.e., 1,000 ft Above Ground Level.