Absolute altitude is defined as?

• A. The actual distance between an aircraft and the terrain over which it is flying.
• B. The altitude above mean sea level.
• C. The altitude above ground level corrected for temperature.
• D. The maximum altitude authorized by air traffic control.

Answer: (D)

Absolute altitude is the height of the aircraft above the surface directly beneath it—the distance to the terrain over which you’re flying. This is why it changes with the terrain: you’re measuring how high you are relative to the ground below, not relative to sea level.

Altitude above mean sea level, by contrast, is a reference to height above the ocean surface and is the basis for true altitude calculations when determining clearance from obstacles and terrain over varying terrain. Temperature effects and corrections come into play with other concepts like density or true altitude, but they don’t redefine what absolute altitude measures. The maximum altitude authorized by air traffic control describes an assigned flight level, not the aircraft’s height above the terrain.