FAA Ground School Practice Test

What is absolute altitude?

1. The altitude above mean sea level

2. The altitude indicated when the barometric pressure scale is set to 29.92

3. The vertical distance of the aircraft above the surface

4. The vertical distance of the aircraft above the water level

The correct answer is: The vertical distance of the aircraft above the surface

Absolute altitude refers to the vertical distance of the aircraft above the ground level directly beneath it. This measurement is crucial for various aviation operations, such as determining safe clearance over terrain, managing obstacles, and ensuring proper altitude separation from the ground. Absolute altitude can change even when the aircraft's altitude above sea level remains constant, particularly in hilly or mountainous terrain. The distinction between absolute altitude and other altitude measures, such as indicated or pressure altitude, helps pilots understand their aircraft's height relative to varying surfaces, which is critical for safety. While mean sea level provides a standard reference point, absolute altitude gives a real-time perspective of an aircraft's position in relation to the ground, which is particularly important during takeoffs, landings, and low-altitude maneuvers.