Definition
The vertical distance of an aircraft above the terrain directly beneath it, expressed in feet above ground level (AGL).
Plain English
How high you are above the ground right below you, right now.
Context Anchor
Seen in discussions of terrain clearance, low-level flight, and instruments that measure height above the surface below the aircraft.
Derivation
In everyday speech, 'absolute' often means 'perfect' or 'total.' Here it carries its older sense of 'measured from a fixed reference' — in this case, the ground directly below the aircraft, rather than sea level or another aircraft.
Why Pilots Care
Knowing absolute altitude prevents controlled flight into terrain during low-level or instrument operations.
Grounding Statement
A radar altimeter shows the pilot this exact distance to the ground below.
Intuition Check
Absolute does not mean perfect here. It means measured from the surface directly below the aircraft, not from sea level.
Example Sentence 1
Flying over rising terrain, the pilot's absolute altitude decreased even though the altimeter reading stayed the same.
Example Sentence 2
Absolute altitude readings help maintain safe clearance during night approaches to unfamiliar airports.