Definition
An autopilot function that holds the aircraft at a selected pressure altitude without continuous pilot input, using altitude data from the air data system to command pitch corrections that keep the aircraft level at the chosen altitude.
Plain English
A setting that lets the autopilot lock onto an altitude and keep the aircraft there on its own, so the pilot does not have to hand-fly to maintain it.
Context Anchor
Seen in instrument flying, autopilot use, and altimeter system discussions where altitude information is used by aircraft equipment.
Derivation
Automatic comes from Greek roots meaning “self-acting.” Altitude comes from Latin altus, meaning “high.” Control means to regulate or keep something within limits. Together, the phrase points to a system that regulates aircraft height by itself after the pilot selects what it should hold.
Why Pilots Care
Reduces pilot workload during instrument flight by allowing sustained level flight without constant attention to the altimeter.
Analogy
It is similar to cruise control in a car, but for height instead of road speed. The driver still watches the road; the pilot still watches the altitude.
Intuition Check
Automatic does not mean the airplane decides what altitude is safe or legal. Here it means the system helps hold the altitude the pilot has selected or been assigned.
Example Sentence 1
Once established in cruise at 8,000 feet, she engaged automatic altitude control and turned her attention to the next waypoint.
Example Sentence 2
With automatic altitude control active, small pitch corrections kept the airplane level without the pilot touching the yoke.