Definition
An electronic circuit in a radio receiver that automatically keeps the audio output at a relatively constant level regardless of variations in the strength of the received signal. As the incoming signal grows stronger or weaker, the circuit adjusts the gain of the receiver's amplifier stages in the opposite direction, so the listener does not have to keep adjusting the volume knob.
Plain English
A built-in feature in a radio that automatically smooths out loud and quiet patches, so weak stations do not fade away and strong stations do not blast you.
Context Anchor
Seen in descriptions of aircraft communication and navigation radio receivers.
Derivation
Automatic, from Greek 'automatos' meaning self-acting. Volume here means loudness of sound. Control means to regulate. Together: a self-acting regulator of loudness.
Why Pilots Care
It prevents distracting volume changes during radio calls, allowing the pilot to focus on flying and listening without constant manual adjustments.
Analogy
It is like a helper quietly turning the volume knob up or down to keep the sound at about the same level.
Intuition Check
Do not read “control” here as only the cockpit volume knob. In this term, it means an internal radio function that adjusts the receiver automatically.
Example Sentence 1
The automatic volume control kept the tower's transmissions at a steady level even as the aircraft flew further from the airport.
Example Sentence 2
During preflight checks the pilot confirmed the automatic volume control was functioning by noting steady audio on weak test signals.