Definition
The act of repeating an air traffic control (ATC) clearance or instruction back to the controller, in full or in part, to confirm that it was received and understood correctly.
Plain English
When a controller gives you instructions on the radio, you say the important parts back to them so they know you heard it right. If you got something wrong, the controller can correct you before you act on it.
Context Anchor
Used in radio communication after a controller gives a clearance, altitude, heading, route, or other instruction that must be understood exactly.
Derivation
Plain English: 'read back' originally meant to read aloud something just received in writing. In radio work it carried over to repeating aloud what was just heard, so both sides can verify it matches.
Why Pilots Care
Accurate readbacks prevent miscommunication that could result in altitude deviations, airspace incursions, or loss of separation.
Intuition Check
Do not think of a readback as just acknowledging that you heard something. A readback means repeating the important words back so the controller can check them.
Example Sentence 1
After ATC issued the clearance, the pilot's readback included the assigned altitude, heading, and squawk code.
Example Sentence 2
During a busy approach, the controller requested readbacks of each new heading to ensure the instructions were copied correctly.