Definition
A communication failure between pilot and controller in which an incorrect clearance is either read back inaccurately by the pilot or read back correctly but not caught by the controller when listening to the readback. The result is that pilot and controller end up operating on different understandings of the same clearance.
Plain English
A mix-up between what the controller said, what the pilot repeated back, and what the controller heard. Either the pilot repeats it wrong, or the pilot repeats it right but the controller doesn't catch a mistake. Either way, the two end up disagreeing without realising it.
Context Anchor
Seen in radio communication with air traffic control, especially when receiving altitude, heading, route, speed, or approach clearances.
Derivation
Readback' is the pilot repeating the clearance back to the controller. 'Hearback' is the controller listening to that repeat to confirm it matches what was issued. An error in either step — speaking it wrong or hearing it wrong — produces the same dangerous result: a clearance that two people think they agree on but don't.
Why Pilots Care
These errors can result in flying the wrong altitude or route, creating conflicts with other traffic or terrain.
Grounding Statement
Picture a controller assigning 5,000 feet, the pilot mistakenly reading back 6,000 feet, and no one catching the mismatch before the aircraft climbs.
Intuition Check
This is not just a pilot mistake and not just a controller mistake. It describes a broken confirmation loop between the clearance, the pilot’s repeat, and the controller’s check of that repeat.
Example Sentence 1
The altitude bust was traced to a clearance readback/hearback error: the pilot read back 5,000 instead of the assigned 6,000, and the controller didn't catch it.
Example Sentence 2
The controller caught the hearback error when the pilot read back the wrong heading during the climb.