Definition
A communication breakdown in which a pilot reads back an air traffic control clearance or instruction incorrectly, and the controller fails to detect the error and correct it, resulting in the pilot acting on a clearance that differs from what was issued.
Plain English
The pilot repeats the instruction back wrong, the controller doesn't catch the mistake, and the flight ends up doing something different from what was actually cleared.
Context Anchor
Encountered during radio calls with air traffic control, especially when copying altitude, heading, route, or approach instructions in instrument flight.
Derivation
Two words joined: 'readback' (the pilot reading the clearance back to the controller) and 'hearback' (the controller listening to that readback and confirming it matches what was issued). The slash signals that the error can occur on either side -- a wrong readback, a missed hearback, or both.
Why Pilots Care
Such errors can result in an aircraft climbing or descending to the wrong altitude or heading, reducing separation from other traffic or terrain.
Grounding Statement
This is a broken confirmation loop: the instruction given, the instruction repeated, and the instruction acted on do not all match.
Intuition Check
Do not think of this as only a pilot mistake. The full error includes both parts: the pilot’s readback is wrong or misunderstood, and the controller’s hearback does not catch it.
Example Sentence 1
The NTSB report identified a readback/hearback error as the cause of the altitude deviation, since the pilot read back 'climb to 11,000' instead of the assigned 10,000 and the controller did not catch it.
Example Sentence 2
During the climb clearance, the controller caught the readback/hearback error before the aircraft leveled at the wrong altitude.