Definition
The exchange between pilot and air traffic controller in which the controller issues an instruction or clearance, the pilot reads it back to confirm understanding, and the controller verifies (or corrects) the readback. The loop is closed only when both parties agree on what was said.
Plain English
A back-and-forth between the pilot and controller that isn't finished until both sides are sure they heard the same thing. The controller says it, the pilot repeats it, and the controller confirms the repeat was correct.
Context Anchor
Seen in IFR clearance discussions, especially when a pilot receives a route, altitude, heading, or other instruction from air traffic control.
Derivation
A 'loop' is something that returns to where it started. Here, information leaves the controller, comes back through the pilot's readback, and returns to the controller for confirmation -- closing the circle.
Why Pilots Care
Closing the loop prevents the pilot from flying the wrong altitude, route, or heading and gives the controller immediate confirmation that the clearance is understood.
Intuition Check
Do not assume a communication loop means simply talking on the radio. In this context, the loop is complete only when the important message has been confirmed or corrected.
Example Sentence 1
After receiving the descent clearance, the pilot read it back fully, and the controller's 'readback correct' closed the communication loop.
Example Sentence 2
After the tower issued the takeoff clearance the student pilot completed the communication loop by repeating the runway and departure instructions.