Definition
The loss of two-way radio communication between an aircraft and air traffic control (ATC). Under instrument flight rules (IFR), the pilot must follow specific lost communication procedures defined in 14 CFR 91.185, which prescribe the route to fly, the altitude to maintain, and when to begin the approach at the destination, depending on whether the aircraft is operating in visual or instrument meteorological conditions.
Plain English
When an aircraft and air traffic control can no longer talk to each other by radio, the pilot follows a set of pre-defined rules about where to fly, how high, and when to land — so that controllers can predict the aircraft's path even without being able to speak to the pilot.
Context Anchor
Seen in instrument procedure training and in real flight when radio contact with air traffic control is lost, unclear, or no longer dependable.
Derivation
Communication comes from a Latin word meaning “to share” or “make common.” Failure means something expected has stopped working. Together, the phrase means the normal sharing of flight information has broken down.
Why Pilots Care
It determines how the pilot maintains altitude, route, and approach clearance without ATC guidance, directly affecting traffic separation and safe arrival.
Grounding Statement
Picture flying in cloud on an assigned route and the radio goes silent; the pilot must continue in the way the rules say, not guess what the controller would have said next.
Intuition Check
Do not assume communication failure means only a completely dead radio. If the pilot and controller can no longer reliably exchange required information, it can be a communication failure.
Example Sentence 1
After losing both radios in cloud, the pilot squawked 7600, continued on the last assigned route, and flew the highest of the assigned, expected, or minimum IFR altitudes as required by the communication failure procedures.
Example Sentence 2
In communication failure during IFR, the pilot proceeds to the destination airport and lands within the expected arrival window.