Radio communication failure occurs when an aircraft is unable to comply with the radio communication requirements outlined in SERA.8035, point (a).12 These procedures are critical emergency scenarios for pilots operating under Visual Flight Rules (VFR) or Instrument Flight Rules (IFR).2 Air traffic control units attempt to re-establish communication through other means, such as requesting assistance from other aircraft or units.3 As of May 1, 2025, new European Union (EU) procedures for radio communication failure introduce a second transponder code, 7601, for IFR flights in Visual Meteorological Conditions (VMC) that experience lost communications and decide to divert to the nearest suitable airport.4 In a radio failure in Instrument Meteorological Conditions (IMC), the pilot first maintains level and speed, then flies to the destination according to the flight plan, with an approach around the last expected approach time.56 Radiotelephony is the standardized voice communication between a pilot and air traffic control, designed for clear messages despite noise or accents.2 Communications also include datalink, which airline pilots use to interact with air traffic control and other aircraft.2

As of May 1, 2025, new procedures in European Union (EU) airspace include transponder code 7601 for IFR operations if the crew encounters visual conditions and chooses to continue visually.2

When an aircraft experiences radio communication failure, the flight crew must first attempt to establish contact on the previous channel used and, if unsuccessful, on another channel appropriate to the route.12 If initial attempts fail, the flight crew must try to establish communication with the appropriate air traffic services unit, other air traffic services units, or other aircraft using all available means, including data link, satellite voice, and mobile phones.12 When communication is successfully re-established, the flight crew must advise that contact on the assigned channel could not be made.1 For an IFR flight, if communication attempts are unsuccessful and the pilot-in-command decides to continue to fly in visual meteorological conditions, the pilot shall set Mode A Code 7601.1 A VFR flight experiencing radio communication failure must continue to fly in visual meteorological conditions, land at the nearest suitable aerodrome, and report its arrival by the most expeditious means to the appropriate air traffic services unit.1 New European Union (EU) radio communication failure (RCF) procedures will be implemented as of May 1, 2025.4 The UK Civil Aviation Authority (CAA) is not adopting certain new EU procedures for radio communication failure that took effect from May 1, 2025.2

Radio failure procedures are covered in the Communications section of CPL theory.5 The exam for the CPL tests the correct procedure for radio failure in IMC.5