Aircraft communications failure
When an aircraft station fails to establish contact with the aeronautical station on the designated frequency, it shall attempt to establish contact on another frequency appropriate to the route. If this attempt fails, the aircraft shall attempt to establish communication with other aircraft or other aeronautical stations on frequencies appropriate to the route.
If the attempts specified under 9.5.1 fail, the aircraft shall transmit its message twice on the designated frequency(ies), preceded by the phrase “TRANSMITTING BLIND” and, if necessary, include the addressee(s) for which the message is intended.
When an aircraft is unable to establish communication due to receiver failure, it shall transmit reports at the scheduled times, or positions, on the frequency in use, preceded by the phrase “TRANSMITTING BLIND DUE TO RECEIVER FAILURE”. The aircraft shall transmit the intended message, following this by a complete repetition. During this procedure, the aircraft shall also advise the time of its next intended transmission.
An aircraft which is provided with air traffic control or advisory service shall, in addition to complying with 9.5.3, transmit information regarding the intention of the pilot-in-command with respect to the continuation of the flight of the aircraft.
When an aircraft is unable to establish communication due to airborne equipment failure, it shall, if so equipped, select the appropriate SSR code to indicate radio failure (7600).
When an aeronautical station has been unable to establish contact with an aircraft after calls on the frequencies on which the aircraft is believed to be listening, it shall:
- request other aeronautical stations to render assistance by calling the aircraft and relaying traffic, if necessary; and/or
- request aircraft on the route to attempt to establish communication with the aircraft and relay messages, if necessary.
If the attempts specified in 9.5.6 fail, the aeronautical station should transmit messages addressed to the aircraft, other than messages containing air traffic control clearances, by blind transmission on the frequency(ies) on which the aircraft is believed to be listening.
Blind transmission of air traffic control clearances shall not be made to aircraft, except at the specific request of the originator.