Sending & hearing an urgency call
Sending: urgency signal ("PAN PAN") (RIC-21 7.1):
- Sent only on authority of person in charge of the station.
- May go to all stations or one station.
Frequency (RIC-21 7.3):
- First transmission on air-ground frequency in use.
- If communication cannot be established: repeat signal and message on 121.5 MHz (aeronautical emergency frequency), or any other available frequency.
Cancelling (RIC-21 7.5):
- Responsible station cancels an urgency message that called for action once no longer necessary.
- Addressed to ALL STATIONS.
Any station hearing the urgency signal (RIC-21 7.2):
- Keep listening on that frequency at least three minutes.
- Do not interfere with the message that follows.
- No urgency message within three minutes: notify an aeronautical ground station if possible. Normal working may resume.
- Station on a different frequency: may continue normal work, unless message addressed to all stations.
All-stations urgency message, once acknowledged (RIC-21 7.4): acknowledging station (another aircraft or aeronautical ground station) forwards urgency information to:
- ATS unit
- Airport operating agency, or its representative
Trap: urgency message goes to one station or all (RIC-21 7.1); cancellation always goes to ALL STATIONS (RIC-21 7.5). Three minutes is the least a station listens, not the most (RIC-21 7.2).
References
- RIC-21 7.1, 7.2, 7.3, 7.4, 7.5