Communication

The following procedure is based on ICAO Doc 7030 – European Region guidelines for communication failure in IMC under radar control:

1. Attempt all possible means of communication, including alternate frequencies and 121.5 MHz.
   If unsuccessful, squawk 7600 and begin timing:

   • 7 minutes if under radar control
   • 20 minutes if outside radar coverage

2. Transmit blind on the last assigned frequency, using the phrase:

   • “TRANSMITTING BLIND” (repeat the message twice)
     If you believe your transmissions are working but you cannot receive, use:
   • “TRANSMITTING BLIND DUE TO RECEIVER FAILURE“

3. Maintain the last assigned speed and level, or the Minimum Safe Altitude (MSA), whichever is higher, for:

   • 7 minutes (under radar), or
   • 20 minutes (outside radar)

4. If failure occurred while being vectored, rejoin the flight-planned route while maintaining terrain clearance (e.g. using MORA).

5. After the required time has passed, resume the filed flight plan, including speed and altitude.

6. Proceed to an appropriate fix for approach (e.g. the Initial Approach Fix), and enter the holding pattern.

7. Initiate descent:

   • At the Expected Approach Time (EAT) if issued by ATC, or
   • At the Estimated Time of Arrival (ETA) if no EAT was given

8. Land within 30 minutes of the EAT or ETA, whichever applies.

Note: Always check for airport-specific communication failure procedures, which take precedence over the general rules above.

ADS-C stands for Automatic Dependent Surveillance – Contract.

It is a type of position reporting system used in remote and oceanic airspace where radar and real-time surveillance are not available. Unlike ADS-B, ADS-C transmits data only when requested, based on a contract between the aircraft and the ground station.

How it works

• A contract is established between the aircraft and ATC (typically via CPDLC).
• The aircraft automatically sends position reports based on:
  • Time intervals (periodic contract)
  • Waypoints crossed or other event (event contract)
  • Request from ATC (demand contract)

What data is transmitted

• Current position (latitude, longitude, altitude)
• Time of position report
• Estimated time and position at next waypoint
• Navigation intent information (e.g. route and flight plan data)

Benefits of ADS-C

• Enables ATC surveillance in non-radar areas such as the NAT HLA, Pacific, and Indian Ocean FIRs
• Supports reduced separation minima when combined with RNP-capable systems
• Provides reliable position monitoring in remote environments

Note: ADS-C is a key component of FANS (Future Air Navigation Systems) and works in conjunction with CPDLC to improve communication and surveillance beyond radar coverage.

The correct phraseology to cancel a distress condition is:

“[CALLSIGN], CANCEL DISTRESS”

This message must be transmitted as soon as it is confirmed that the aircraft and its occupants are no longer in danger and the emergency has been resolved.

Note: ATC will then terminate any emergency handling procedures and resume normal operations with the aircraft.
Source: ICAO Doc 9432 — Manual of Radiotelephony.