Alerting Service

Alerting Service


A service provided to notify appropriate organizations regarding aircraft in need of search and rescue aid, and assist such organizations as required.

Source: ICAO Annex 11 - Air Traffic Services


Alerting service is part of air traffic service (ATS) and is therefore provided by ATS units (e.g. area control centres, flight information centres, etc.). The main task is to promptly notify the appropriate organizations (e.g. Search and Rescue (SAR) units) about the situation and provide relevant information about the aircraft in distress. The ATS units themselves do not provide SAR service.

Alerting service is provided to:

Information about aircraft in a state of emergency is normally collected by the relevant area control centre (ACC) or flight information centre (FIC). It is then forwarded to the appropriate rescue coordination centre. If the aircraft is under the control of an aerodrome control tower or an approach control unit, this unit would notify the appropriate ACC or FIC. Nevertheless, if required by the urgency of the situation, the aerodrome control tower or approach control unit would first alert all appropriate local rescue and emergency organizations able to provide immediate assistance.

If a flight operates through more than one FIR or control area, and its position is in doubt, responsibility for coordinating alerting service rests with the ATS unit of the FIR or control area:

  • within which the aircraft was flying at the time of last air-ground radio contact;
  • that the aircraft was about to enter when last air-ground contact was established at or close to the boundary of two FIRs or control areas;
  • within which the aircraft’s intermediate stop or final destination point is located:
    • if the aircraft was not equipped with suitable two-way radiocommunication equipment; or
    • was not under obligation to transmit position reports.

Notification Procedures

The ATS unit responsible for alering service:

  • Notifies the rescue coordination centre.
  • Notifies other units providing alerting services in other affected FIRs or control areas and requests their assistance.
  • Collects information, verifies it and forwards it to the rescue coordination centre.
  • Announces the termination of the state of emergency as circumstances dictate.

Rescue coordination centres are notified about:

  • Uncertainty phase when:
    • no communication has been received from an aircraft within a period of thirty minutes after the time a communication should have been received, or from the time an unsuccessful attempt to establish communication with such aircraft was first made, whichever is the earlier, or when
    • an aircraft fails to arrive within thirty minutes of the estimated time of arrival last notified to or estimated by air traffic services units, whichever is the later, except when no doubt exists as to the safety of the aircraft and its occupants.
  • Alert phase when:
    • following the uncertainty phase, subsequent attempts to establish communication with the aircraft or inquiries to other relevant sources have failed to reveal any news of the aircraft, or when
    • an aircraft has been cleared to land and fails to land within five minutes of the estimated time of landing and communication has not been re-established with the aircraft, or when
    • information has been received which indicates that the operating efficiency of the aircraft has been impaired, but not to the extent that a forced landing is likely, except when evidence exists that would allay apprehension as to the safety of the aircraft and its occupants, or when
    • an aircraft is known or believed to be the subject of unlawful interference.
  • Distress phase when:
    • following the alert phase, further unsuccessful attempts to establish communication with the aircraft and more widespread unsuccessful inquiries point to the probability that the aircraft is in distress, or when
    • the fuel on board is considered to be exhausted, or to be insufficient to enable the aircraft to reach safety, or when
    • information is received which indicates that the operating efficiency of the aircraft has been impaired to the extent that a forced landing is likely, or when
    • information is received or it is reasonably certain that the aircraft is about to make or has made a forced landing,

The above does not apply when there is reasonable certainty that the aircraft and its occupants are not threatened by grave and imminent danger and do not require immediate assistance.

All information given to the rescue coordination centre is normally communicated to the aircraft operator as well. If considered practicable by the ATS unit, the aircraft operator may be notified first.

Other aircraft in the vicinity of the emergency situation are also informed about it except in case of known or suspected act of unlawful interference. In such situations, the ATS unit would not refer to the nature of the emergency unless this is done by the aircraft involved and it is certain that doing so will not aggravate the situation.

Related Articles

Further Reading

  • ICAO Annex 11 - Air Traffic Services
  • ICAO Doc 4444 PANS-ATM, Chapter 9

SKYbrary Partners:

Safety knowledge contributed by: