Summary

This paper introduces the Global Aeronautical Distress and Safety System (GADSS). The system sees aircraft operators tracking their aircraft separately from the ATC system in certain circumstances and introduces new supporting infrastructure and procedures. Provisions for GADSS are contained Annex 6 to the Convention and became effective in 2018 for normal tracking; tracking of aircraft in distress will be required from 2021.

Introduction

1.1  After the crash of Air France flight 447 and the disappearance of Malaysia Airlines flight 370, ICAO began working on a global framework for tracking commercial aircraft.

1.2  A plan was developed for the short-, medium- and long-term to develop a system for operators to track their own aircraft; some changes have already occurred and more will occur in the future. While the procedures are intended to be invisible to controllers as much as possible, there may still be some changes visible to controllers.

Discussion

2.1  Normal tracking

2.1.1  Global procedures for the tracking of aircraft were included in Annex 6 to the Convention on International Civil Aviation and became effective in 2018. Annex 6 now demands that commercial aircraft operators establish a capability to track their aircraft. It is important to note that normal tracking is an operator responsibility that does not change the roles or responsibilities of controllers.

2.1.2  Annex 6 recommends that the operator should track the position of certain aircraft through automated reporting at least every 15 minutes. This recommendation only applies:

a) for aircraft with MTOW >27,000 kg and with >19 seats; and

b) when the ATS unit does not obtain their own position information at least every 15 minutes.

2.1.3  Annex 6 requires that the operator shall track the position of certain other aircraft through automated reporting at least every 15 minutes when in oceanic areas. This recommendation only applies:

a) for aircraft with MTOW >45,000 kg and with >19 seats; and

b) when the ATS unit does not obtain their own position information at least every 15 minutes.

2.1.4  The following diagram demonstrates the normal tracking requirements for some aircraft that are applicable today.

2.1.5  The operator will collect the position information of its aircraft participating in normal tracking and will be able to provide this information to search and rescue (SAR) authorities on request.

2.2  Distress tracking

2.2.1  Distress tracking is a process of receiving and sharing the position of an aircraft in distress. Equipment for distress tracking will only be required for aircraft with MTOW >27,000 kg manufactured after on or after 1 January 2021. The equipment is also recommended for aircraft with MTOW >5,700 kg manufactured from the same date. The ICAO provisions are performance-based i.e. they do not specify a particular type of technology, just the level of performance that the technology must meet.

2.2.2  What is meant by distress? According to ICAO:

(ICAO. (2018). p. APP 9-1)

2.2.3  When an aircraft is equipped for distress tracking, the equipment will activate automatically upon detection of unusual or dangerous behaviour e.g. unusual attitudes or speeds (although it will also have a manual activation function). The activation of distress tracking will occur regardless of whether or not the aircraft is participating in normal tracking at the time. Distress tracking equipment will broadcast the position of the aircraft at least once every one minute.

2.2.4  When distress tracking is activated, the operator will be automatically notified. Annex 6 requires that the operator notifies the appropriate ATS unit if they are aware that one of their aircraft is in distress. Annex 6 also requires that an ATS unit that becomes aware of an aircraft in distress notifies the operator of the aircraft.

2.2.5  When distress tracking is activated, the aircraft’s position information will be uploaded to the aircraft distress tracking data repository.

2.3  Locating

2.3.1  By broadcasting aircraft position at least every one minute, distress tracking is intended to allow for the location of an accident site to be determined to within 6 NM.

2.3.2  The accurate position information of aircraft in distress will be uploaded to an aircraft distress tracking repository, to which SAR authorities will have access, aiding in the effectiveness of rescue and recovery efforts.

2.4  What changes for ATC

2.4.1  The Annex 6 procedures are intended to have minimal effect for ATC; however, there may be changes in the way that information is obtained.

2.4.2  During normal tracking, operators should have robust systems and procedures in place for obtaining position information from their aircraft. While operators have the contact details of ATS units, which they may use if they are unable to locate one of their aircraft subject to normal tracking, IFATCA has made its position clear during the development of these procedures that while controllers are ready to help, normal tracking is an operator responsibility. It is expected that normal tracking systems will be sufficiently reliable to see few calls to ATS units.

2.4.3  When distress tracking is activated, the operator will be automatically notified and they must then notify ATC. There are no changes to Annex 11 provisions for the alerting service provided by ATC. Should an operator be unable to contact their aircraft, or should they be aware that their aircraft is in distress, they will contact the ATS unit, which may be a prompt for the controller to commence communication checks or it may confirm a loss of communication or state of emergency. Regardless of whether an aircraft’s state of emergency is discovered through an operator or by their own means, controllers should continue to follow existing alerting service procedures.

Conclusion

3.1  Annex 6 was updated in 2018 to include procedures for normal and distress tracking. While normal tracking commenced in 2018, distress tracking is only mandated for aircraft with MTOW >27,000 kg manufactured on or after 1 January 2021.

3.2  Normal tracking consists of operators obtaining position reports from their aircraft at least every 15 minutes except when the ATS unit does this anyway e.g. using surveillance or data link. Normal tracking is an operator responsibility that does not change existing ATC roles or responsibilities.

3.3  Distress tracking will activate automatically upon the detection of unusual and dangerous aircraft behaviour e.g. unusual attitudes or speeds. An aircraft will broadcast its position at least every one minute when it is in distress and this information will be made available to the appropriate SAR authorities, which should allow for the location of any accident site to be known to within 6 NM and aid the search and recovery activities.

3.4  There should be minimal effect on ATC of the new procedures. Operators are required to notify the appropriate ATS unit when they become aware than one of their aircraft is in distress and this may prompt communication checks with the aircraft or it may confirm information that the controller already had. Regardless, controllers should continue to follow existing alerting service procedures.

References

ICAO. (2018). Annex 6 to the Convention on International Civil Aviation: Operation of aircraft: Part I – International commercial air transport – Aeroplanes, 11th ed., ICAO: Montréal, Canada.