Study the Legal Aspects of the use of GNSS for Air Navigation

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Study the Legal Aspects of the use of GNSS for Air Navigation

42ND ANNUAL CONFERENCE, Buenos Aires, Argentina, 17-21 March 2003

WP No. 169

Study the Legal Aspects of the use of GNSS for Air Navigation


The issue of legal aspects using the GNSS for air navigation was raised in the Taipei 1997 meeting (WP157) as an information material. The conclusion of the discussion as a result proposed two ways for ATCO’s to ensure safety management regulation and back up systems (or continuity of service provision).

Under the Chicago Convention (DOC 4444) and its annexes, there appears to be no legal obstacles either to the possibility of the provision of a supranational service by a single country or the provision by a supranational body or agency of a national service.

The legal aspects issue for the use GNSS for air navigation was raised again by EVP AFM to assist his Region.


ICAO Annex 11 states:

“ATS units shall be kept currently informed of the operational status of non-visual navigational aids, information on the operational status, and any changes therefore should be received by appropriate ATS unit on a timely basis consistent with the use of the aid(s) involved”.

When any failure to the GNSS occurs, it is to be expected that some aircrafts will fail to meet the RNP (Required Navigation Performance) and require special action to be taken, while others will be able to continue to meet the RNP. It is important that controllers and pilots are made aware of any degradation in a timely manner.

Any possibility of Jamming or any kind of interference, caused intentionally or accidentally by the provider or an additional third party, while an ATCO is in a process of maintaining any separation or other use of the system, not having the proper knowledge of the system’s operational status, or having no alert of it’s working mode (degraded or fault), could lead to a loss of separation or any incident / accident.

The above-mentioned should lead to a change in the navigational manner used by the pilot. The transfer to a ground based NAV aid, cancelling an consisted RNAV route, could lead to a loss of separation or any incident / accident.

IFATCA Technical policy is: (IFATCA Manual, p. 32111 “Display of GNSS status to ATC”)

“A monitoring and interpretation service should be established to monitor the status of all elements of the GNSS and interpret this information in a manner that provides relevant information to pilots and ATC. The information disseminated from the monitoring service or displayed at controller positions must be expressed in operational terms.

ATC procedures must be established for the use of GNSS and must cover the failure or degradation of the system. When ATC is informed of any change in the status of the GNSS (by monitoring or any display equipments), specific procedures associated with that change must be implemented. Should it not be possible to achieve the RNP in an airspace, an alternative RNP should be declared”.


IFATCA has legal policy on page 4413, stating under para 1.2.3 and 1.2.4 the following:

1.2.3. A controller shall not be held liable for any incident or accident resulting from the total or partial failure of any air traffic control system (Ottawa 94.C.29, amended Marrakech 00.C.11).

1.2.4. A controller shall not be held liable for incidents that may occur due to the use of inaccurate data if he is unable to check the integrity of the information received (Christchurch 93.C.22).


According to SC4, the wording “air traffic control system” in those policies cover the use of GNSS and any other CNS system. That is why this wording was used. Therefore SC4 is of the opinion that no additional policy should be made.


IFATCA requires that the safety, integrity, and reliability of GNSS be guaranteed before GNSS achieves the “sole means” status of navigation. An importance benefit of CNS is the declaration that GNSS becomes the “sole means” of navigation and communication, which will make the terrestrial NAV aids obsolete. Therefore, many of the existing ground aids could be removed eradicating the major costs of their maintenance and replacements.

The provision of Air Navigation is based on a case that such a service is provided by contract, the only way to counter or circumvent such inconvenience will be through the terms of the contract itself.

ICAO should represent the states that have signed the Chicago Convention, while on the other side contracting parties are the service providers (USA, Russia and Europe). All items dealing with service provision or any certification are beyond doubt, institutional issues that can be addressed by the contracting parties.


This paper be accepted as information.


Galileo: Global Satellite Navigation Services for Europe.

GNSS: by the European GNSS Office.

EEC 337: Report of the GNSS Frequency Protection requirements by the Eurocontrol Experimental Centre EEC.

Jane’s: Airport Review July/August 1999 Vol 11, Issue 6.

JAA: Position Paper on Navigation Augmentation Systems, 19.7.99, pp 008_4a.

CANSO: Report prepared by CNS/ATM Working Group Final Version June 99.

Policy: IFATCA Manual, IFATCA Technical Manual.

Last Update: September 29, 2020  

March 18, 2020   309   Jean-Francois Lepage    2003    

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