Annex 11 – Air Traffic Services


Developed by ICAO, the International Standards and Recommended Practices (SARPS) contained in the nineteen Technical Annexes to the Convention on International Civil Aviation (also called Chicago Convention) are applied universally and produce a high degree of technical uniformity which has enabled international civil aviation to develop in a safe, orderly and efficient manner.


Front page of Annex 11 - Air Traffic Services

Annex 11 to the Chicago Convention (titled: Air Traffic Services) deals with the establishment and operation of air traffic control, flight information and alerting services.


Established by the Provisional International Civil Aviation Organization (PICAO), the Rules of Air and Air Traffic Control (RAC) Division was responsible for the preparation of a text designed to replace the draft Annexes C (Rules of the air) and D (Air traffic control practices) to the Chicago Convention. Appropriate portions of the Annexes to the Paris Convention of 1919 published by the International Commission for Air Navigation - ICAN (in particular Annex D) were used.


The RAC Division held it first session (with 16 meetings) between 15 October and 19 November 1945 and made Recommendations for Standards, Practices and Procedures for Air Traffic Control. The revised text comprised: Standards particularly applicable to visual flight control (aerodrome traffic; type of control intervention when traffic becomes congested in a given area); Standards particularly applicable to instrument flight control (general traffic and aerodrome traffic); Standards for flight information service (list of signal standards necessary for the control of air traffic). Those Air Traffic Control Recommendations were reviewed by the PICAO Air Navigation Committee and approved by the PICAO Council on 25 February 1946 for use by Member States.


The second session of the RAC Division met from 3 December 1946 to 6 January 1947 and proposed Standards and Recommended Practices for Air Traffic Control. The Recommendations for Standards, Practices and Procedures on the Rules of the Air and Air Traffic Control and the Procedures for Air Navigation Services/Air Traffic Control were completely revised, and the Secretariat was directed to prepare an integrated document for circulation as an appendix to the Division's final report.


The Third Session of the RAC Division was held from 20 April to 10 May 1948. A plan was discussed and recommended for the preparation of Standards and Recommended Practices for the Establishment and the Operation of the Air Traffic Control Services. The Secretariat was entrusted with the actual preparation of these Standards along the lines described by the Division. A draft Annex (International Standards and Recommended Practices - Air Traffic Services) was prepared and thereafter submitted to States for comments. Annex 11 – Air Traffic Services was first adopted by the Council on 18 May 1950. The new title Air Traffic Services was preferred to the title Air Traffic Control, in order to make it clear that air traffic control service was a part of the services covered by Annex 11, together with Flight Information Service and Alerting Service.


Since the adoption of the first edition, Annex 11 has been continuously modified, adapted and expanded over the years further to recommendations issued by Divisional meetings, Air Navigation Conferences, the Air Navigation Commission (ANC), and various technical panels established by the ANC. The sky may be limitless but not for air traffic. As more aircraft fill the crowded air routes, air traffic control concepts, procedures, equipment and rules will continue to evolve as will the provisions of this Annex 11.


The provision of air traffic services is addressed in Annex 11 which provides that Contracting States shall determine, in accordance with the provisions of this Annex and for the territories over which they have jurisdiction, those portions of the airspace and those aerodromes where air traffic services will be provided. They shall thereafter arrange for such services to be established and provided in accordance with the provisions of this Annex, except that, by mutual agreement, a State may delegate to another State the responsibility for establishing and providing air traffic services in flight information regions, control areas or control zones extending over the territories of the former. The world's airspace is thus divided into a series of contiguous flight information regions (FIRs, or airspaces of defined dimensions) within which flight information service and alerting service are provided, and within which specific types of flights may operate and for which air traffic services and rules of operation are specified. ICAO’s provisions call for the establishment of flight information centres and air traffic control units.


Today, air traffic control, flight information and alerting services, which together comprise air traffic services, rank high among the indispensable ground support facilities, which ensure the safety and efficient operation of air traffic throughout the world. The objectives of the air traffic services are to:

a) Prevent collisions between aircraft;

b) Prevent collisions between aircraft on the manoeuvring area and obstructions on that area;

c) Expedite and maintain an orderly flow of air traffic;

d) Provide advice and information useful for the safe and efficient conduct of flights; and

e) Notify appropriate organizations regarding aircraft in need of search and rescue aid, and assist such organizations as required.



In the ICAO philatelic collection, it is the sole reference to an ICAO Flight Service Station (FSS).  A Flight Service Station is an air traffic facility that provides information and services to aircraft pilots before, during, and after flights, but unlike air traffic control, is not responsible for giving instructions or clearances or providing separation; the people who communicate with pilots from an FSS are referred to as specialists rather than controllers.

The precise services offered by flight service stations may vary by country, but typical FSS services may include providing pre-flight briefings including weather and notices to airmen (NOTAMs); filing, opening, and closing flight plans; monitoring navigation aids (NAVAIDs); collecting and disseminating pilots reports (PIREPs); offering traffic advisories to aircraft on the ground or in flight; relaying instructions or clearances from air traffic control; and providing assistance in an emergency. In many countries, flight service stations also operate at mandatory frequency airports to help co-ordinate traffic in the absence of air traffic controllers, and may take over a control tower frequency at a controlled airport when the tower is closed.

Recently, some countries, such as Canada and the United States, have been consolidating flight services into large regional centers. Until 1996, the Canadian federal government operated all air navigation services (FSS and air traffic control) through Transport Canada, a government department. Currently, a private non-profit corporation, NAV CANADA, operates both FSS and air traffic control, and has significantly modernized the system while at the same time, have replaced most local FSS with large centralized Flight Information Centers (FIC) as per Annex 11 , which provide the standard FSS services.

None FSS was ever established by ICAO. The one at Cambridge Bay, North West Territories (N.W.T.) may have been the result of cooperation between ICAO and Transport Canada to conduct tests using satellites in connection with search and rescue services. For years, Cambridge Bay airport has been a focus interest of mines. It is one of the most-northern airports in the world; yet, despite its remoteness, it is a relatively high-use resource, serving as a hub for access to the whole western side of northern Canada.