LOCATION INDICATORS INDICATEURS D'EMPLACEMENT ...

FOREWORD
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This document contains a list of ICAO four-letter location indicators and, for ease of reference, corresponding three-character
International Air Transport Association (IATA) location identifier codes for geographical locations throughout the world. Also
included is a list of addresses of centres in charge of flight information regions (FIRs) and/or upper flight information regions
(UIRs).
LOCATION INDICATORS
Location indicators are assigned by States and are checked by ICAO for conformity with the “Formulation and assignment of
location indicators” set out below.
Stability in location indicators assigned is important, hence changes should be made only after due consideration. This
document is published quarterly as a service to international aviation. Any errors or omissions should be brought to the
attention of the Secretary General of ICAO, 999 University Street, Montreal, Quebec, Canada H3C 5H7.
The development of a system of location indicators arose from Recommendations 1.2/3, 1.2/4 and 1.2/5 of the
Communications Division, Sixth Session (cf. Doc 7831), modified by Recommendation 3 of the Third Meeting and by
Recommendation 3/1 of the Sixth Meeting of the ICAO Panel of Teletypewriter Specialists. These recommendations were
approved by the Council at the 10th Meeting of its Thirty-second Session on 6 December 1957, at the 18th Meeting of its Thirtyfifth
Session on 15 December 1958, and the 12th Meeting of its Fifty-seventh Session on 4 April 1966 respectively. The
principles for the formulation and assignment of location indicators contained in these recommendations are given below.
DEFINITIONS
(Annex 10, Volume II)
Aeronautical fixed service (AFS) — A telecommunication service between specified fixed points provided primarily for
the safety of air navigation and for the regular, efficient and economical operation of air services.
Aeronautical fixed station — A station in the aeronautical fixed service.
Aeronautical fixed telecommunication network (AFTN) — A worldwide system of aeronautical fixed circuits provided, as
part of the aeronautical fixed service, for the exchange of messages and/or digital data between aeronautical fixed stations
having the same or compatible communications characteristics.
ATS message handling system (AMHS) — The set of computing and communication resources implemented by ATS
organizations to provide the ATS message handling service.
Location indicator — A four-letter code group formulated in accordance with rules prescribed by ICAO and assigned to
the location of an aeronautical fixed station.
FORMULATION AND ASSIGNMENT OF LOCATION INDICATORS
Four-letter location indicators shall be formulated and assigned to identify those geographical locations at which there is
situated a station forming part of the AFS.
Note.— Separate location indicators should not be assigned to different units at one geographical location when the
appropriate use of three-letter designators will adequately cover the need.