Annex 7 – Aircraft Nationality and Registration Marks


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.


Annex 7

Annex 7 Aircraft Nationality and Registration Marks adopted by the International Civil Aviation Organization (ICAO) provides Standards & Recommended Practices for the display of appropriate aircraft nationality marks, common marks and registration marks which have been determined to comply with Articles 17 to 21 of the Chicago Convention.

The concept of nationality for aircraft was adapted from maritime law where the national flag is used to indicate a ship’s country of registration. The questions related to technical and legal aspects relevant for the future of aviation, among which was that of aircraft registration, were considered at the Paris Conference of 1910. While this Conference was unsuccessful in that it did not result in a signed agreement, the draft it produced subsequently formed the basis for the 1919 Paris Conference. The First Commission of the latter Conference, that dealt, among other things, with the registration of aircraft, came up in Annex A - Registration of Aircraft with a list of nationality marks for the participating countries; it is to be noted that the identification with one letter for five countries was based on the call sign prefixes adopted by the 1912 Radiotelegraph Conference, held in London. The intention being that other states adopting later the Convention Relating to the Regulation of Aerial Navigation should inform the International Commission for Air Navigation (ICAN) of the nationality mark chosen. The Commission would act as the coordinating body, ensuring that they did not duplicate those already allocated.

Final Protocol related to the International Radiotelegraph Convention signed in London in 1912.

At the second Session of ICAN held in London in October 1922, the French Delegation suggested that it would be more practical to adopt the same letters for aircraft nationality marks as those allocated for use as wireless call signs. For reference, at the London International Radiotelegraph Conference, held in London from 4 June to 5 July 1912, the International Telegraph Union (ITU, known as from 1 January 1934 as the International Telecommunication Union) had already made a list of letters to be used as call signs for wireless calls; the resulting International Radiotelegraph Convention came into force on 1 July 1913. Although initial allocations of the latter Convention were not specifically for aircraft but for any radio user, the Convention Relating to the Regulation of Aerial Navigation thus made allocations specifically for aircraft registrations based on the 1913 call sign list and its further revisions adopted at the ITU Conferences: the International Radiotelegraph Conference held in Washington, USA from 4 October to 25 November 1927, the International Radiotelegraph Conference held in Madrid, Spain from 3 September to 10 December 1932, the International Radio-communications Conference held in Cairo, Egypt from 1 February to 8 April to 1938).


List of country prefixes for the 27 States which signed the Convention Relating to the Regulation of Aerial Navigation on 13 October 1919.

According to the latest version of the Convention Relating to the Regulation of Aerial Navigation, the nationality and registration marks borne by the aircraft shall be constituted by a group of five letters:

·         The nationality shall be indicated by the first letter or the first two letters of such group, selected from the series of nationality symbols included in the radio call signs allocated to the state of registry by ITU.

·         A hyphen shall be placed immediately after the nationality letter or letters.

·         The registration shall be composed of three or four letters, forming with the nationality a maximum of five letters.

·         Examples: F-ABCD or HS-XYZ.

·         The nationality and registration marks shall be painted on the aircraft or affixed by any other means ensuring a similar degree of permanence.

·         The letters shall be capital letters in Roman characters without ornamentation.

·         Once the nationality mark is selected, the State notifies ICAO.

The aircraft marks identify distinctively a civil aircraft, in similar fashion to a license plate on an automobile. The markings have been amended and completed over the years. With the coming into existence of the permanent International Civil Aviation Organization (ICAO) in April 1947, the status of the standards prepared at the Chicago Conference underwent major changes. So, the original Annex H - Aircraft Registration and Identification Marks became Annex 7 - Aircraft Nationality and Registration Marks. The ICAO Council adopted the first standards concerning this issue on 7 February 1949; they became effective on 1 July 1949. The standards on markings have been amended by ICAO over the years.

Isle of Man (United Kingdom) – 1984 - 40th Anniversary of ICAO and 50th Anniversary of the first official airmail service to the Isle of Man. Maximum Card.

 Britten-Norman BN-2A-26 Islander of Haywards Aviation

(Registered G‑AXXJ in United Kingdom, c/n 150, 1970).

Annex 7 to the Chicago Convention prescribes the size, format and position the nationality and registration marks on the hull of the aircraft, and also the format of the Certificate of Registration that is to be carried in the aircraft at all times. The nationality mark (prefix) should precede the registration mark (suffix). Depending on the country, the registration mark is a numeric or alphanumeric code and consists of one to five digits or characters. In accordance with Para 2.3 of Annex 7, the nationality marks shall be selected from the series of nationality symbols included in the radio call signs allocated to the State of Registry by the International Telecommunication Union (ITU) (making the registration a quick way of determining the country of origin) and shall be notified to ICAO. The letters shall be capital letters in Roman characters without ornamentation; the numbers shall be Arabic numbers without ornamentation.

A hyphen or dash separates the nationality mark and the registration mark, except in the United States of America where the nationality mark is N immediately followed by a set of alphanumeric characters for the registration; the registration number is also referred to as an "N-number", as all aircraft registered in the USA have a number starting with N (example: N26789 used for Grumman American Avn. Corp, Serial number AA5A0723, Model AA-5A).

The Supplement to ICAO Annex 7 provides information with regards to differences between the national regulations and practices of Contracting States and the corresponding international standards contained in Annex 7; it also provides the list of aircraft nationality marks, national emblems and common marks.


At the time when the Chicago Convention was adopted, commercial aircraft were predominantly purchased directly by their operators who then retained ownership of such aircraft for use during most or all of their useful lives. Changes to aircraft nationality were not common since an aircraft tended to reside within one State for most or all of its useful life. However, over the past three decades, aircraft operators have realized substantial capital and operational efficiencies by leasing (rather than owning) a portion of their fleets for various periods of time. Based on various studies, the aircraft leasing market will continue to grow.


As a result, aircraft will most likely be transferred from one operator to another changing nationality multiple times during their useful lives. The change of aircraft nationality or registration from one State to another is referred to as cross-border transfers of aircraft. The increase in the number of cross-border transfers of aircraft globally, along with differences in States’ regulations, requirements and practices has highlighted certain inefficiencies in a global system that was developed when cross-border transferability was relatively uncommon.


In 2017, ICAO launched the cross-border transferability initiative with the aim of improving, standardizing and enhancing the efficiency of the cross-border transfers of aircraft and at the same time, ensuring that aviation keeps and improves its remarkable safety record. With the support of subject matter experts from Member States, international organization and industry, ICAO is currently undertaking a structured review of relevant ICAO Annexes, guidance material, various processes and practices established by States in order to identify issues diminishing the effectiveness and efficiency of cross-border transfers. Based on the outcomes of the review, mitigation strategies will be developed to address the identified issues.


Within the ICAO philatelic collection, one can find many stamps with aircraft reproductions bearing nationality and registration marks. A few examples are provided hereafter.



Sao Tome and Principe - 21/12/1979 - 35th Anniversary of ICAO; history of aviation, powered flight.

Spirit of St. Louis (1927) flown by Charles Lindbergh and registered in the experimental category N-X-211 in the USA (officially known as the Ryan NYP, for New York to Paris; s/n 7331); ICAO emblem.


Zambia - 26/01/1984 - 40th Anniversary of ICAO.   

de Havilland D.H.66 Hercules of Imperial Airways (circa 1931); registered G‑AAJH "City of Basra" in United Kingdom (c/n 393).


Hungary - 13/01/1994 - 50th Anniversary of ICAO.

Douglas DC‑2-120 from American Airlines (indicated DC‑3 on the stamp) registered NC14278 in USA (indicated on the upper-right wing, c/n 1311) over Jeppesen Low Altitude Enroute Chart (Budapest‑Bratislava region); 50th anniversary logo.


Monaco - 17/10/1994 - 50th Anniversary of ICAO.

Eurocopter AS-350B Écureuil (Squirrel) helicopter from Heli Air Monaco, registered 3A-MMC in Monaco; view of Monaco Heliport and 50th anniversary logo.


Cuba - 09/11/1994 - 50th Anniversary of ICAO.        

Douglas DC‑3 from Compañia CUBANA de Aviación S.A. and 50th anniversary logo. Registered CU-T172 in Cuba (c/n 11671).

Error: The article "la" is not needed in the Spanish name of the Organization (Organización de Aviación Civil Internacional).


Lesotho - 17/11/1994 - 50th Anniversary of ICAO.  

Depicts a mosotho horseman accompanying his wife to the airport; de Havilland Canada DHC-6-300 Twin Otter from Lesotho Airways; 50th anniversary logo. Registered 7P-LAP in Lesotho (c/n 837).   

Saint Vincent and The Grenadines - 01/12/1994 - 50th Anniversary of ICAO. 

Dornier Do 228-200 aircraft from the fleet operated by Air Martinique, at Bequia Airport, registered F-OGOZ in France (c/n 8161); 50th anniversary logo.