ICAO and the World Meteorological Organization


From the early days of aviation, it was realized that meteorological information was vital for the planning and a constant factor for the safe conduct of flights; pilots need to be informed about meteorological conditions along the routes to be flown and at their destination aerodromes. The high operating cost of modern aircraft means that optimum use must be made of available meteorological information and that forecasting accuracy must continue to be improved. The increasing use of flight management computers and the establishment on-board aircraft of reliable data links between aircraft and ground make it possible to monitor flight progress and update flight plans on the basis of new weather conditions. 

Brunei – 30 April 1986

Admission to International Organizations

Logos of WMO, ITU, UPU, ICAO


Beginning in 1853, many of the world's leading maritime countries tried to establish an international system for collecting meteorological observations made by ships at sea; the first International Meteorological Conference opened its proceedings at Brussels, Belgium, on the 23 August 1853 at the instigation of lieutenant Matthew Fontaine Maury of the US Navy. The first International Meteorological Congress was held in Vienna in September 1873 and led to the founding of the International Meteorological Organization (IMO, in French: Organisation Météorologique Internationale), composed of directors of meteorological services from various countries and territories throughout the world. This organization carried out ambitious programs to perfect and standardize international meteorological observations and to exchange such information internationally. Cooperation between ICAN and other IMO technical commissions related to aeronautical meteorology was ensured to reduce duplication as much as possible, although with some difficulties.


The Convention on International Civil Aviation, which came into force on 4 April 1947, had made provision for Annex I on Meteorological protection of international aeronautics. As standards were developed by ICAO, either the subjects of annexes were split or new annexes were conceived, and most of the titles were revised. Thus, a new Annex 3 titled Meteorological Codes was created and later renamed Meteorological Service for International Air Navigation. The purpose of this Annex is to make provision of meteorological information to operators, flight crew members, air traffic services units, search and rescue units, airport management and other concerned with aviation.


WMO Logo

In the meantime, the IMO worked mainly towards its transformation into a new Organization, with representatives of the respective countries, not their weather services. A conference of directors of national meteorological services met at Washington, D.C., from 22 September to 11 October 1947 under the auspices of the International Meteorological Organization and adopted the World Meteorological Convention, establishing the World Meteorological Organization (WMO, in French: Organisation Météorologique Mondiale) as the successor of the IMO. On 23 March 1950, after 30 signers had ratified or acceded to the convention, it came into force.


Working arrangements between ICAO and WMO were agreed and approved by both organizations during 1953 (approved by the Council of ICAO on 21 May 1953 and by the Executive Committee of WMO on 23 October 1953) for entry into force on 1 January 1954; an amendment to those arrangements was approved by the ICAO Council on 26 November 1962 and by the WMO Executive Committee on 16 October 1962) to become effective on 1 January 1963. The arrangements were designed to secure close cooperation and to establish machinery regarding the allocation to one organization or the other of primary responsibility for certain sectors within the field of common interest. In accordance with that document, ICAO is responsible for specifying the needs of the users/customers of aeronautical meteorological services, whereas WMO is responsible for providing the aviation community with operational meteorological information. WMO and ICAO maintain close and constant cooperation in keeping under review the requirements of meteorological services for aviation and in the adoption of procedures for the provision of these services, as well as keeping them up to date.


WMO Aeronautical Meteorology Programme is to further the application of meteorology to aviation by providing the aviation community with operational meteorological information. The main long-term objective of this programme is to ensure the worldwide provision of cost-effective and responsive meteorological services; in order to achieve this objective, WMO maintains close cooperation with its Member National Meteorological Services, and partner organizations, particularly ICAO and IATA.


IMO and later WMO established a Commission for Aeronautical Meteorology (abbreviated by CAMé and later CAeM), the main purposes of which are to assist Members in improving delivery of aeronautical meteorological observations and forecast services, and in applying quality standards in line with the requirements of aviation users; to coordinate development and implementation of aeronautical meteorological services in support of safe and efficient Air Traffic Management, in collaboration with the International Civil Aviation Organization (ICAO); to provide the best available guidance, resource material and coordination for aeronautical meteorological education and training to Members in cooperation with the regional associations, ICAO regional groups and the Education and Training Office of the WMO Secretariat.


Service cover sent by the International Meteorological Organization (IMO), Lausanne, Switzerland to Albert Roper, Secretary General of the Provisional International Civil Aviation Organization (PICAO) – Postmarked on 14 April 1947.

It is interesting to note that ICAO came into being on 4 April 1947, just a few days before this cover was sent to Montréal.




Service cover (front and back pictures) sent by ICAO Regional Office in Paris to WMO Secretary General in Geneva. Postmarked on 25 November 1955.

Red meter showing ICAO’s early emblem in use at that time.


Service cover sent from WMO to ICAO Secretary General.

Metered stamp dated 5 March 1959.



Argentina – Second Thematic Philatelic Exhibition (TEMEX ’60, sponsored by AFITA, Asociación Filatélica Temática Argentina) held in Buenos Aires from 4 from 9 December 1960. During this exhibition, a total of 12 covers were released paying tribute to the United Nations, its Programmes and Specialized Agencies; all covers are similar, except for the emblem, the colors of the UN Buildings in New York and the date of release. These covers were issued on different dates ranging from 4 to 9 December 1960; the above cover (see front and back) related to WMO was dated 8 December 1960. On the back of the cover, note the numbering and the number of 500 copies printed.


Registered service cover sent by WMO to ICAO Technical Assistance Bureau.

Postmarked on 23 Mars 1979.


Service cover sent by WMO to ICAO Secretary General.

Metered stamp dated 27 July 1982.


Service cover sent by WMO in 2009 to ICAO Secretary General

In 2009, the World Meteorological Organization (WMO) addressed a range of issues in order to enhance the provision of critical weather, climate and water assessments and services, as shown by the motto on the above envelope.