The International Civil Aviation Organization is a specialized agency of the United Nations. It codifies the principles and techniques of international air navigation and fosters the planning and development of international air transport to ensure safe and orderly growth.
Its headquarters are located in Montreal, Quebec, Canada.
International Commission for Air Navigation (ICAN) was forerunner of ICAO, which continued to operate until 1945. In 1944, 52 countries signed the Chicago Convention on International Civil Aviation, also known as the Chicago Convention, in Chicago, under whose terms, a Provisional International Civil Aviation Organization (PICAO) was to be established. Thus in 1945, PICAO was established replacing ICAN.
In 1947, PICAO was disestablished and replaced by ICAO. In October 1947, ICAO became a specialized agency of the United Nations linked to the United Nations Economic and Social Council (ECOSOC).
As of November 2017, there are 192 ICAO members, consisting of 191 of the 193 UN members (all but Dominica and Liechtenstein), plus the Cook Islands.