From PICAO TO ICAO: Organizational similarities


The government of the United States conducted explanatory discussions with other allied nations from mid-1943. On the basis of the talks, invitations were sent to fifty-five allied and neutral states to meet in Chicago, USA, from 1 November 1944. For seven weeks, the delegates of fifty-two nations considered the problems of international civil aviation. The most important result of the conference was the drawing up of a Convention on International Civil Aviation (i.e. the Chicago Convention), the charter of a new body established to guide and develop international civil aviation.


It was provided that, thirty days after the governments of 26 nations (i.e. half of those present at the Conference) ratified the Convention, the new organization to be known as the International Civil Aviation Organization (ICAO) would come into existence.


Anticipating that a considerable time was certain to elapse before 26 governments ratified the Convention, the Conference provided for a provisional body to function in the interim period, as per Interim Agreement on International Civil Aviation (Article 1 - Section 1). This was the Provisional ICAO (PICAO), which began to function in August 1945. PICAO was to remain in existence until the permanent organization was created, but its life in any case was restricted to three years (Article 1 - Section 3 of the Interim Agreement).


On 5 March 1947, Spain was the 26th state to deposit, with the Government of the USA, its instrument of ratification to the Chicago Convention. Consequently, the Convention came into force on 4 April 1947 (i.e. 30 days later), among the states having thus ratified. Recognizing the necessity of continuity during the transition from the provisional to the permanent Organization, the first Interim Assembly of PICAO, held from 21 May to 7 June 1946, had directed that, on the coming into force of the Convention, the Interim Council, its officers, the Secretariat, and the other organs of PICAO would continue to function under the existing rules and regulations until they were replaced by corresponding organs of the permanent ICAO. Moreover, Article VII of the Interim Agreement on International Civil Aviation provided that “At the time of the coming into force of the Convention on International Civil Aviation signed at Chicago on 7 December 1944, the records and property of the Provisional Organization shall be transferred to the International Civil Aviation Organization established under the above-mentioned Convention.”


As forerunner of ICAO, the International Commission for Air Navigation (ICAN), which was established by the Paris Convention of 13 October 1919, was the first attempt to bring about the orderly development of international civil aviation. ICAN was dissolved when the Chicago Convention came into force and its assets were transferred to ICAO. Moreover, when it came into force on 4 April 1947, the Chicago Convention superseded the Havana Convention, signed on 28 February 1928.


1947 - Melbourne Regional air navigation (RAN) meeting.

Postcard with conference hand-stamp: P.I.C.A.O. – Melbourne, Aust.

Autographed by H.A. Robertson, Postmaster.


1953 - Melbourne Regional air navigation (RAN) meeting.

The conference hand-stamp: I.C.A.O. – Melbourne, Aust. was reutilized from the first meeting, with the letter “P” in front of the text cut out.


1947 - Melbourne Regional air navigation (RAN) meeting.

Registration label with the abbreviated name of the Organization (P.I.C.A.O.), along with the abbreviated place (Melb.) and country (Aust.) of the meeting.


1953 - Melbourne Regional air navigation (RAN) meeting.

As it can be noticed, the hand-stamp used for the first meeting was reutilized for the second meeting; however, the letter “P” had been cut out and the positioning of “I.C.A.O.” on the stamp remained the same.


At that time, a red receiving stamp or mark was applied to the incoming mail. The positioning of “ICAO" on the rubber stamp was off to the right and clearly indicates that the stamp had been in use at the time of PICAO, the letter "P," which preceded the other letters, having been cut out of the stamp when ICAO came into being on 7 April 1947.

More background information on this card can be found

by clicking on: The Story Behind the ICAO Card.


Commercial cover sent to Albert Roper as Secretary General of PICAO, with a postmark dated 12 May 1947 (a few weeks after ICAO came into being); news regarding the establishment of the permanent ICAO had not flown fast enough to reach the ministries of all governments.