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.”


The 8th and last Session of PICAO’s Interim Council was held from 29 April to 7 May 1947; the first Session of the ICAO Assembly was held in Montréal from 6 to 27 May 1947 and the ICAO Council held its first session from 28 May to 1 July 1947. The Council’s first official act, at its initial meeting on 28 May 1947, was the election of Dr. Edward Warner, as its President and the appointment of Dr. Albert Roper as Secretary General.


The goal of PICAO’s Interim Assembly (held in Montréal from 21 May to 7 June 1946) was to discuss, among other things, the steps to be taken so as to ensure that the transition from the provisional to the permanent organization proceed smoothly and without interruption in the work. Like the Interim Council, the structures of the Interim Assembly of PICAO, the secretariat and the various committees and commissions were fashioned along the same lines as those envisioned for the permanent organizations and set out in the Chicago Convention. Maintaining a kind of continuity between the provisional and the permanent organization was an end in itself.


Agenda item 1 submitted to Commission I of the Interim Assembly (General Policy of PICAO), related to authorizing the Interim Council to take the necessary steps for the establishment and implementation of the permanent Organization, was adopted without dissent.


After the Interim Assembly, preparations for the first meeting of the permanent organization were well underway. The Interim Council encouraged all States to ratify the Chicago Convention as soon as possible; it also agreed, in an effort to ensure a smooth transition, that the major positions in PICAO would continue to function until they were replaced by similar ones in the permanent organization. It continued assessing the reports of the Air Navigation and Air Transport Committees and the regional meetings. The Interim Council worked on the preparation of an agenda for the First ICAO Assembly and continued its ongoing efforts to attract personnel, preparing budgets, and establishing the requirements of the permanent Organization.


PICAO is to be credited with very useful work, in preparing the draft rules of procedures for ICAO’s Assembly and Council, setting up the working methods for the Council, organizing the Secretariat, and selecting both the President of the Council and the Secretary General who would become officials of ICAO.


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.


With the safety of international aviation being the primary objective of PICAO and ICAO, it is not surprising that much attention was focused on establishing the rules of the air with a view of facilitating the movement of air traffic while at the same time maximizing air safety. PICAO and ICAO largely benefited from its predecessor, the ICAN, in that the rules laid down by the latter Organization were already accepted and used by most nations.


The first twenty-six States that ratified the Chicago Convention.


Standard letter forwarded to all PICAO staff on 3 April 1947, regarding the appointment in the Secretariat for the transition from PICAO to ICAO.


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 (see PICAO sample at the left, incoming date: 22 March 1946), 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.


Council in Session in 1950.