In response to the invitation of the United States Government, representatives of 54 nations met at Chicago from November 1 to December 7, 1944, to "make arrangements for the immediate establishment of provisional world air routes and services" and "to set up an interim council to collect, record and study data concerning international aviation and to make recommendations for its improvement." The Conference was also invited to "discuss the principles and methods to be followed in the adoption of a new aviation convention."
2. The International Air Services Transit Agreement, commonly known as the Two Freedoms agreement, was concluded and opened for signature. This agreement had been accepted by 36 states as of June 30, 1947. It has done much to strike the shackles previously limiting the development of world-wide air commerce.
3. The International Air Transport Agreement, commonly known as the Five Freedoms agreement, was also concluded and opened for signature. Although it was known at the time that this agreement would not be acceptable to a number of states, it served a temporary useful purpose for the states that did accept it. The number of accepting states reached a maximum of 17, but it is now declining, 4 having denounced the agreement. The United States gave notice of denunciation of its acceptance on July 25, 1946, and ceased to be a party to this agreement on July 25, 1947.
4. A standard form of bilateral agreement for the exchange of air routes was prepared and recommended by the Conference as part of its final act. This standard form has subsequently been widely used and has done much to bring a measure of consistency into the many new bilateral agreements which have been necessary.
5. An Interim Agreement on International Civil Aviation was completed and opened for signature. It came into effect on June 6, 1945, thereby providing an interim basis for many phases of international civil aviation and a constitution for the Provisional International Civil Aviation Organization. The interim agreement was replaced when the convention came into effect on April 4, 1947.
6. Finally, a world-wide common basis was established for the technical and operational aspects of international civil aviation. The technical contributions of the Conference, as printed in the present volume under the title "Drafts of Technical Annexes", run to some 188 pages of recommendations on such matters as airworthiness of aircraft, air traffic control, and the like. This comprehensive body of technical material undoubtedly represents the most striking advance ever achieved at a single conference in the field of international technical collaboration. The technical recommendations prepared at Chicago and the later revisions prepared by the Provisional International Civil Aviation Organization have served as a guide to practice throughout the world and have been of basic importance in the extraordinary expansion of international civil aviation which has occurred since 1945.