The Chicago Convention, 1944
In November 1944, with the Second World War still raging, 52 states convened in Chicago to negotiate how international civil aviation would work after the war. Thirty-seven days later they produced the Convention on International Civil Aviation — the foundational treaty that still governs global airspace sovereignty, ICAO, and the entire framework of international flight.
The Context
The US convened the conference in September 1944. The war in Europe was approaching endgame; the US and UK dominated Allied aviation industry. Commercial aviation had grown explosively in the interwar period, largely uncoordinated. The 1919 Paris Convention had attempted a framework but with limited scope. Post-war civil aviation needed a new instrument.
52 states attended; the Soviet Union withdrew at the last minute. Key disagreements turned on the scope of commercial rights — the US pushed for liberal open-market aviation; the UK and others wanted state-controlled bilateral rights.
What Was Agreed
The central achievement was Article 1 — the declaration of complete and exclusive state sovereignty over national airspace. This became the constitutional principle of global aviation. See detailed Chicago Convention explainer.
The Convention created ICAO, standardised operational technical requirements (later organised into the 19 Annexes), and framed the "freedoms of the air." Commercial-rights questions were punted to parallel instruments — IASTA (first and second freedoms) and bilateral air service agreements — rather than decided in the Convention itself.
Entry Into Force and Expansion
The Convention required 26 ratifications to enter into force; this was achieved on 4 April 1947. ICAO was inaugurated the same month. Over the following decades, membership grew to 193 states — effectively universal among UN members.
Historical reference. See Terms of Service.