During the Chicago Conference technical annexes to the convention were drawn up. Some have the character of a standard and are the minimum mandatory for all signatory states of the Chicago Convention. Others are articulated as acceptable recommendations to a greater or lesser extent by the countries. The ICAO annexes cover practically all aspects of air transport and deal with technical issues that are fundamental for its standardization and regulation.

The Convention on International Civil Aviation (1944), also known as the Chicago Convention, was intended to update the rules on aviation. It is the most important regulatory treaty in relation to Public International Aeronautical Law.

In 1944, with the end of World War II approaching, the United States promoted a conference in order to update international agreements on civil aviation, practically stalled since the Paris Convention of 1919. The conference was held in Chicago on November 1 until December 7, 1944, with the attendance of delegates from 52 states. At that time, civil aviation was waiting for the end of the war to be relaunched, great technological advances had been made in aeronautics, the US economic potential was booming, while the great European powers, the USSR and Japan were totally in debt, with a civil aviation industry practically destroyed. This brought a confrontation between the United States, with an economically very strong position that sought a free international air market policy, against the rest of the countries, which wanted to adopt a protectionist policy to rebuild their aeronautical industries and their economies.