The Convention on International Civil Aviation (also known as Chicago
Convention) was signed on 7 December 1944 by 52 States. Pending
ratification of the Convention by 26 States, the Provisional International
Civil Aviation Organization (PICAO) was established. It functioned
from 6 June 1945 until 4 April 1947. By 5 March 1947 the 26th
ratification was received. ICAO came into being on 4 April 1947. In
October of the same year, ICAO became a specialized agency of the
United Nations linked to Economic and Social Council (ECOSOC). The
Convention on International Civil Aviation set forth the purpose of
ICAO in the preamble: