Shortly after the establishment of the International Civil Aviation Organization in December 1944, the Interim Council recognized the need to subdivide the world into air navigation regions in order to facilitate the planning and implementation of ground services and facilities essential for international air transport operations. The two principal concepts which led to this conclusion are:
- as the operational and technical problems inherent in different parts of the world varied considerably, it was logical that the planning and implementation of the required ground services should be carried out on an area or regional basis - the geographical limits of which should be such as to encompass air route stages having a certain degree of homogeneity, and therefore entailing a somewhat uniform set of requirements; and
- planning the requirements for air navigation facilities and services is done through consultation among a limited number of States, rather than in preference to planning on a world-wide basis. These consultations are carried out on an area basis and normally through regional air navigation meetings. The need to conduct the planning of the facilities and services required for the world-wide network of international air routes in a small number of areas of manageable proportions is evident.
Considerations of a non-operational or non-technical nature, which may play a role in determining the requirements for air navigation services and facilities, are the geographical and climatological conditions that prevail in certain areas of the world and the means by which these requirements can be met in those areas.
With the foregoing in mind, the Interim Council agreed in 1945 to establish ten air navigation regions, the boundaries of which roughly coincided with the continental and oceanic masses. In defining these boundaries, provision was made for overlapping of the regions at the edges such that as many as possible of the terminals associated with the air route network for the region were included within the region. The original ten air navigation regions consisted of the African-Indian Ocean, the Caribbean, the European-Mediterranean, the Middle East, the North Atlantic, the North Pacific, the South American, the South Atlantic, the South Pacific and the Southeast Asian Regions. By 1952, the number of regions was reduced to eight by combining the North and South Pacific Regions into the Pacific Region and the South American and the South Atlantic Regions, retaining the name of the former.