The advent of jet aircraft in 1957-1958 led to the introduction of considerably longer route stage lengths, many of which traverse the full extent of two or more regions. Moreover, as the number of jet aircraft increased, the operational and technical problems encountered throughout the world progressively lost much of their regional character. This, in turn, pointed to the need for a further revision of the regional structure, and the 14th Session of the ICAO Assembly directed the Council to undertake a study of the regional structure in the light of existing and future developments, and to overcome certain problems such as those posed by the overlapping of the regions and by the non-inclusion of certain areas.
The results of the Council's study confirmed that planning on an area basis should continue and that the concept of dividing the world into air navigation regions should be retained, but mainly to provide a starting point in establishing the geographical area to be considered by a particular regional air navigation (RAN) meeting, and to serve as a basis for the distribution over a series of air navigation plan publications of all planned facilities and services resulting from the regional planning processes. Thus, with these objectives in mind, the Council redefined the air navigation regions in 1964 on the understanding that the area to be considered by a regional air navigation meeting could embrace one or more air navigation regions, or parts thereof, depending upon the coverage of the international air route network established by the Air Navigation Commission for consideration by that meeting. At the same time, the Council eliminated any overlapping between regions, included the associated polar areas in the regions, changed the name of the European-Mediterranean Region to the European Region, and established a North American Region to encompass Canada, the United States and the associated polar area. In 1980, the Council also renamed the South East Asian Region as the Asia Region.
The present regional structure, as defined in Appendix 1 to the Directives to Regional Air Navigation Meetings and Rules of Procedure for their Conduct (Doc 8144-AN/874), comprises the following regions:
- AFRICA-INDIAN OCEAN (AFI) REGION;
- ASIA (ASIA) REGION;
- CARIBBEAN (CAR) REGION;
- EUROPEAN (EUR) REGION;
- MIDDLE EAST (MID) REGION;
- NORTH AMERICAN (NAM) REGION;
- NORTH ATLANTIC (NAT) REGION;
- PACIFIC (PAC) REGION; and
- SOUTH AMERICAN (SAM) REGION.