The Council of ICAO in 1950
On the technical side, the situation in post-war Europe was marked by the fact that no coherent navigation aids structure was available, that the ground-ground and air-ground communication systems were only partially in a state to correspond to the needs of operation under all conditions and that the air traffic services showed a wide variety in the procedures applied and in their efficiency. In addition, aeronautical information promulgated by States on available facilities and their operating status was insufficient or not available at all. The same also applied to the North Atlantic who constituted the vital link between Europe and the North American sub-continent.
Urgent action appeared therefore required and it was for this reason that PICAO convened the first regional meeting dealing with the North Atlantic in March 1946 (the North Atlantic Route Service Conference in Dublin) and the second in April 1946 (the European-Mediterranean Route Service Conference in Paris). In both meetings efforts were made to establish a route pattern to be used by international civil aviation and to determine the ground services and facilities which were required to allow a safe expeditious flow of air traffic.
The Boeing Strtocruiser entered airline service in 1949
To assist in the application of the agreed measures and to help in necessary co-ordination work between States, a temporary regional body to serve the European region was established in 1946 in the location of the CINA Offices with Mr. L.L. Bedin as Regional Representative. Also in 1946, a similar body serving the North Atlantic was set up in Dublin with Mr. E.M. Lewis as Regional Representative. This latter body was later moved to ICAO Headquarters in Montreal and the responsibilities for the North Atlantic Region were shared between this Office and the Paris Office so that the Montreal Office was responsible for relations with NAT States on the American Continent and Paris for relations with those in Europe and East of it. This situation lasted until the early 60's when the NAT Regional Office in Montreal was dissolved and Paris became responsible for looking after the NAT Region as a whole.
Since it was ICAO's declared aim to develop a world-wide air navigation system, it was obviously not possible for the two regional meetings mentioned above, to come to definite conclusions as to the aids to be used or the methods to be applied as long as this world-wide system had not yet been defined. To further this important work, three world-wide communication meetings were held from October 1945 to December 1946 (1. COM Meeting in October 1945, 2. Special Radio Technical Division (COT) in November 1946 and 3. COM Meeting in November/ December 1946). These were followed by a special Aeronautical Fixed Telecommunications Services (AFTN) Meeting in Brussels in January 1947.
To make a long story short, after exhaustive and profound discussions it was agreed that:
- the standard aid for approach and landing should be the Instrument Landing System (ILS);
- the standard short-range navigation aids should be the VHF omni-directional radio range (VOR) where necessary supplemented by a Distance measuring equipment (DME);
- aids to long-range navigation could be:
a. CONSOL;
b. Standard LORAN; grid
c. Low frequency (LF) LORAN
but that none of this yet qualified for designation as the standard long-range navigation aid;
- VHF voice-communication should be the primary means to conduct air-ground communication and HF voice-communication should be used where the use of VHF was not possible due to its inherent (line-of-sight)
- land-line teletype should be the primary means to realise the aeronautical fixed services telecommunications network (AFTN), supplemented by radio-teletype where land-line links were not feasible; and
land-line direct telephone lines should be the primary means to provide for direct controller-to-controller voice communications in the air traffic control services. With regard to the designation of the VOR as standard aid, it is to be noted that, until 1954, this decision led to very engaged discussions. As of 1946,the United Kingdom, while world-widely subscribing to a point-source navigation aid providing bearing and distance, maintained that there was a special requirement for a short-range navigation aid in Europe providing area coverage. In their view this was essential because of the particularly dense criss-cross pattern of potential air routes in Europe which resulted from the many population centres distributed nearly evenly throughout Europe and which, when served by point-source aids, would impose inordinate high economic demands on States, quite apart from possible technical (frequency assignment, siting) difficulties. The UK therefore originally proposed the GEE system and later the DECCA system as a supplementary navigation aid for Europe. For a number of reasons, not the least being that, at that time, an area system could only be realised with reference to a hyperbolic grid system, this proposal was not adopted.
Comet, first commercial jet aircraft used starting by 1952
Apart from preparing, organising and serving the 1st, 2nd and 3rd EUR Regional Meetings in 1946, 1948 and 1952 and the special meetings on ATC (1946) and on the AFTN (1947), the major task of the European Office until 1952 was to prepare and keep current the European-Mediterranean Manual (Doe 4700) a sort of European Aeronautical Information Publication (AIP) which was issued to provide States and international operators with information on aeronautical services and facilities available, or planned to be made available, to international air navigation. (With the advent of national AIP'S, this document was later given up as it turned out to be too difficult to keep it current).
In addition, the Office maintained liaison with those States to which it was accredited in order to assist in the co-ordinated implementation of agreed measures between States. Its personnel also performed numerous missions to States in order to obtain first-hand information on the existing situation and/or to provide information and advice as and when required.
By about 1952, civil air traffic that had been steadily growing since 1946 had reached proportions that, especially in the fields of air traffic control and air-ground communications, rendered the situation critical. In air traffic control, once more two concepts confronted each other namely:
- the concept that a safe, orderly and expeditious flow of air traffic could only be maintained by air traffic control if flights were routed along prescribed airways (corridors of a specified width, normally 10 NM, and covering all altitudes normally used by civil air transport operations) between their point of departure and their destination. When following these airways, flights would be controlled throughout their progression and be provided with clearances ensuring a collision-free flight path. This concept was based on experience gained in North America where air traffic densities had reached dimensions which, at certain locations, were vastly superior to those observed in Europe at that time; and
- the concept that air traffic control should be restricted to specified portions of the airspace around major airports only, while otherwise leaving it to pilots to plan and fly their own route except that information on the progress of other flights would be provided if the danger of a collision was likely. This concept was based on the assumption that channelling of air traffic into comparatively narrow corridors was: in fact, increasing the danger of collision while this was reduced when pilots chose their own route, thus obtaining a much more random distribution of traffic.
After prolonged and very engaged discussions (and a number of Close "encounters" between flights in "free flight areas"), the airway concept was finally adopted and a basic European airways network was developed.
In the field of air-ground communications, originally only 4 VHF channels were available (118.1 MHz for towers, 119.7 MHz for approach purposes, 122.1 MHz for area control and 121.5 MHz for emergencies) and these had in addition to be shared with the military. By 1952, the situation had therefore become somewhat "crowded" and it was found necessary to take corrective measures. It was for this reason that, in November 1952, a special frequency assignment meeting was held in the Paris Office which prepared a new plan for the assignment of frequencies to ATC facilities serving international air navigation operations based on the repetitive use of 19 VHF channels throughout the EUR Region.
In March 1952, France, as the host States of the European Office invited ICAO to convene the 3rd European-Mediterranean Regional Air Navigation Meeting in Paris and this turned out to be one of the biggest meetings that had so far been organised by ICAO. Some 350 representatives of more than 60 States were present and in 4 weeks of often hectic work it was possible to develop a Regional Plan covering all aspects of air navigation from aerodromes to search and rescue which were required to cater for international flight operations in the next 5-8 years. Refinements to this plan, especially as regards the ATS route Network and ATC air-ground communications were developed in two subsequent meetings in the Paris Office in the same year so that, by the end of 1952, a complete internationally agreed project for the development of international air navigation in a major area of the world was available.
Activities of the European Office up to 1954 - NAT Region
The major problem in the North Atlantic Region which was of concern to the Paris Regional Office at that time was that related to communications. Both, ground-ground and air-ground communications were mainly conducted via high frequency (HF) channels with all the technical and procedural problems that are inherent to this means of communication. Selection, attribution, assignment and specification of the particular operating mode and time for each available HF channel constituted the main task because all this required careful co-ordination between the operating stations on the ground that operated in a network configuration and with airline operators.
