History: Activities of the European Office from 1971 to 1985

EUR Region

Despite the limited Regional Meeting in 1968 and 1969, it was found that developments in the EUR Region required a further full-scale Regional Meeting in 1971 in order to up-date the air navigation system and make necessary provisions for the next couple of years. As already found in 1958 at the Fourth and in 1966 at the Fifth Regional Meetings, the size and complexity of the Meeting was again such that it proved impossible to prepare a complete Regional Plan in the time allotted to the meeting. In addition, it was also found that future developments in the Region were charged with by so many imponderables that reliable forecast about them and consequent measures based thereon could not be developed.

The Meeting agreed therefore on a new method of regional planning that envisaged:

a. a continuous review of the Regional Plan in order to adjust it in the light of developments, and

b. the creation of a special body, composed of representatives from designated States of the Region, in order to conduct this review and prepare, as necessary, proposals for corrective action which could be presented for adoption to all States of the Region (providers and users) whenever this was required by circumstances. As this appeared to many to be a rather drastic departure from the regional planning machinery, so far applied by ICAO on a world-wide basis, it was, however, agreed that this new process should be conducted on a trial basis and that a definite decision on it should only be taken once sufficient experience had been gained to allow a final judgement.

The Group constituted in accordance with the above was called the European Air Navigation Planning Group (EANPG) and, after its constitution agreed on the following working method:

c. the full group would meet twice yearly in plenary session to review the situation and based on this, propose action required to keep the Regional Plan current and/or to initiate action required to make timely arrangements for likely future requirements; and

d. the group would create working groups of limited duration, which were given specific tasks and which were to report the results of their work directly to the EANPG. The result of this was that, at times, up to 6 different working groups of the EANPG were in operation and, since the Paris Off-ice was charged with the task to give all necessary support to the EANPG and its subordinate bodies, its workload was considerably increased. In fact, this went so far that, in some years, some 30 to 35 meetings on a wide variety of technical and operational subjects had to be organised and serviced in the Paris Office and this in addition to the routine office tasks. However, at the same time, this activity also resulted in much closer international co-operation, especially in the fields of air traffic services, communications, aeronautical information services, communications, aeronautical information services, meteorology etc. than had previously been the case and this continuous collaboration between States strengthened the recognition amongst States that the air navigation system in the Region was truly international in nature.

The increase in sophistication and complexity of the equipment used in air navigation in general and especially in the provision of air traffic control accentuated two problems which had already previously existed but which now assumed major proportions:

e. the state of development of the national air traffic services in the Region varied considerably. This applied not only to the availability of supporting means (primary and secondary radar, communications, data processing equipment etc.) but also to the administrative and social provisions applicable to ATS personnel; and

f. once a certain complexity of the system had been reached, its further improvement became more and more costly, while the additional benefits obtained from these improvements (i.e. increases in traffic handling) tended to become smaller and smaller. In fact, it was found that, in certain highly developed national facilities, an expected increase in the traffic handling capacity by 10 % would increase the operating costs by some 50 to 70 %. The problem under a) required that, in any planning, account had to be taken of the existing situation and of the realistic possibilities of States regarding improvements to their ATC system, and this not only from the financial point of view but also with regard to "lead-times" of the industry manufacturing the required equipment and the necessary "break-in" time by personnel using the equipment routinely before it could be used to full advantage. In addition, it had also to be ensured that differences in sophistication between ATC facilities in adjacent States did not result in the imposition of unduly complicated or cumbersome operating methods on the less sophisticated unit, thus adding to its workload and operating costs without any gain in efficiency.

With respect to b), it was inevitable that the review of this question raised, on the one hand, the question of the ultimate traffic handling capacity which an air traffic control system could be expected to attain and, on the other, the costs which were involved in such a process. In short, the question of a reasonable relationship between cost and effectiveness of the air navigation system, which had already previously been a planning factor, albeit not of major significance, now assumed proportions which influenced more and more the technical and operational planning.

The question of the ultimate capacity of the air navigation system was, however, not only seen under cost aspects but it was also realised that technical developments had reached a stage where it was no longer possible to work with the philosophy so far applied that, if demand increased, human ingenuity would always find ways and means to satisfy it. A major event provoking discussion on this subject was the so-called "oil crisis" in 1973, which had far-reaching consequences on air transport in general and thus on air navigation. To mention just one aspect: fuel costs which had hitherto constituted some 10-12% of the total operating costs of an airline operator now rose to some 30-35 % of them. The immediate effect of this was that operators placed even more emphasis on the economy of their flight operations, i.e. they became much more sensitive to delays and/or route or altitude penalties imposed on their flights because the resultant additional fuel costs for a flight had a much greater impact on its economic efficiency. 

However, since the oil crisis had also marked effects on the general economic situation of practically all States, this, in turn, meant that they began to review their budgets for possible new sources of cost recovery with the result that amongst others, the free use of the en-route part of the air navigation system received closer attention, not the least because of the growing costs involved in its it was therefore believed necessary to explore other avenues. It was noted that the difficulties in the handling of air traffic were not equally distributed throughout a day, or throughout the week or the year. They occurred only during specific periods of the year (summer holiday season, Christmas season, Easter, specific events) and mostly during the end of the week and therein again at specific hours of the day, In addition, this peaking of traffic only affected certain heavily travelled routes and areas where large amounts of traffic were generated and this, in turn, was largely dependant on passenger habits or in some cases what operators thought passenger habits were. However, the effects of such a partial clogging up of parts of the route network extended nevertheless far beyond the immediately affected area. Uncoordinated efforts made by individual ATC units to limit the acceptance of air traffic in their area to a degree commensurate with their handling capability proved not only ineffective but increased the overall difficulties in size as well as in the affected area modernisation and in the resultant operating expenses. In short, by the mid-seventies, user charges for en-route services in order to recuperate progressively more and more of the operating expenses spent by States were a common theme in the Region. This gave an additional impetus to the cost-effectiveness discussions mentioned above and established economic considerations definitely as a major subject in any further planning for the air navigation system.

On the technical side and for the reasons stated above, it was realised that the limitations to the traffic handling capacity of the system, which continued to persist, could not be resolved at short notice by a simple expansion of the system capacity. In fact, there was doubt that this could ever be done in the light of the new economic situation and

Therefore, it soon became apparent that, if any scheduling measures intended to spread air traffic in time were to be taken, this could only be done on the largest possible scale, preferably on a regional basis. In addition it had to be ensured that any limitations imposed on operators could only be taken while their aircraft were still on the ground and it had to be ensured that such limitations affected all operators in an equitable manner. After long and complicated discussions, two possible alleviating measures were developed which, while not eliminating the difficulties, at least provided a certain alleviation of the unsatisfactory situation:

g. the progressive implementation of a one-way routing system between those points in Europe where most of the traffic was generated. This reduced not only the number of intersecting flights but allowed a tighter packing of air traffic along particularly heavily travelled routes; and


h. the progressive creations of a data bank on all repetitive flight operations so that ATC units could anticipate likely traffic loads and make appropriate manning and other arrangements.

In addition, certain procedural arrangements regarding the filing of flight plans and the transfer of flights from one ATC unit to the next were made which helped to accelerate and facilitate the flow of flight data and thus the flow of air traffic. Needless to say that Eurocontrol made valuable contributions in this respect and that the EANPG was a major asset by assuring the earliest possible application of any agreed relief measure, as well as by encouraging the specialised groups, dealing with these matter's, to reach speedy results of their work. That all these activities required continuous assistance by the Paris Office goes also without saying whereby not the least task was to keep all States interested in the EUR Region currently informed of all developments in order to avoid any feelings amongst States, not directly participating in this work, that their legitimate interests were not properly taken into account.

At the same time, the EANPG made a complete review of the modalities which had so far been used to develop and maintain current the Regional Plan for the EUR Region in order to make it a more effective tool not only for international but also for national planning by States. To this extent, it was necessary to redefine a number of basic concepts of regional planning and the relationship between the demands on the air navigation system as formulated by the users and their realisation by States after a consensus on them had been reached. In addition, it was agreed to include, into the Regional Plan, certain methods used by States which, when applied on a wider scale, would ensure more uniformity in the operation of the air navigation system. As a result of this work, the Regional Plan now contain:

i. assumed operating parameters, i.e. selected performance characteristics of aircraft, which can be assumed by ground services in rendering services to them;

j. basic operational requirement i.e. agreed needs which the air navigation system has to meet if it is to function satisfactorily;

k. planning criteria, i.e. all aspects which need to be taken into account when planning an efficient, economic and practical air navigation system; and

l. methods of application, i.e. efficient and economic ways to operate the air navigation system and which, when applied on a wider scale, make for more uniformity in the way in which the air navigation system is operated. It was also agreed to include, in the Regional Plan, material on specific subjects which were not yet of general concern throughout the Region but which could serve as guidance to States in their planning, once they were confronted with the need for action on the subject in question.

The above, seemingly somewhat abstract activities of the EANPG showed their essential importance as the EAN PG got more involved in the planning of complex sub-systems of the air navigation systems which were required to cope with additional or new requirements. Apart from the new subject of "air traffic flow management", the increased requirement for up-to-date aeronautical information on the operating status of the system and its facilities, latest meteorological information and Other relevant data, increased the amount of data which needed to be exchanged as well as the speed with which it had to be made available. It was evident that, in the long run, it would economically not be possible to provide special dedicated communication networks for each of these types of information. It was for this reason that world-wide efforts within ICAO to provide for one integrated exchange system for all data gained particular importance in the EUR Region and work on the "Common ICAO data Interchange Network (CIDIN)" received priority treatment by the EAN PG, even though it was realised that its practical implementation throughout the Region would require a comparatively long period.

At the same time it became apparent that the creation of such complex systems raised a number of new problems, not the least of which was the need for more rigidity in sequence and format in which data was inserted into the systems and the increased use of codes and/or abbreviations by the system to save space and time. In short, the intellectual and physical task of preparing data so that it was acceptable to a given technical system for manipulation, and the correct interpretation of results produced by the system, required more and more specialised skills from the operator concerned, thus detracting him from his major duty, i.e. to serve air traffic. It was therefore believed necessary to strike a reasonable balance between automation (with its inherent rigidity) and the need for flexibility in the application of procedures by human operators to cater for non-routine situations. Finally, it was found that, the more expanded such systems were, the more difficult it became to Make changes to its operation in order to respond to new or changed requirements and this for mere technical reasons such as changes in the software and the associated inevitable debugging and/or modifications of specific data manipulation processes by the equipment.

As of the mid-seventies, it was also found that, due to the increase in general aviation activities (i.e. non-commercial flight operations in the lower airspace and around already busy airports and their mixture with low-level military flight operations, especially in the crowded Central European airspace) a new requirement for improved air traffic services to this type of flights arose. To make this possible, some States developed a new airspace structure with associated advisory services and/ or mandatory requirements for the carriage of specific types of navigation and/or communication equipment and the certified ability of pilots to use these. However, as these new problems 'were originally only felt by a limited number of States, each of them sought its own solution to it, with the end result that, by 1978, a wide variety of requirements and operating practices were in use which, while adequate for the local area in hich they were applied, rendered life fairly confusing for pilots engaged in international operations because of the need for frequent adjustment to new environments and procedures.

The EANPG therefore agreed on the need for work in this field in order to develop a common policy amongst all States concerned and also a common set of provisions. Very soon it became apparent however that a basic solution to this question could not be limited to the EUR Region alone but might require a revision of existing world-wide ICAO provisions regarding the visual flight rules and the classification of airspace. Based on the conditions existing in the EUR Region, the EANPG prepared a number of proposals and these are now under consideration by ICAO in a worldwide review.

By 1980, the work of the EANPG had progressed to a point where it was felt necessary to present it to a special Regional Meeting in order to find out whether States were in agreement with the manner in which the EANPG operated and also to obtain a mandate and, if necessary, new directives for its further activities. In addition, the specific subject of air traffic flow management, one of the main preoccupations in the Region, had been developed to the point where it was advisable to obtain a region-wide policy-decision as it was evident that any measures in this field would have at least region-wide implications. This applied particularly to the regional data bank on air traffic movements for whose creation Eurocontrol had become the focal point. Based on proposals presented to the Meeting, it agreed that the activities of the EANPG should continue and that work on air traffic flow management, including the establishment of a central air traffic data bank, should be pursued along the lines proposed.

After 5 more years, during which the EANPG continued its work while constantly refining its working methods in the light of experience gained, the Seventh Regional Air Navigation Meeting was held in 1985 in Malaga (Spain) and it produced the following results:

m. it defined permanently the basis on which air navigation planning in the Region should be conducted;

n. it agreed on the structure and presentation of the E U R Regional Plan;

o. it agreed on the manner in which the Regional Plan should be managed, including the retention of the EANPG as the permanent managing organ;

p. it defined the scope and structure of future EUR Regional Meetings;

q. it developed the measures required to improve the airspace organisation and the flow of air traffic in the Region; and

r. it described likely future developments and trends in air navigation in the medium and long term. Translated into practice this means that regional planning in the EUR Region is now done on a permanent basis with the possibility of inserting into the planning process latest developments on the international as well as the national level of individual States. To this extent, the Paris regional office will serve as the focal point at which all information will be collected and where arrangements will have to be made for its processing and the inclusion of relevant decisions and agreements into the EUR Regional Plan.

Quite apart from achieving very substantial practical results, it should also be noted that this Meeting was able to conclude its work in only 11 days, as compared to the previous 4 weeks of hectic activities. This also was mainly due to the fact that, because of the preparatory work done under the auspices of the EANPG, the Meeting had been presented with a comprehensive supporting documentation and clear and concise proposals.

Concorde, the first supersonic aircraft used
to cross the Atlantic, reduced the flight time by half
NAT Region

The introduction of "composite separation" in the North Atlantic track system had brought a certain relief to the traffic congestion in that Region because it increased the traffic handling capacity during peak periods. However, it soon became apparent that this could only be considered as a temporary relief measure. This even more so because the main difficulty still remained, i.e. the comparatively large economic penalties for all those flights which could not be accommodated on those tracks which were aligned in the narrow corridor surrounding the "minimum time track" (it is recalled that the normal lateral separation between adjacent tracks on the same level was still 120 nautical miles. To make things worse, the "oil crisis" of 1973 and its consequences on the operating costs significantly increased the economic penalties for those flight operations which were required to operate along the outer edges of the NAT track structure and more especially those which, because of their origin and destination (Southern Europe to Canada and vice versa), were required to cross the main East-West traffic flow. These flights could only fly under the track structure or above it, the latter not always being possible because of aircraft weight limitations, and this meant flight at uneconomic levels over long distances as long as the lateral extent of the route structure was a multiple of 120 nautical miles.


It was for this reason that, from 1971 on, the NAT SPG concentrated its efforts on the possibility of reducing the lateral separation between adjacent tracks in the track structure to 60 nautical miles, thus reducing its overall lateral extent by about half and bringing appreciable economic relief to both, crossing flights as well as those required to operate at the outer tracks of the structure itself. (An intermediate reduction to 90N M as agreed in 1965 was, for a number of practical reasons not found suitable). It was, however, realised that such a "quantum jump" in the reduction of lateral separation could not be achieved without appropriate safeguards in order to maintain the essential safety of flights. Of these, the most obvious was to ensure that the pilots' ability to follow their assigned route as closely as possible was ensured under all likely circumstances. The most promising development in this respect was the continuous increase in the number of aircraft equipped with inertial navigation systems and the availability of the long-range navigation system "OMEGA". Experience with these two systems had shown that, on average operations across the North Atlantic, aircraft could keep to their assigned track within very close tolerances and also that the reliability of these systems was sufficiently high to make failures a comparatively rare event.

Based on these conditions, the NAT SPG developed a concept which envisaged that States would ensure that aircraft on their register - would meet specified values of navigational accuracy (minimum navigation performance specifications - MNPS) and that only aircraft so certified could operate within a specified area in the North Atlantic where a lateral separation of 60NM between adjacent tracks would be applied. At the same time, the NAT SPG developed a proposal for the reduction of longitudinal separation between successive jet-aircraft on the same track and the same level, based on experience gained by oceanic control centres on both sides of the Atlantic. This so-called Mach Number technique envisaged that aircraft following each other would be assigned to this speed with the least possible variation. This then made it possible to assume that, while the assigned distance between any two aircraft (expressed in time of passing over the same reporting point) could slightly vary due to the fact that the two aircraft could, at any given time, be exposed to different meteorological conditions (especially winds), they nevertheless could never come in dangerously close proximity to each other.


In 1976 these proposals of the NAT SPG were presented to a limited Regional Meeting of North Atlantic States and were there adopted for application in the NAT Region. In 1977, the MNOS area was established in the NAT Region and, while still retaining 120NM normal lateral separation with the addition of a few tracks, based on composite separation, only MNPS certified aircraft were allowed to operate in the designated MNPS airspace. This was done in order to obtain data on radar-observed track deviations, which could serve as a basis for the assumption that the use of 6ONM lateral separation was feasible. Three years of observation and indoctrination of all concerned by States and operators through constant education and follow-up of recorded deviations with crews concerned resulted by 1980 in a situation where all parties concerned (States, operators and pilots) reached a consensus that the use of 60NM lateral separation in the designated MNPS airspace was a sage procedure.

At the same time, the consequent application of the Mach number technique had also shown that a reduction of the longitudinal separation from 30 to 15 minutes was also a sage proposition. It Was therefore agreed that these new separation minima, together with a rigid surveillance system and a specific follow-up procedure for each case of an observed abnormal deviation from track, should be implemented as of autumn 1980 and the results achieved to this day have shown that these measures were fully justified by practical experience.

With respect to these measures, it should be noted that they constituted the result of some 15 years of probably the most profound studies ever made in air navigation' matters and that they had been achieved thanks to an international effort by States and international organizations which despite differences in technical and procedural matters, had been conducted in a truly co-operative spirit and for the benefit of international air transport.

Since 1981 and up to 1985, the NAT SPG has continued its efforts to improve the air navigation situation in the North Atlantic while maintaining the extraordinary safety record in that Region. This work envisages, inter alia, improvements to the methods of flight planning by the provision of still better meteorological data, more flexibility in the conduct of flights and further reductions in the separation applied between individual flights, commensurate with improved methods of navigation and surveillance and without loss of safety.


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