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One Non-National European Sky

European Union
Complete with results
Geo-spatial type
Network corridors
Project Acronym
STRIA Roadmaps
Network and traffic management systems (NTM)
Transport mode
Airborne icon
Transport sectors
Passenger transport,
Freight transport


Background & Policy context

ONESKY is a preparatory, accompanying and support measure of the European Commission (DG TREN) in the 5th Framework Programme GROWTH, Sub-programme Area: Traffic management systems. Up till 2000, there has been a sharp and steady rise in delays to aircraft. This had major repercussions for users and placed a substantial financial burden on airlines. The delays were caused in particular by the air traffic control system, which appeared to be less and less capable of handling the phenomenal growth in air travel.


In 2001, one flight in four was delayed due to air traffic problems. Despite a temporary slowdown following the attacks on 11 September, estimates are that air traffic will grow by 4% a year over the next 15 years. Delays cost airlines between EUR 1.3 and EUR 1.9 billion a year. While there has been a constant increase in air traffic control capacity in Europe since 1990, it is now trailing three years behind the growth in air traffic. The technical improvements made by Eurocontrol, the international organisation for the safety of air navigation, have not been enough to reverse the trend and delays continue, in particular, in the more central areas of the European Union of 15 Member States.


Airspace is in fact still basically organised as it was in the 1960s. Each country regulates its airspace without regard to cross-border traffic flows: a flight from Rome to Brussels passes through nine different control centres. The Single European Sky is an ambitious initiative to reform the outdated architecture of European air traffic control. It comes at a time when improved air traffic and aircraft positioning and communication technologies, such as Galileo, offer opportunities for significant improvements in the efficiency and safety of air travel. It responds to the need to conceive developments in air traffic management as a building block of the Community transport policy, enshrined in the White Paper of 27 November 2001.


The objective of the ONESKY project was to develop proposals for a European airspace structure that are able to support an efficient traffic flow based on needs rather than on existing national structures. The proposals were developed regardless of national frontiers and acknowledging the new geopolitical realities when dividing the airspace between military and civil users.


ONESKY's proposals should be regarded as examples of what can be gained if sectors can be designed regardless of national boundaries. Two proposals/designs were produced together with two supporting studies:


1- A bottom-up, 'current airspace design'

2- A top-down, 'clean sheet design'


A- In support of these proposals the military issues related to airspace design were studied

B- Finally a cost-benefit analysis (CBA) of both design proposals was performed.


ONESKY will demonstrate that their proposals will, if implemented, result in an increase in airspace capacity.


The ONESKY work programme will be conducted using Fast Time simulation techniques within an accepted Validation Methodology.


The ONESKY project will follow two lines of action:


  • Line 1 will examine, within the current ECAC (European Civil Aviation Conference) airspace, those areas which contribute to the overall delays due to their having an artificial sector boundary imposed through adherence of a national frontier or through the inclusion of military airspace. The improvements to the overall efficiency of the ECAC area will be identified.
  • Line 2 will examine the efficiencies that may be gained across the ECAC area if the airspace could be designed 'from scratch'. While this is most likely an impractical proposition, it will identify the theoretical efficiencies that may be achieved and will produce a design that should act as an eventual aim.

One cannot perform an airspace design, without including the military aspects. Therefore a separate workpackage dealt with studying and implementing relevant military aspects into the above mentioned designs. Next to the military aspects, the two designs were also subjected to a cost-benefit-analysis.


Parent Programmes
Institution Type
Public institution
Institution Name
European Commission, Directorate-General for Energy and Transport (DG TREN)
Type of funding
Public (EU)


A closer look to these results and the 2001 Yearly ATFM Summary gives indications about the geographical positions of the actual 2001 problem areas. These indications are confirmed by the results of the reference scenario.

  • No sector of the Barcelona/Aix problem area appears in the 25 most penalising en-route sectors and no regulation is generated in this area in the reference scenario. The modifications made by Barcelona ACC and Aix ACC between 1999 and 2001 seem to have solved most of the ATC problem in this area. The redesign of these sectors should have little influence on the total delay (unless traffic patterns through these sectors change a lot).
  • In the Northern France/South-east England/Maastricht region, sectors EGTTS14 and LFEUE still seem to be very penalising in 2001, and the WP4 redesign may solve problems in this area. The redesign in this area produces about 50% (+/- 15%) of the computed gain. Furthermore, the Yearly ATFM Summary shows that 3 of the 4 most penalising sectors belong to Maastricht : EBMAWSL, EBMALUX, EBMALNL. It might seem useful to include these sectors in further redesigns of airspace. However, a further study should also consider recent Maastricht changes (not yet done in June-July 2001), which may have solved most of the ATC problems in this area.
  • No Italian sector appears in the most penalising en-route sectors, although some appear in our simulations, but with very small delays. It seems that, with the end of the Balkans conflict and the redesign of penalising sectors, a lot of ATC problems have been solved. For the same reason as for Barcelona/Aix, further sector redesign should bring little delay reduction.
  • Despite the restructuration of the airspace since 1999, there still are a lot of problems in the Switzerland/Southern Germany area in 2001. The redesign in this area produces about 50% (+/- 15%) of the computed gain. LSAZUP1-2, LSAGMS3, LSAGISE are within the 13 most penalising sectors in 2001. Only LSAZUP2-3 have been redesigned through the WP4 process, and it causes minor impact on delays. It may be useful to include other Switzerland sectors in further studies. But, once more, as said in the WP4 report, the changes made during 2001 prevent us to conclude whether or not Switzerland is still a problem area.
  • Cost-Benefit-Analysis Current Design: in the following, the main results of the redesign case are presented. The results have been assessed by developing a 'worst case' and a 'b

    Policy implications

    This report gives examples of what can be achieved by taking a Single Sky view when redesigning airspace, but that the designs described are relatively immature and would therefore need further input from local operational experts and assessment by real-time simulation before they should be considered for operational implementation (or deployment). Within the timeframe and resources of the project we were not able to develop a proposal which fully satisfies all requirements. However, in view of the sub-optimal character of the traffic samples and scenarios used (airport handling traffic more than their maximum and other not fully realistic elements) and the overall positive results of the redesigns, the consortium concludes that given further local optimisations (both regarding civil and military aspects) a solution, whereby traffic density is at a level originally predicted for the year 2005 (a 35% increase in overall traffic compared to 1999), is feasible.


    Looking at a scenario in which we continue with the present principles a so-called 'capacity wall' will come about in the very near future (indicated by the highly overloaded initial designs within the clean sheet study), leading to increased delays and costs. Therefore, adapting the principles of the 'Single Sky' initiative should be started as soon as possible.


Lead Organisation
EU Contribution
Partner Organisations
EU Contribution


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