Today's system failure at National Air Traffic Services' (Nats) West Drayton control centre is the latest in a series of set-backs to its £1bn modernisation project.

As the company fights to become more competitive in a changing European landscape, it is investing up to £500m in upgrading its core IT systems.

The question that is now raised is whether more of these system failures will occur in the coming months and years as the upgrades continue.

Nats is working hard to become more competitive as Europe moves to consolidate its air traffic control as part of its Single European Sky (SES) policy, making the upgrades a necessity.

In January, the EU Parliament voted in favour of the Single European Sky initiative, backing the creation of a single air traffic control system across Europe.

Experts say the legislation will almost certainly result in a consolidation in the number of ground control centres across Europe, a process that will be negotiated and decided on by individual governments.

In recognition of these changes, Nats last month announced a new senior manager to boost its plans to be influential in Europe, and ensure succession planning for its key leadership positions.

Nats chief executive Richard Everitt said: 'These appointments build on our intention to play a leading role in developing Europe's 'Single Sky' initiative, while ensuring that we continue to identify and develop the talent that will lead the company in the future.'

While there is uncertainty about how much consolidation will be required, European air traffic services will have to start work on integrating the numerous different IT systems.

Europe has a total of 41 air traffic control centres, compared with the 21 that cover the whole of the US.

The MEP responsible for steering the single sky legislation through EU Parliament, Dutch Liberal Democrat Marieke Sanders, says the legislation will benefit Europe as a whole.

Fewer airline delays, safer skies and reduced aircraft emissions are also among the advantages, but Sanders says this will take time.

'This is only the beginning of a long process towards improved air traffic management in Europe,' she said.

Part of Nats's upgrade plans include the installation of a new flight data processing (FDP) system following the consolidation of its four air traffic control centres to two.

Its Manchester and Scottish operations will be consolidated at the new Prestwick centre while the ageing London terminal control centre, currently at West Drayton, will move alongside London area control at Swanwick.

The Swanwick centre finally opened in January 2002, years late and significantly over budget.

Last November, Nats agreed a 14-month evaluation of an air traffic control system from its Spanish counterpart Aena, which it believes can be adapted for use by the UK.

If it goes ahead, Nats will launch the new system at its new Prestwick centre, which is due to become operational from 2009, and will then extend it to its Swanwick centre.

The system would also provide the platform for the next-generation FDP system, currently under development in a three-way collaboration between Aena, Nats and Germany's air traffic service provider, DFS.

Work on Nats' Prestwick centre only resumed recently after the project was suspended following September 11 and the subsequent fall-off in air traffic.