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

Nats is investing up to £500m in upgrading its core IT systems to become more competitive as Europe moves to consolidate its air traffic control as part of the Single European Sky policy.

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

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

Many more system tests and upgrades are planned by Nats, raising the spectre of future problems and more flight delays as systems are modernised.

Europe has a total of 41 air traffic control centres, compared with the 21 that cover the whole of the US. Fewer airline delays, safer skies and reduced aircraft emissions are also among the touted advantages.

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

The Manchester and Scottish operations will be consolidated at the Prestwick centre, due to be operational in 2009, 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. Work on Nats' Prestwick centre only resumed recently after the project was suspended following the events of 11 September.