The work, it warned, is essential in order to modernise the existing radar systems and cope with the projected air traffic growth over the next five years.

Marching in support of the `Freedom to Fly` campaign, Prospect’s aviation officer, David Luxton, said: "There can be no excuse for further delay in starting work on designing and building a new state-of-the-art air traffic centre at Prestwick.

"The current Scottish area control centre (ScOACC) is using outdated technology and is not in a position to cope with the huge increase in flights in the UK expected over the next five to ten years.

"National Air Traffic Services gave a commitment to a new Scottish centre as part of its licence to operate, agreed under the public private partnership last year. But it is now clear that the government, one of the main shareholders in NATS, is having second thoughts about the project primarily on cost grounds.

"Moves to build a third runway at Heathrow will be futile without sufficient capacity in the air traffic control infrastructure to manage extra flights. Further delay to the Prestwick project will impact on the ability to handle increased air traffic because of the pressures on the current capacity at the existing Scottish centre."

The new Scottish control centre is intended to replace existing centres at Manchester and Prestwick. Air traffic controllers and air traffic engineers represented by Prospect will be joining the `Freedom to Fly` lobby of Parliament today at 1.30pm outside St Stephen’s entrance.