On behalf of 3,000 air traffic controllers, engineers and specialists at NATS, Garry Graham, Prospect’s National Secretary for Aviation, said:

“We have been consistent in warning that this is a route which the UK Government should not go down. Air traffic control is a vital part of this country’s infrastructure.

“A safe, efficient and effective air traffic control system is of crucial interest, not only to the UK economy, but also to every member of the travelling public.This proposed sale has nothing to do with supporting a safe and effective air traffic control system and is entirely Treasury driven.”

He said the union had written to the Secretary of State for Transport, Philip Hammond, seeking an urgent meeting on this issue, but had yet to receive a reply despite a pre- election commitment from David Cameron that Prospect would be consulted prior to any announcement.

“The Government’s proposals are short-sighted and represent a knee-jerk reaction by the Treasury. NATS receives no public subsidy, is a net contributor to the Exchequer and provides an invaluable public service.

“No other country has gone down this route – ironically, Germany has recently rejected proposals to go down the route of privatisation. Stability, sustainability and safety should be the key Government concerns – air traffic control is too important to be left to the vagaries of the market.

"The UK has some of the most congested and complex airspace in the world and it is a tribute to the professionalism and hard work of our members that it is also some of the safest.”

Prospect is seeking urgent meetings with Ministers to set out its members’ concerns and resist any proposed Government sale.

NATS was part-privatised in 2001. At present the Government retains a 49% share, the Airline Group – a consortium of airlines – has a 42% holding, BAA has a 4% shareholding while the remaining 5% of shares are held by staff.