Leaders of the 1,500 controllers yesterday warned that even minor disruption would cause havoc because the system is nearly at full capacity.
Iain Findlay, national official with the Institute of Professional Managerial Staffs union, yesterday declared that his members would not be "bought off" with a few thousand pounds worth of shares.
John Prescott, the Deputy Prime Minister, is expected to reveal that 6 per cent of the equity in the proposed public/private partnership would go to employees of the National Air Traffic Control Service. Mr Prescott is due to meet union representatives tomorrow before disclosing his strategy in the House of Commons. The sale is expected to raise pounds 500m.
Mr Findlay said that Mr Prescott had not fully consulted the union over the proposals, expected to involve the sale of 51 per cent of the equity to the private sector.
"If the Government proposes a genuine public/private partnership in which safety is protected then it would be a different story. But a couple of thousand pounds worth of shares won't buy us off, it is essential that safety comes before profits. The Government may come up with something that gives us that guarantee. However we are worried with what they are going to produce."
A motion threatening industrial action was agreed last Thursday. If the union presses ahead it would be the first walk out for 20 years.