The Government wants to ensure that any new owner of Aer Lingus retains the company's name and brand, together with the airline's landing slots at Heathrow. The move is intended to ensure the company's Irish identity will be maintained.
Government sources said last night they were looking at several ways this might be done. Any attempt to put conditions on the sale would reduce the airline's value, but the Government may be prepared to accept a reduced value for assurances on various issues.
The sale of the airline - most likely via a stockmarket flotation - is viewed positively by the markets, but there is concern over a number of issues.
One of these is the restrictive nature of the bilateral agreement between the US and the Republic which confines Aer Lingus to just five US airports.
Another issue concerning some analysts is the deficit in the company's pension scheme, which is shared with the Dublin Airport Authority. This is believed to be about €243 million.
The sale is unlikely to take place until early next year at the earliest, the chairman of the airline, John Sharman, told The Irish Times last night.
He said that while the timetable was ultimately a matter for the Government, it would probably take advisers some time to complete their work on what was the best method of selling the airline. He said the airline's new chief executive, Dermot Mannion, would not be starting until August.
He added that serious issues concerning changes in work practices would also need to be addressed. Mr Sharman said he was determined the airline would keep the valuable slots at Heathrow.
He said Dublin-Heathrow was a core route and while he was chairman nothing would be done to undermine that route.
Asked would the Government be able to insist on this, he said: "I would have thought they would be able to do that. But I have no intention of withdrawing from Heathrow that's for sure," he said.
Minister for Transport Martin Cullen yesterday briefed the chairmen of the Dublin Airport Authority (DAA) and Aer Lingus, the DAA chief executive and incoming Aer Lingus chief executive, Mr Mannion.
The Government has not said what proportion of the airline it will retain, although Mr Cullen said on Wednesday that it would be "at least 25 per cent".
Taking into account the airline workers' 14.9 per cent stake, the maximum that can be sold is therefore 60 per cent.
While further "rights issues" of shares in the coming years to secure yet more capital could further dilute the State's share, Taoiseach Mr Ahern said yesterday that he could not envisage a situation in which the State would not stay involved in Aer Lingus.
The Department of Transport plans to place advertisements in the national press next week for financial advisers to help the Government decide what proportion of the national airline to sell, and by what method to conduct the sale.
Mr Ahern also warned that work practices at the airport would have to change in conjunction with the development of the second terminal. "If all the old practices that were there were just continued on, clearly you would find that it would not be an attractive proposition.
"The new terminal will have to take into account - and this is understood by the trade union movement very clearly - it's going to have to be a different kind of work practices, different kind of flexibilities, than are in the present arrangement. That has been clear from the start."
Tánaiste Ms Harney said yesterday that "in an ideal world" she would have preferred a different option. "But we don't live in an ideal world. We have a Coalition Government, we have to have give and take and I think there was a lot of give and take in relation to this issue.
"It's a question of a compromise deal in the interests of Coalition Government, partnership government."
Businessman Ulick McEvaddy, who has been campaigning to build a new terminal, said last night that he would lodge a complaint "within days" against the Government under national and EU competition law.