It would cost over €70 million to relocate Sligo airport from its existing site in Strandhill, according to the chairman of the airport board.
However, opponents of the proposal to build an extension to the airport's existing runway say there must be a plan B in case planning permission for the extension is refused.
Both sides agree that if permission for the 259m extension is refused, the airport will be forced to close as it will not meet safety standards.
Sligo County Council had been due to make its decision on the planning application by November 1st, but has sought additional information from the airport.
This week Sligo county councillors rejected a motion urging the board to seek funding for a consultants' report on the feasibility of moving the airport to a greenfield site.
One of those who voted against the motion was Fianna Fáil councillor Albert Higgins, chairman of the airport board, who said the move was not feasible and information supplied to him suggested it would cost €53 million to move the airport and at least €20 million more for a 200-acre site.
Cllr Higgins said it would be a nonsense to seek such funding for an airport that would be 45 minutes from the international airport at Knock.
Independent councillor Declan Bree, who proposed the motion calling for a feasibility study, said the great majority of local people did not want the runway extended on to Dorrins strand, which is in a special area of conservation.
Cllr Bree said, given the strong possibility planning permission may be refused, an alternative site must be considered. He said it would be a "disaster" for Sligo if the airport was forced to close.
John McDermott, chairman of the Dorrins & Cummeen Strand Conservation Group, urged the board to revisit the issue of an alternative site.
The group is opposed to the runway extension because of the potential impact on the beach and on the local shellfish industry. Fears have also been expressed about the effect on wildlife, particularly birds, including Brent geese, and on access to nearby Coney island. "No-one can say what the cost of relocation would be without such a feasibility study," said Mr McDermott, who said he was prepared to work with the airport on the issue.
