Workers at Dublin, Cork and Shannon airports have begun a campaign against the shake-up of Aer Rianta planned by the Minister for Transport, Mr Brennan.
They claimed yesterday that hundreds of jobs will be lost if the Minister proceeds with a break- up of the company and allows an independent terminal to be built at Dublin Airport.
About 250 workers from a number of unions attended a general meeting organised by SIPTU at the airport to voice their concerns.
Staff representatives from Shannon and Cork also attended, at which it was agreed not to take industrial action in the immediate future.
Instead, business leaders and politicians are to be lobbied about what unions claim will be the social and economic costs if the Minister's reforms go through.
Mr Brennan is to take proposals to the Cabinet within the next few weeks, following a series of meetings with Aer Rianta management and staff.
He has said he supports the idea of a private terminal at Dublin Airport, acting in competition with the existing Aer Rianta facility.
He also favours breaking the company into separate entities to enable the three airports to compete with each other for business.
Mr Dermot O'Loughlin, secretary of SIPTU's civil aviation branch, said a private terminal at Dublin Airport would have a "huge impact" on the quantity and quality of jobs.
Aer Lingus and Ryanair currently had 83 per cent of the airport's business between them, he said. If either moved to a new terminal there would inevitably be job losses, and nobody would build the new facility without a guarantee of at least one significant customer.
A series of economic reports, he added, had indicated that airport charges would increase if the proposals went through. This, in turn, would lead to higher air fares. He also claimed the value of Aer Rianta would collapse, leaving the taxpayer to pick up the bill.
Industrial action, he said, was an option the unions should keep in their "back pockets".
The branch president, Mr Barry Nevin, claimed up to half the jobs in Aer Rianta could be lost if the Minister proceeded with his plans.
A spokesman for Mr Brennan, however, said there was no threat to jobs. The Minister proposed to expand the market rather than reduce it, and a new terminal would need people to work in it.
It was also Mr Brennan's view, he said, that Cork and Shannon airports had a better chance of thriving if given greater independence.
Strong support for a retention of the Shannon stopover, which requires that half of all flights between the Republic and the US stop at Shannon, was also expressed at the SIPTU meeting.
Mr Brennan has indicated he will facilitate moves at EU level to end the stopover in return for increased EU aid for the Shannon region.
Mr Pat Fitzgerald, an Aer Rianta worker director who travelled from Shannon for the meeting, said the stopover was "the lifeblood" of the region.
An independent terminal in Dublin, he added, would have a detrimental effect on all three airports.
"Every one of you should write to your TDs and point out the nonsense of what's going on."
