SIPTU has warned of industrial action at Aer Lingus in the coming weeks.
It comes after talks with the union on the company's cost-cutting plans broke down at the Labour Relations Commission yesterday evening.
Management at the airline says it is proceeding with plans to cut 1,300 jobs by outsourcing ground operations.
Speaking on RTÉ Radio's Morning Ireland, SIPTU National Industrial Secretary Gerry McCormack said the union still wanted to try to resolve the issue through other avenues, but the company could force their hand.
Meanwhile, IMPACT union officials will meet management at Aer Lingus today to discuss the issue of cabin crews.
The company wants to use US crews on its transatlantic routes.
The airline is seeking cost savings of €74m.
SIPTU has warned that if Aer Lingus proceeds unilaterally with outsourcing, the union will in turn proceed with industrial action.
The airline wants to implement its controversial cost cuts on 1 December.
For four weeks, the LRC has tried to broker a deal on alternative ways of securing the savings, but those talks have now collapsed.
Aer Lingus accused SIPTU of failing to engage in any meaningful way to address the cost base, adding that it cannot afford further losses in 2009.
It has received proposals from outsourcing suppliers, and will select a preferred supplier by the end of next week, and then proceed to conclude contracts.
Staff will be advised of their redundancy options over the next fortnight.
