Aer Lingus has invited unions to a meeting on Thursday in a bid to avert strike action at the country's airports during the St. Patrick's Day celebrations.
SIPTU has warned Aer Lingus that a strike at the airline is now "highly probable".
Earlier, Minister for Transport, Leo Varadkar called on SIPTU members at Aer Lingus and the DAA not to go ahead with the action.
The dispute centres on a deficit in the pension fund operated by Aer Lingus and the DAA. Two separate rounds of talks take place this week on both Wednesday and Thursday.
"In fairness, the DAA do appear to be closer to meaningful talks which begin on Wednesday," said Dermot O Loughlin of SIPTU.
"But unfortunately, the Aer Lingus side … they do not want to appear to answer some of the critical questions … which causes many a problem."