SIPTU says a strike at Aer Lingus is now highly likely - and could impact thousands of passengers coming to Ireland for St Patrick's Day.
The union and the airline have been involved in a row over a massive deficit in the pension fund run by the airline and Dublin Airport Authority.
Aer Lingus has appealed for the union to pull back from the threat of industrial action - which it says won't solve the row.
Richard Chambers reports: