Cabin crew at Aer Lingus have voted overwhelmingly in favour of industrial action in a dispute over rosters, and the closure of the cabin crew base at Shannon.
However, the form or timing of any industrial action will not be announced today.
Cabin crew union IMPACT said the dispute centres on rostering problems and breaches of existing agreements.
Cabin crew are also angry at the Aer Lingus decision to close their Shannon cabin crew base.
Last month, Aer Lingus announced it was outsourcing recruitment for new transatlantic routes from Shannon to an independent company, ASL Aviation.
The airline blamed the decision on a refusal by cabin crew to fly new transatlantic flights from Shannon using smaller planes with only a four-strong crew rather than the usual higher number of staff.
As a result, the airline said it was closing down its cabin crew base at Shannon.
87 staff now face the prospect of redeployment to Dublin or Cork, voluntary severance, leave of absence to work for ASL Aviation, or redundancy - though the company has failed to specify whether redundancies could be compulsory.
In addition, 40 new jobs at Shannon will not now be created by Aer Lingus, though additional jobs could emerge through ASL Aviation.
IMPACT has said it remains available for negotiations and that it was not too late to reverse the decision.
A spokesperson for Aer Lingus said it had not received any notice of industrial action, and that they had no further comment to make at this point in time.
Meanwhile, management and unions remain deadlocked in a row over restructuring the company's pension scheme.
The scheme, which is shared with the Dublin Airport Authority, currently has a deficit of almost €800m - and unions want the two companies to make larger lump sum contributions to address the shortfall.
Unions have rejected the latest restructuring proposals from the scheme trustees, which they believe would result in significant cuts in pension benefits for serving and former staff who have not yet retired.