High Court proceedings aimed at preventing Friday's proposed strike by Siptu members at the country's airports start this morning.
The proposed industrial action, involving four-hour stoppages at Dublin, Cork and Shannon on Friday 14th March, arises from the long-running dispute over cuts in pension benefits at Aer Lingus and the DAA.
In proceedings against Siptu, Ryanair and the DAA want the High Court to grant injunctions preventing the proposed strike going ahead.
The applications are being opposed by the trade union.
This morning the matter opened before Mr Justice Paul Gilligan at the High Court.
The judge was told by lawyers for the various parties that the hearing of the injunction applications will be completed within the day.
Last week both Ryanair and the DAA separately secured leave to serve short notice of their proceedings against Siptu.
Both the DAA and Ryanair claim the proposed strike would result in Dublin airport being shut down during one of the busiest weekends of the year.
Friday is the start of the St Patrick's holiday weekend and also coincides with the Ireland/France rugby match and the Cheltenham horse racing festival.
Union members at both Aer Lingus and the DAA voted for industrial action last month over a € 780 million deficit in the Irish Airlines Superannuation Scheme (IASS), a pension scheme jointly operated by Aer Lingus and the DAA.
After separate negotiations between unions, the DAA, and Aer Lingus ended without a resolution late last month, Siptu notified the DAA, Cork and Shannon airports and Aer Lingus that its members planned to stop work between 5am and 9am on March 14th.
The planned action would ground flights and lead to closure of the airports as staff in critical services are union members.
Aer Lingus has released a list of cancelled and disrupted flights in response to the planned strike.
The airline has hired in aircraft, rescheduled flights and rebooked ticket holders onto different carriers in the event of the strike going ahead.
Flights affected include Boston, London, Brussels, Frankfurt, Amsterdam, Milan and Paris.
Customers whose flights have been cancelled or rescheduled by more than three hours can apply for a refund or change their flight free of charge, the airline said.
To see the revised list of flights click here