Dublin Airport Authority in court over SIPTU industrial action
The High Court in Dublin is due to hear an application from Dublin Airport Authority (DAA) and Ryanair to prevent SIPTU from taking industrial action.
SIPTU workers at DAA and Aer Lingus are due to go on a four-hour strike on Friday over changes to their pensions.
The union issued a strike notice after talks aimed at resolving the dispute broke down.
Both DAA and Aer Lingus are making contingency plans.
Aer Lingus staff are opposed to changes being made to their pensions without their consent.
DAA staff also face pension reform.
SIPTU last month served notice of industrial action at Aer Lingus, the Dublin Airport Authority and the Shannon Airport Authority.
The strike is due to begin at 05:00 GMT to 09:00 GMT on 14 March at Dublin, Cork and Shannon airports.
An expert panel has been appointed to investigate the long-running dispute over threatened benefit cuts in the joint aviation pension scheme.
It is due to issue a preliminary report at the end of March.
The dispute centres on a 750m euros (£618m) deficit in the pension scheme that covers staff at the airline and the DAA.