The High Court will hear an application from Ryanair on Monday seeking a court order to prevent a strike by pilots next week.
180 Irish-based pilots are due to walk off the job for two days in a row over pay.
Talks between Fórsa and Ryanair this week, aimed at averting the industrial action next Thursday and Friday, ended without a resolution.
Today, lawyers for Ryanair made an application to the High Court for an injunction to stop the strikes going ahead.
They say the Irish Airline Pilots Association (IALPA), whose parent union is Fórsa, withdrew from the mediation talks before they got going.
And that Ryanair still doesn't know the exact detail of what the pilots want.
Counsel for Ryanair told the court that the proposed strikes would breach an agreement both parties signed up to last year.
The airline's lawyer also claims the timing right in the middle of school holidays is aimed at causing maximum disruption to passengers.
Ms Justice Carmel Stewart has allowed Ryanair to serve notice of its proceedings against the union.
Reporting from Stephen Murphy at the High Court