A legal bid to stop strike action at the main Irish airports in the run up to St. Patrick's Day is due before the High Court. The Dublin Airport Authority (DAA) and Ryanair are trying to secure an injunction against SIPTU.
SIPTU is planning a four-hour work stoppage at Dublin, Cork and Shannon airports this Friday. Strike action is due to take place between 5am and 9am.
It is part of a long-running dispute about cuts to pension benefits at Aer Lingus and the DAA.
That scheme was closed for new entrants in 2009 with several hundred other members not included in the vote.
SIPTU sources say the union will defend its position at the hearing today.
However, the DAA and Ryanair claim the strike is unlawful and they want injunctions stopping the industrial action which coincides with the France v Ireland rugby match and the busy run-up to St Patrick's Day.
Ryanair says if the action does go ahead, it would affect 13,500 of its customers.
The Irish Times Industry Correspondent Martin Wall said that the DAA will also be targeting a 'no strike clause' it claims it has with security and fire staff.