Ireland's high court on Wednesday granted Ryanair an injunction to prevent its Dublin-based pilots from going on strike this week.
It's a setback to union hopes for a wave of industrial action against Europe's biggest budget airline.
Separately, a five-day strike by Ryanair's cabin crew in Portugal got underway.
But disruption to passengers appeared minimal, with no canceled flights or major delays so far.
A UK court is due to rule later on Wednesday whether Ryanair's British pilots can go ahead with their planned strike on Thursday -- the same day as the proposed action in Ireland.
Ryanair's battling to contain a wave of unrest among workers around a year after strikes over pay and conditions forced the Irish airlines to cancel hundreds of flights.
The company welcomed the Irish court ruling, saying all flights scheduled to depart on Aug.
22 and 23 from Irish airports would operate as normal.