Ryanair can not rule out flight cancellations due to a planned cabin crew strike in Portugal during the Easter holidays.
But the airline expects that any disruptions will be small, its chief executive said at a news conference in Vienna today.
Portuguese union representatives have said the strikes are motivated by below-par labour conditions, including disciplinary processes and threats for not reaching in-flight sales objectives.
Asked whether there will by flight cancellations, Ryanair chief executive Michael O'Leary said: "It depends on how many disruptions there are. We can't rule it out but it will be small scale".
In a statement, the company said it had written to its cabin crew in Portugal urging them to put their customers first during this Easter Thursday and ignore the strike threat.
"This strike threat is entirely unnecessary given Ryanair has already sent the union a signed recognition agreement and agreed to meet with them on 9th April in Dublin," the airline added.
Michael O'Leary was in Vienna today to promote the airline's Laudamotion cooperation deal.
Ryanair has scheduled 90 flights to and from Portugal for Thursday, the CEO added.
Earlier, Laudamotion and Ryanair announced details of the Laudamotion summer 2018 schedule with a total of 21 aircraft operating from nine cities in Austria and Germany from June.
Last week, Laudamotion and Ryanair announced a new aviation partnership which sees Ryanair initially taking a 24.9% stake in Laudamotion, which will increase to 75% subject to approval by the EU Competition Authority.
The deal with Ryanair will allow the gradual growth of Laudamotion in Austria which currently has a fleet of ten Airbus aircraft.
Ryanair will provide financial and management support to Laudamotion as well as six wet-lease aircraft for summer to enable Laudamotion to complete its 21 aircraft flying programme from June.