Ireland-based Ryanair pilots to strike five days before Christmas
Some Irish-based Ryanair pilots are to take pre-Christmas strike action.
The one-day industrial action will take place on Wednesday December 20 and will mostly involve captains.
Trade union Impact said it would either disrupt flights or generate substantial costs for the airline.
Pilots from the Irish Airline Pilots' Association backed the industrial action overwhelmingly during secret ballots.
The dispute is about winning independent representation for pilots in the company, Impact said.
Although the number of employees involved in the strike is fewer than the total number of Irish-based Ryanair pilots, the action will have impact because planes cannot legally or safely fly without a captain, the union added.
Impact official Ashley Connolly said Ryanair was the only Irish-based airline that refuses to recognise independent pilot representatives.
"This dispute is solely about winning independent representation for pilots in the company.
"Management's failed negotiating model has let down shareholders and tens of thousands of passengers, whose flights were cancelled this year because company-controlled industrial relations proved incapable of recruiting and retaining enough pilots.
"The failed policy threatens to further disappoint shareholders and passengers, and further damage the airline's reputation, because experienced pilots continue to leave the airline in droves.
"This dispute is about securing a safe space for negotiations, with independent representation that pilots can have confidence in."
The action relates to 79 pilots directly employed by Ryanair, less than 28% of its Dublin workforce.
An airline statement said: "Ryanair will deal with any such disruptions if or when they arise, and we apologise sincerely to customers for any upset or worry this threatened action by less than 28% of our Dublin pilots may cause them over the coming days.
"Ryanair is surprised that IALPA has threatened to disrupt Christmas week travel when IALPA's own numbers confirm that it has the support of less than 28% of Ryanair's over 300 Dublin pilots and when Ryanair's Belfast, Cork and Shannon bases have already agreed these 20% pay deals.
"While some disruption may occur, Ryanair believes this will largely be confined to a small group of pilots who are working their notice and will shortly leave Ryanair, so they don't care how much upset they cause colleagues or customers."
Ryanair has already confirmed that any Dublin pilots who participate in this industrial action will be in breach of the Dublin pilots base agreement, the statement said.
It warned they will lose agreed benefits which arise from dealing directly with Ryanair, including the five-day on, four-off rosters, and certain pay benefits and promotion opportunities until such time as they chose to return to the 25-year established practice of dealing directly with the airline.
The statement said: "Like any group of workers, Ryanair's very well paid pilots are free to join unions, but like every other multinational, Ryanair is also free - under both Irish and EU law - to decline to engage with (competitor pilot) unions.
"Ryanair will not recognise an Aer Lingus pilot union, no matter how often or how long this tiny minority (earning between 150,000 to 190,000 euro p.a.) try to disrupt our flights or our customers' plans during Christmas week."
The budget airline suffered a turbulent period earlier this year when it cancelled flights between September and March after mismanaging pilots' annual leave, affecting around 700,000 passengers.