Ryanair pilots based in Ireland will be striking on Wednesday of next week, the Guardian reports.
This walkout is expected to affect flights to and from Dublin, Shannon, and Cork.
The strike is being called in order to win collective representation in pay deals, instead of through Ryanair's employee channels.
The airline has said it will 'face down' the strike, in spite of the fact that some 'disruption may occur' as a result.
Ryanair claims that the number of pilots taking action is less than a third of those that they employ in Ireland.
The Irish Air Line Pilots' Association (IALPA) union disagreed, saying that the 117 pilots expected to take part in the strike make up almost 90 percent of the pilots directly employed by Ryanair in Ireland.
The IALPA, which are part of the Republic's second-largest trade union, Impact, also said that most of those 117 pilots are captains, who are needed on every flight.
They say the walkout will either cause major disruption or will greatly cost the airline if they bring in pilots from other European bases.
The situation is not unique to Ireland. Ryanair crew and pilots in Italy are striking on Friday, and in Portugal, pilots voted to strike. Ryanair fought back by telling cabin crew in Italy that if anyone strikes, their whole base will lose rights to transfers or promotions.
A statement by the airline says, "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 percent of our Dublin pilots may cause them over the coming days."
They continued. "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 unions."
Ryanair has told their pilots that if they take action they will be in breach of their agreements, which means they will lose benefits such as guarantees over rosters and pay, as well as promotion opportunities. The airline says they offered 20 percent pay deals to their pilots.
Impact stated that the walkout is 'solely about winning independent representation for pilots in the company', as Ryanair is the only Irish-based airline that does not recognise the unions.
Union official Ashley Connolly said, "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 union says that more strikes could follow.
