Some Dublin-based Ryanair pilots are to strike before Christmas in a dispute about union recognition and better conditions.
Ryanair passengers face disruption to their Christmas travel plans after pilots and crew announced industrial action in a bid to win union recognition and better conditions.
The 79 pilots, who are directly employed by Ryanair, will walk out for one day on 20 December.
In Ireland, 79 pilots based in Dublin will strike for one day on 20 December.
It involves mostly captains who are members of the Irish Air Line Pilots' Association (IALPA).
The airline, which does not recognise unions, said they represented about 28% of its Dublin-based captains.
Ryanair, which does not recognise trade unions, said they represented less than 28% of its Dublin pilots.
Ryanair pilots and cabin crew in Germany, Italy and Portugal also plan action.
It has warned them that they will lose favourable rosters and remuneration benefits if the action goes ahead.
Cockpit, the German pilots' union, said its Ryanair members would strike for better pay and conditions if Ryanair failed to begin talks, but vowed not to disrupt flights over Christmas.
In a statement, the carrier said: "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.
Ryanair said it would "not deal with or recognise" the German union "regardless of what action - if any - takes place".
"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."
Unions have long argued that their airline fails to offer pilots the same pay and conditions as its rivals.
IALPA is a branch of the Irish umbrella trade union, IMPACT, which is predicting either flight disruptions or substantial costs to the airline.
Impact, the Irish pilots' union, said the dispute was "solely about winning independent representation for pilots in the company", said official Ashley Connolly.
The German pilots' union, Vereinigung Cockpit, has also threatened strike action against the Irish carrier as it also pushes for a collective labour agreement.
Ryanair rejects union representation saying it prefers to negotiate with staff directly.
The budget airline suffered a difficult period earlier this year when it cancelled flights between September and March after mismanaging pilots' annual leave, affecting around 700,000 passengers.
