Ryanair is facing the most disruptive days of industrial unrest in its history as Dutch pilots today join their colleagues in Ireland, Sweden, Germany and Belgium in strikes affecting tens of thousands of travellers.
Dozens of Ryanair flights into and out of United Kingdom will not take place as scheduled on Friday as a result of a strike by pilots in Europe.
The action is the largest in a series of strikes over pay and conditions.
Nearly 400 flights have been grounded across Europe, with that figure set to rise sharply with pilots in the Netherlands deciding to join the walkout yesterday.
An estimated 50,000 passengers are understood to have been informed of cancellations, the majority of whom have been re-accommodated on alternative flights.
Ryanair slammed the strike as "unnecessary".
A spokesman said that despite the walkouts, 85% of Ryanair's scheduled flights, more than 2,000, would operate as normal.
Since the it first recognised unions in December 2017, walkouts have been staged multiple times by Ryanair staff in various countries.
A total of around 400 flights Europewide have been cancelled due to the strike action, AFP reported - equating to around 55,000 passengers.
Spanish pilots union Sepla announced it is taking action against the Irish airline in Spain's High Court over its pilot contracts last week.
Ryanair is bracing for its biggest-ever one-day strike on Friday with pilots based in five European countries set to walk out, forcing the cancellation of about one in six of its daily flights at the height of the holiday season.
Ryanair operates more than 2,000 flights a day, serving 223 airports across 37 countries in Europe and North Africa, and insists it will not change the low-priced model that transformed the industry and has made it Europe's most profitable airline.