Hundreds of Ryanair flights - including at least 50 services into and out of Britain - will not take off as planned today due to pilot strikes in five countries.
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.
In response to unions serving strike notices, Ryanair had announced the cancellations of 250 flights in and out of Germany, 104 to and from Belgium and another 42 in Sweden and its home market of Ireland, where around a quarter of its pilots were staging their fifth 24-hour walkout.
Today's unprecedented simultaneous strike action by Ryanair pilots is the latest headache in a turbulent summer for Europe's second-largest airline.More news: 'FIRENADO' captured in Derbyshire
Ryanair has refused to issue a list of the flights cancelled, but The Times understands that at least 50 departures from the United Kingdom have been called off, with more than 250 cancelled in Ireland.
The Irish airline, Europe's largest low-priced carrier, averted widespread strikes before Christmas by agreeing to recognise unions for the first time in its 30-year history.
"What I find unjustified is that the pilots draw the short straw, because people want to fly cheaply", said Daniel Flamman, one of several passengers Reuters spoke to at Frankfurt airport who said they sympathised with the pilots.
Ryanair claimed more than 2,000 flights would operate as normal on Friday. Irish pilots recently staged four one-day walkouts, while cabin crew in Spain, Belgium, Italy and Portugal went on strike on July 25 and 26.More news: United States to impose sanctions on Russian Federation over attack on Skripals
A statement from CEO Michael O'Leary said: "Ryanair fully complies with all EU261 legislation, however as these flight cancellations were caused by extraordinary circumstances, no compensation is due". This can mean staff based in other European states are unable to gain access to state benefits.
He added that Ryanair had already offered a 20% pay increase this year, and that 80% of its pilots in Germany were now on permanent contracts.
Peter Scherrer, deputy secretary general of the European Trade Union Confederation, said he welcomed today's cross-border show of unity by pilots.
"The majority of customers have already been accommodated on another Ryanair flight".More news: New York Yankees: Is the American League East race over?
"We want to apologise to customers affected by this unnecessary disruption and we ask the striking unions to continue negotiations instead of calling anymore unjustified strikes [sic]".