In response to unions serving Ryanair strike notices, Europe's largest low-priced carrier has announced in recent days the cancellations of 250 flights in and out 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.
A Dutch court on Thursday evening rejected a case from Ryanair seeking to block pilots in the Netherlands from joining the strike, affecting about 22 flights.
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.
The VNV said it has been negotating with Ryanair over a pay-and-conditions agreement for eight months without making any progress.
That topped the 300 flights a day it had to cancel last month when cabin crews in Belgium, Portugal and Spain escalated the staff revolt by going on strike for 48 hours.
A spokesman said that despite the walkouts, 85% of Ryanair's scheduled flights, more than 2,000, would operate as normal.
Ryanair, which flies in 37 countries and carried 130million people last year, averted widespread Christmas strikes last year by agreeing to recognise trade unions for the first time in its 33-year history.
Another customer said she would miss work meetings and a doctor's appointment due to a cancelled flight.
Since then, however, it has struggled to reach agreements.
Staff are holding a 24-hour walkout over pay and conditions.
Kenny Jacobs, the chief marketing officer at Ryanair, said recently that the airline was "not prepared to concede to unreasonable demands that will compromise either our low fares or our highly efficient model".
"They tweeted: "#ryanair cancelled my flight in the last min because of pilots strike.
Ryanair has repeatedly said it remained open to further talks with pilot representatives.
Peter Scherrer, deputy secretary general of the European Trade Union Confederation, said he welcomed today's cross-border show of unity by pilots.
It said it has taken every step to minimise the disruption, adding: "The majority of customers affected have already been re-accommodated on another Ryanair flight".
'We want to again apologise to customers affected by this unnecessary disruption and we ask the striking unions to continue negotiations instead of calling any more unjustified strikes'.