More than expected Ryanair passengers across Europe face travel disruption on Friday after strikes forced the airline to cancel 250 flights.
The total had stood at 150 until German pilots decided yesterday to walk out, resulting in another 100 cancellations.
They will join striking pilots in the Netherlands and Belgium.
Cabin crews in Belgium, Germany, Italy, the Netherlands, Portugal and Spain will also go on strike in a row over contracts and conditions.
Unions want staff to be given contracts in the countries where they live, rather than under Irish law.
Chief executive Michael O’Leary said the carrier had written to unions offering to move all staff to local contracts, which made the strike action “unnecessary”.
However, the Dutch pilots union said it had only verbally offered its members local contracts and had refused to put the offer in writing.
Joost Van Doesburg, of the VNV union, told the BBC his members also wanted pensions in line with Dutch standards, and firmer guarantees on sick pay.
Ryanair said the vast majority of its 2,400 flights today would be unaffected, with only 35,000 of 450,000 passengers facing disruption.
Passengers whose flight have been cancelled were contacted by email and text message on Tuesday to advise them of their options.
“We sincerely apologise to those customers affected by these unnecessary strikes on Friday which we have done our utmost to avoid,” Ryanair said.
The industrial action took the gloss off the airline announcing an extended reach from Manchester airport next summer with six new routes.
The addition of Bordeaux, Gothenburg, Marrakech, Marseille, Nantes and Thessaloniki will bring the carrier’s network from the north-west hub up to 63 routes with 350 weekly flights.
Passenger numbers from Manchester are set to grow by 6% over this year to 5.4 million.
The airport’s aviation director Julian Carr said: “It’s fantastic to see Ryanair adding yet more routes and continuing to grow from Manchester.
“Gothenburg and Marseilles are currently un-served from the airport and along with their other new routes will offer our 27.9 million passengers an even greater choice of destinations, whether it’s for business or leisure.”
More: Ryanair faces flak over latest round of strikes