Ryanair plans to cancel 250 flights in and out of Germany on Friday after pilots joined a 24-hour walkout taking place in Ireland, Sweden and Belgium.
The airline, which has been struggling to agree terms with pilots and cabin crew in many of the markets it operates in, has already cancelled 146 flights in the three other countries.
Ryanair chief marketing officer Kenny Jacobs said the firm regretted the decision taken by the pilots’ union and was ready to continue negotiations.
“Our pilots in Germany enjoy excellent working condition,” Mr Jacobs said.
“They are paid up to €190,000 (£169,948) per annum and, as well as additional benefits, they received a 20% pay increase at the start of this year.
“Ryanair pilots earn at least 30% more than Eurowings and 20% more than Norwegian pilots.”
The carrier said it would contact the affected customers and provided them with alternative flights or refunds.
Europe’s biggest airline by passenger numbers operates more than 2,400 flights across Europe each day.
It had to cancel more than 600 flights last month after disgruntled staff in Belgium, Spain and Portugal went on strike.
Martin Locher, the president of German pilots’ union Vereinigung Cockpit (VC), said: “We hope that the strike will lead Ryanair to say they are ready to compromise with us and enter serious negotiations”.
German pilots are unhappy with their variable salaries and Ryanair’s practice of moving crews between bases without notice.
“Pilots are not nomads who put up tents wherever Ryanair wants to operate,” VC negotiator Ingolf Schumacher said.
Ryanair has threatened to shift jobs if the walkout hurts its business.
It has already warned its Irish pilots and crews that it could axe 300 jobs if strikes continue.
“Improvements are not possible without an increase in staff costs in the cockpit,” Mr Locher said.
“At the same time, Ryanair has not yet said where there might be room for manoeuvre.”
Ryanair was forced to recognise unions last year after a rota blunder caused the carrier to cancel flights, affecting more than 700,000 passengers.