By Maria Sheahan and Peter Maushagen
FRANKFURT (Reuters) - Pilots at Deutsche Lufthansa AG
The strike, the ninth this year in a dispute over an early retirement scheme, has forced Germany's flagship airline to cancel close to half of all scheduled flights for Monday and Tuesday, affecting about 150,000 passengers.
"We cannot keep doing this for the next year or two, we need to sit down and find a solution," Lufthansa spokeswoman Barbara Schaedler told Reuters TV.
Pilots however showed no sign of backing down, with pilots' union Vereinigung Cockpit (VC) board member Joerg Handwerg telling Reuters it could continue its walkouts into next year.
Lufthansa is trying to squeeze its cost base to compete with low-cost carriers like Ryanair Plc
VC, representing about 5,400 Lufthansa pilots, is fighting to retain a scheme allowing pilots to retire at 55 and still receive up to 60 percent of their pay before regular pension payments start at 65.
Lufthansa has said it would not accept a demand that new pilots, as well as those already with the company, should be able to retire at 55.
In the meantime the stoppage is causing frustration among customers. "We only found out about the strike in Germany just before departing Chicago," said Paula Herman, 47, part of a group travelling from the United States to Israel.
"(The pilots) are totally messing up other people's plans. Our trip to Israel is once-in-a-lifetime," she told Reuters at Germany's busiest airport, Frankfurt.
Under European Union law, pilots may legally fly until they are 65 but many airlines offer early retirement options. According to VC, pilots at British Airways, part of International Consolidated Airlines Group SA
Industrial action in the dispute has already wiped 160 million euros ($200 million) off Lufthansa's operating profit and the airline lowered its profit guidance for 2015 for a second time in October, ratcheting up the pressure to put the row with pilots to rest.
The Germany-wide strike is to last until 2259 GMT. Lufthansa said it would be able to operate all scheduled cargo flights despite the strike. Budget carrier Germanwings is not affected.
(Additional reporting by Victoria Bryan and Reuters TV; Editing by Kenneth Maxwell and David Holmes)