Lufthansa cancelled hundreds of flights for Tuesday at Germany's largest airports in anticipation of warning strikes by ground handlers in a dispute over pay.
Ground handlers in Frankfurt, the country's biggest hub, would strike from 0300 to 1230 GMT in a walkout organised by German services union Verdi, the airline said in a statement on Monday.
"Flight traffic is likely to be considerably affected and include cancellations," added a spokesman for Frankfurt airport operator Fraport.
Lufthansa, which operates about 1,850 flights on a typical day, said it cancelled about 400 of its flights planned for Tuesday.
Air Berlin planned to cancel eight flights out of several hundred, an Air Berlin spokeswoman said.
Munich airport would be affected by the strike from 0400 to 1200 GMT, Düsseldorf from 0600 to 1200 GMT, Cologne from 0200 to 1000 GMT and Stuttgart from 0400 to 0900 GMT.
Verdi warned that the strike times could change and said smaller airports, such as Dortmund, Hanover and Bremen, would also experience work stoppages on Tuesday.
If warning strikes were not sufficient to get a pay deal moving, the union could take a tougher line in the coming weeks, Verdi head Frank Bsirske said on Monday.
"The chances are 50-50 for a full-scale strike," he said.
If the union and employers fail to agree in talks this week, the dispute could go to mediation. Should mediation fail, the union could ballot its members on a broader strike in the second half of April, Bsirske said.
Verdi is pushing for a 6.5 percent pay rise for around 2 million federal and local public sector workers, and at least EUR€200 more per month.
Employers have offered a 3.3 percent rise over a period of 24 months and a one-off payment.
Gravity always wins!