Lufthansa, the leading German airline, faces a major strike next week after members of the German trade union Verdi voted on Friday for a strike to press demands for higher wages.
Ground personnel and flight crews would stop working on Sunday at midnight (2200 GMT), the union said after its members approved the action by an overwhelming majority of 90.7 percent.
Lufthansa, which transports 150,000 passengers daily, expressed "incomprehension" at the announcement, but an airline spokeswoman added that it was "ready to talk" with union representatives.
It was not immediately clear however how widespread the strike might be in initial stages, though Lufthansa's hubs in Frankfurt, Munich and Duesseldorf were among 11 airports that faced early disruptions.
Verdi negotiator Erhard Ott said there would not be a blanket paralysis of German airports to start with, but that all would be affected at some point next week.
He promised "major disruptions" and called on passengers who were set to take summer holidays to show understanding with his union's members.
"We are aware that we are going to cause big problems for passengers," Ott said.
Lufthansa was working on a back-up plan according to its spokeswoman, but uncertainty over the movement's scope and a lack of details on how the strike would take place complicated the airline's task.
"The management has closed the door to all talks for the moment," Ott told a press conference in Berlin.
Verdi is seeking a 9.8 percent pay raise over a year for some 50,000 workers, while the German flag carrier has offered 6.7 percent over 21 months.
Lufthansa made an operating profit last year of 1.38 billion euros (2.2 billion dollars), a figure it expects to reach again in 2008, despite stiff competition and rising fuel costs.
Airline boss Wolfgang Mayrhuber said in a letter to Lufthansa staff that "we cannot do any more" than the offers that are already on the table, owing to "extremely limited economic room to manoeuvre."
But Verdi said it was not ready to resume talks until the airline made "a much better offer," Ott said.
Lufthansa is also stuck in a pay dispute with pilots of two subsidiaries, CityLine and Eurowings, who have staged warning strikes that grounded some 1,000 flights this week.
