German airline Lufthansa cancelled 40 flights on Friday because of a walkout by cabin crew at Frankfurt airport, an airline spokesman said.
The three-hour stoppage put out thousands of passengers
The Independent Organization of Flight Attendants said it called the three-hour stoppage to press demands for higher pay and improved working conditions.
Lufthansa said the cancellations affected short-haul and medium-range flights.
The stoppage by 400 flight attendants began at 6:15 a.m. and ended at 9:15 a.m.
The union, which represents 70 percent of Lufthansa's 16,000 cabin crew, is seeking a 15-percent pay hike over the next 12 months. Lufthansa has offered 10 percent, covering 14 months.
The union has refused to go along with a deal agreed between the airline and another cabin crew union, Verdi, for a lower pay rise.
On Wednesday, Lufthansa cancelled 15 flights because of a five-hour walkout by pilots of a regional partner airline, Contact Air, in a dispute over pay.