A 24-hour cabin crew strike has grounded half of Lufthansa's flights on Friday, a spokesman for the top German carrier said.
"On average, there are 1,800 Lufthansa flights during a normal day, around half of these flights will take place," he said after the start of the latest in a series of work stoppages in a dispute over pay and conditions.
"All German regions and all types of flights are affected," he said, including long-haul flights which in the past strikes have been the least disturbed by the stoppages.
Lufthansa's hub in Frankfurt, Europe's third-largest airport, "is strongly affected," he added.
The strike began at midnight (2200 GMT), but its effect overnight was minimal as there were no overnight flights scheduled.
The company had been expecting to cancel 1,200 flights, or two-thirds, as a result of Friday's strike.
On Thursday the carrier had cancelled around 50 flights ahead of the planned walkout by cabin crew at six major airports as the long-running dispute escalated.