Lufthansa flight attendants went on a 48-hour strike over pay and pensions on Thursday, forcing the biggest German airline to cancel hundreds of flights.
Lufthansa on Wednesday announced it expected to cancel a total of 1,300 connections on Thursday and Friday, with 180,000 passengers affected. That amounts to about one in five of Lufthansa's planned 6,000 flights over the two-day period.
The departure table on Frankfurt airport's website showed scores of cancelled flights to European destinations and on transatlantic routes.
A Lufthansa spokesman confirmed about 400 flights would be cancelled in Frankfurt alone on Thursday, with an additional 250 in Munich and some more at smaller airports, bringing the total number to 700 on Thursday.
"It's quiet in the terminals," a spokeswoman for Frankfurt airport said, adding that many passengers had rebooked onto different flights and not shown up at the airport.
Flight attendants' union UFO has left open the possibility of continuing the strikes beyond Friday, potentially escalating the dispute.
The airline and the union have been at odds for months over the union's legal status. Lufthansa says the union leadership team that took office earlier this year was not elected in a way that met legal requirements -- a stance that UFO contests.
Lufthansa CEO Carsten Spohr on Thursday announced new talks with unions including UFO.
Lufthansa, which faces tough competition from Ryanair and easyJet, on Thursday also announced plans to cut costs at its Austrian Airlines, Brussels Airlines and Lufthansa Cargo units to revive profits.