German airline Lufthansa is canceling 1,000 flights on Wednesday because of a pilot strike.
Some 140,000 travelers will be affected by the grounding, the airline said Tuesday.
"Lufthansa deeply regrets the resulting inconvenience to its customers," it said.
The pilots union, Vereinigung Cockpit, began its strike on long-haul flights Tuesday, forcing the cancellation of 90 flights. On Wednesday it is extending the strike to include medium- and short-haul flights.
Lufthansa has canceled thousands of flights in the past year because of pilots' strikes.
On Tuesday, the airline said services of its subsidiaries Germanwings, SWISS, Austrian Airlines and Brussels Airlines are not affected.
Lufthansa's 5,400 pilots want the airline to keep paying a transition payment for those wanting to retire early, and are opposed to a restructuring of the airline.
Lufthansa says passengers should check its website for details of forthcoming flight cancelations.
Additional reporting by Mashable