At the same time, the carrier said yesterday it had filed a court injunction in a bid to prevent the industrial action -- the 13th walkout in 18 months -- as the company struggles to end a long-running dispute over early retirement provisions.
"One thousand Lufthansa flights are cancelled, 140,000 passengers will be affected," Lufthansa said in a statement after the pilots' union, Vereinigung Cockpit (VC), announced that it was extending a strike that began today into a second day tomorrow.
Only Lufthansa services would be hit, while flights by the group's other airlines, Germanwings, Swiss, Austrian Airlines and Brussels Airlines would operate normally.
The carrier said it apologised to passengers for any inconvenience caused and added they would be able to rebook their flights free of charge.
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Passengers on domestic, inner-Germany flights would be able to swap their tickets for a ticket on the German national railway, Deutsche Bahn.
The first day of the walkout on Tuesday had affected only long-haul flights, and but there would also be knock-on effects again on Wednesday, meaning that 52 of the scheduled 176 long-haul flights would be grounded, Lufthansa said.
At the same time, management upped the ante, announcing it would seek damages of 60 million euros (USD 67 million) from Cockpit for the loss of earnings a first strike had caused back in April 2014, when the wage agreement with pilots at the time was still in force.