AIR FRANCE-KLM 
Lufthansa earlier canceled 750 flights, or about half the flights it planned to operate on Wednesday under its namesake brand, due to the strike on short and medium-haul flights planned by pilots for Wednesday.
But just two hours before the start of that strike, pilots' union Vereinigung Cockpit said it was calling for further action for 24 hours on Thursday, this time on Lufthansa long-haul flights, which are among its most profitable, and at its cargo arm.
The German airline is trying to cut costs and renegotiate expensive labor agreements as it tries to compete with low-cost carriers and rivals such as Emirates and Turkish Airlines, but its efforts have been resisted by pilots who staged 10 strikes last year.
Chief Executive Carsten Spohr has vowed to stay firm in the row with pilots and the carrier has said that growth at its main brands is dependent on cost cuts. Rival Air France-KLM has scaled back budget expansion plans after a strike by its pilots last year.
Strikes by pilots and security staff cost Lufthansa 232 million euros ($246 million) in 2014. Last week, it forecast an increase in core earnings this year but said the forecast did not include the cost of any further strikes.
The pilots want to maintain retirement benefits for new starters that allow them to retire at 55 and receive up to 60 percent of their pay ahead of the state pension age of 65.
Lufthansa has said it will leave that agreement in place for those starting at the company before 2014 but wants to increase the average age of retirement to 61 years of age. It says the current average age of retirement for its pilots is 59.5 years.
The pilots have also called for mediation to resolve other outstanding issues, including how to reduce costs on long-haul flights to tourist destinations and regular pay talks, but Lufthansa has said it wants mediation only on the issue of early retirement benefits.
Late on Tuesday, the union said Lufthansa should either negotiate seriously or agree to mediation covering all outstanding issues.
Wednesday's strike will affect 80,000 passengers.
Flights at Lufthansa brands Germanwings, Eurowings, Air Dolomiti, Swiss and Austrian will be unaffected by Wednesday and Thursday's planned strikes.
(Additional reporting by Edward Taylor in Frankfurt and Jeffrey Dastin in Washington; Editing by Jane Merriman, David Holmes and Susan Thomas)
By Maria Sheahan and Victoria Bryan
