Lufthansa pilots will extend today's strike into tomorrow, it emerged last night.
The industrial action is protesting pay and an early retirement scheme.
Today's walkout, the 13th in 18 months, affects 80 out of 170 of the German carrier's long-haul and cargo flights and lasts from 0800 and until 2359 local time (see news, September 7).
Tomorrow's 24-hour strike will hit short-haul Lufthansa and Germanwings flights.
The Vereinigung Cockpit (VC) union is challenging plans to change a retirement policy that sees pilots retire at 55 and retain some of their pay until they reach the state pension age.
VC has offered concessions, including increasing the average retirement age to 60.
However, it wants Lufthansa to stop employing staff on non-German contracts to expand Eurowings, which has an operating licence in Austria. It said this is a precondition for talks.
The frequent strikes by pilots at Lufthansa — and at Air France and Norwegian — are the result of the long-established carriers clashing with unions as they try to cut costs to compete with budget airlines.