At the country's largest airport in Frankfurt, 450 of 1,117 departures were scrapped, with 275 of 920 flights leaving from Munich also grounded.

Around 4,800 pilots at Lufthansa and its cargo subsidiary Lufthansa Cargo are striking in a dispute over higher company pensions.

Meanwhile, cabin crew are staging a warning strike to force negotiations on several collective bargaining issues.

The UFO union has also called on staff at regional subsidiary Lufthansa CityLine, which is facing closure, to join the walkout.

Management has rejected the unions' demands.

"The strike is going as we expected," said UFO expert Harry Jaeger on Thursday at Frankfurt airport, where long queues formed at Lufthansa counters.

Passengers were advised not to travel to the airport without checking their flight status.

The Cockpit Association pilots' union also said it has seen "very good participation in Frankfurt."

"What we need is a new offer," said the union's president, Andreas Pinheiro. "Lufthansa has not been in touch."

He warned that further strikes could take place in future.

"As a trade union, we do not have many means at our disposal other than industrial action," Pinheiro explained. "If there is no offer, the spiral of escalation continues."

(In arrangement with DPA)