Frankfurt - Lufthansa pilots Tuesday walked off the job for the fifth time this year over retirement benefits.
Lufthansa pilots' union, Vereinigung Cockpit, said the industrial action would take place at Frankfurt airport, Germany's largest, from 06:00 to 21:00 GMT.
Travellers were expected to face fresh disruptions as long-haul flights would be affected. The union said services on Airbus A380, A330, A340 and Boeing B747 would be hit.
The airline has instituted a special flight plan to enable more than half of its planned intercontinental flights to take place.
"We are confident that we can fulfil out special flight plan," said a Lufthansa spokesman.
The situation at Frankfurt International Airline, Lufthansa's main German hub, was calm, said Markus Wahl, speaking for the Vereinigung Cockpit.
It said it was forced to resort to such measures as talks with the Lufthansa management were deadlocked and it had not been offered a compromise.
Tuesday's strike action comes just as pilots at Air France ended a two-week strike over that airline's cost-cutting plans. That strike cost Air France more than $254m, according to management.