Around 15,000 passengers will be affected today as strike action by pilots grounds 70% of Germanwings flights.
The airline expects to operate less than 50 of its 164 scheduled departures.
The walk-out by members of the pilots’ trade union Cockpit is due to take place between 6am and 12noon local time in Germany.
German domestic flights are the most heavily affected, with passengers offered the option to travel by rail instead.
Flights to holiday destinations will go ahead, with the airline deploying pilots who are normally staffed in the management.
Germanwings will also be leasing aircraft from other airlines to ensure passengers can return from holiday destinations.
Passengers with cancelled flights is can change their departure free of charge on www.germanwings.com or by contacting the call centre.
“Routes served by Eurowings are not affected by the strike, as their pilots are not employed under the Lufthansa group wage tariff agreement,” the airline said.
“Germanwings apologises for any inconvenience caused to passengers by this industrial action, and is striving to keep its effects to a minimum.”