Germanwings, a subsidiary of Germany's biggest airline Lufthansa, said up to 15,000 passengers were affected by today's strike which started at 6 am (local time) and was to last until noon.
More than a hundred flights, mostly domestic connections from airports in Cologne, Stuttgart, Duesseldorf, Dortmund, Hannover, Hamburg and Berlin, were grounded by the strike.
The airline said on its website it was trying to rebook customers free of charge.