Germanwings was forced to cancel 116 departures – mostly German domestic flights – due to a half-day strike by pilots on Friday.
Around 15,000 passengers were affected, although many were able to travel via the Deutsche Bahn rail network instead.
Germanwings admitted suffering “significant financial loss” as a result of the strike between 6am and noon.
The airline said only a few international passengers turned up at German airports expecting to board flights, which had been cancelled.
Aircraft were leased in from other airlines to allow passengers to return from holiday destinations or travel to them.
“Germanwings deeply regrets any inconvenience caused to passengers as a result of this industrial action,” a spokesman said.
“The airline has striven to keep the effects of the strike action to a minimum.”