Scandinavian Airlines canceled dozens of flights to and from Copenhagen on Thursday as Danish cabin crew remained on strike for a third day.
The strike has affected more than 20,000 passengers and cost the airline an estimated 20 million kroner (2.7 million euros; $3.7 million).
SAS called the strike illegal and said the Danish Cabin Attendants Union could face legal action if the crews do not return to work.
The flights attendants walked off their jobs Tuesday afternoon because of a dispute over working conditions.
Scandinavian Airlines is the joint flag carrier of Sweden, Denmark and Norway. Flights operated by Norwegian or Swedish cabin crew were not affected by the strike.