Cabin crew at SunExpress Deutschland, Lufthansa CityLine, Germanwings and Eurowings are taking part in the strike action, which was originally set to end at 11am local time, the union said in a statement on Sunday. The walkouts apply to all departures from German airports during the targeted period.

A Lufthansa spokeswoman said on Saturday that the airline aimed to operate all its flights through the day, despite the union’s action, and no one was available for comment on Sunday morning. A separate strike planned for the main carrier was cancelled on Friday after the company agreed to a 2% wage increase by the end of the year, UFO said.

The labour dispute adds to headaches at the German airline, which warned in July that the fight for market share means business performance could deteriorate further in the second half. Its domestic market has become a key battleground, with competition intensifying just as headwinds from the German economic slowdown combined with simmering trade tensions.