A union representing cabin crew at Lufthansa is expanding a strike campaign, announcing that it will stage all-day walkouts at Frankfurt, Munich and Duesseldorf airports on Monday.

The UFO union called Sunday on all members to walk out from 4.30 a.m. to 11 p.m. (0330 GMT to 2200 GMT) in Frankfurt and Duesseldorf and until midnight (2300 GMT) in Munich.

UFO embarked Friday on walkouts expected to continue for a week, rotating around different airports, though it took a break Sunday. On Saturday, it called out members on the airline’s short- and medium-haul fleet in Frankfurt and crews in Duesseldorf.

The union wants to secure transition payments for its 19,000 members if they retire early as part of its contract dispute with Lufthansa, which is trying to cut costs.

Photo Credit: Passengers queue in front of Lufthansa counters at the airport in Frankfurt, Germany, Saturday Nov. 7, 2015. Boris Roessler / Associated Press