A labor union in Germany has called on ground staff for Lufthansa to walk off the job at seven airports on Tuesday following a similar strike earlier this month.

The Ver.di union said Sunday that the one-day strike will affect the airports in Frankfurt and Munich, Lufthansa’s two main hubs, as well as Berlin, Duesseldorf, Hamburg, Cologne-Bonn and Stuttgart. It will run from 4 a.m. Tuesday to 7:10 a.m. Wednesday.

A 27-hour strike at five of the same airports that started Feb. 7 prompted the airline to cancel hundreds of flights.

The union is seeking pay raises of 12.5%, or at least 500 euros ($539) more per month, in negotiations for about 25,000 employees, including check-in, aircraft handling, maintenance and freight staff. Several-hour or one-day “warning strikes” are a common tactic in German contract negotiations.

A round of talks on Feb. 12 produced no agreement. More negotiations are scheduled for Wednesday.