Hundreds of flights were canceled across Germany on Monday after a key labor union called for security and services staff to walk off the job in a dispute over pay.

About 160 of a planned 290 takeoffs and landings were called off at Dusseldorf Airport. Berlin’s Brandenburg airport also registered dozens of cancellations and delays.

Passengers traveling from Deutsche Lufthansa AG’s Frankfurt hub should also expect major disruptions and flight cancellations on Tuesday. Airport operator Fraport AG “strongly” advised all originating passengers not to show up as security checkpoints outside the transit area will remain closed throughout March 15, which means travelers won’t be able to pass through the legally required security checks and get to their flights, Fraport said in a tweet on Monday.

While transfer processes for connecting passengers in the transit area will still largely be possible, transfer passengers should also expect disruptions and delays due to the strike, it said.

The Vereinte Dienstleistungsgewerkschaft union urged security and passenger control staff to join warning strikes at numerous German airports after three rounds of negotiations ended without agreement.

Collective bargaining for 25,000 security staff at commercial airports between Verdi and BDLS, the association of aviation security companies, will continue on March 16 and 17 in Berlin, Verdi said.