After the chaos at Lufthansa on Wednesday, air passengers in Germany will face further turbulent days. The airline is expecting a largely normal process again for Thursday after the serious IT failure. A spokeswoman for the airline said in the morning that there were no known flight cancellations or delays.

But as early as Friday, the Verdi union wants to paralyze seven airports in Germany with a warning strike – with consequences for hundreds of thousands of passengers, as the airport association ADV fears. He expects that large parts of domestic and international air traffic will not take place. The airports in Frankfurt, Munich, Stuttgart and Hamburg announced that they would cease regular passenger operations after the strike was announced on Friday.

The ADV warned of “massive obstructions in air traffic”. The warning strike will lead to a good 2,340 flight cancellations in domestic and international air traffic, the association said. “More than 295,000 passengers become the plaything of the Verdi strike tactics,” criticized the ADV and spoke of an “unprecedented escalation”.

Regular passenger operations will not be possible at Germany’s largest airport, Frankfurt, on Friday due to the warning strike, the operating company Fraport said. Emergency flights are excluded. In Frankfurt alone, 1005 flight movements were planned for Friday. The operating company spoke of 137,000 affected passengers. She called on passengers not to come to the airport in the first place and to get information from their airline. “Passengers who want to start their journey in Frankfurt cannot catch their flight.” Transfer traffic is also affected.

Lufthansa has to cancel around 1,200 flights in Frankfurt and Munich alone on Friday, as a spokesman said. The number as of Wednesday evening will increase.

Verdi had announced that it would paralyze the airports in Munich, Frankfurt, Hamburg, Stuttgart, Dortmund, Hanover and Bremen for the whole day on Friday. The warning strike is scheduled to begin early Friday morning and end on Saturday night. Aid deliveries to the earthquake victims in Turkey and Syria should be excluded.

With the warning strike, the employees want to emphasize their demands in the collective bargaining dispute between the federal and local governments. In addition to the public service, there are local negotiations for ground handling services and a nationwide round of collective bargaining for aviation security.

The warning strike takes place at the start of the Munich Security Conference, which is considered the world’s most important meeting of politicians and experts on security policy and lasts from Friday to Sunday. Munich Airport emphasized that flights for the Munich Security Conference are exempt from the suspension of regular passenger operations in Munich. The security conference is working on being able to guarantee the arrival of the participants, it said on Wednesday.

Verdi and the civil servants’ association dbb are demanding 10.5 percent more income in the collective bargaining dispute, but at least 500 euros more for the approximately 2.5 million federal and local employees. The term should be twelve months. The employers have rejected the claims. The second round of negotiations is scheduled for February 22nd and 23rd in Potsdam.

Already on Wednesday there were delays and cancellations for tens of thousands of passengers with connections via the Frankfurt hub. A cable damage on a Frankfurt S-Bahn line had led to a failure of the computer systems at Lufthansa.