Thousands of passengers are facing flight cancellations as airline staff at Lufthansa stage a walkout over retirement rules.
The airline has said about 113,000 people will experience travel delays after 929 flights at Frankfurt, Munich and Düsseldorf airports were due to be cancelled on Monday.
It is the latest in a series of cabin crew strikes, which could last for seven days, after talks with the UFO union broke down.
The union wants to secure pension payments for its 19,000 members if they retire early as part of its contract dispute with Lufthansa, which is trying to cut costs.
Strike action could cost the airline 20 million euros (£14million) per day, according to reports.
An airline spokesman said: “Lufthansa will do its utmost to keep the effects of a strike to a minimum and to inform passengers as soon as possible.
“For that reason, Lufthansa requests all passengers early on to stay up-to-date by checking the flight status on.
“Lufthansa regrets any inconveniences caused by the strike.”