The German airline Lufthansa lost a last-minute legal attempt to stops cabin crew from striking.
The airline has been forced to cancel around 1,300 flights as the two-day walkout started at midnight over pay and conditions.
Some 180,000 passengers will face travel disruption as Lufthansa has cancelled 700 flights on Thursday and 600 for Friday.
The airline said they regret the inconvenience to their passenger, “We will do everything we can to minimise the impact of this massive strike on our customers.”
Daniel Flohr the unions vice president warned that further strikes could come at “any time.”
Eurowings, Swiss, Brussels Airlines and Austrian Airlines who are Lufthansa’s other airlines that cover their flights are not affected.