ADVERTISEMENTFlights to and from Germany are grounded until tomorrow (Wednesday), with 200,000 passengers likely to be affected.
80-90% of Lufthansa flights are cancelled due to the ground staff strike.
The walkout began at Frankfurt airport last night. It continued at Munich, Berlin, Duesseldorf, Hamburg, Cologne-Bonn and Stuttgart airports this morning.
Services are expected to resume at 7.10am tomorrow (Wednesday), though disruption is likely to continue for some time after this.
Lufthansa has advised passengers not to travel to the airport unless you know your flight is still scheduled to depart.
It is the second time this month that a strike has caused mass flight cancellations for Lufthansa.
How to find out if your flight is cancelled
In a statement, Lufthansa say: "Passengers who are affected by flight cancellations as a result of the Verdi strike will be informed by email or via the Lufthansa app.
We regret the inconvenience this strike might cause you."
There is further information on delays and cancellations on Lufthansa's website.
You can also keep eye on Lufthansa's X account for further updates.
Beware: Lufthansa customer service has warned customers that there is a fake WhatsApp number being circulated. The airline does not have a WhatsApp account to communicate with customers.
Lufthansa strike: Can you get a refund?
Lufthansa have said: "Flights that have been canceled due to the strike can be rebooked free of charge at http://lufthansa.com, in the Lufthansa app or via the service centers."
They also say: "Due to the strike, the rebooking desks are unfortunately not staffed."
If your flight is domestic, you can get a voucher for an equivalent train journey via the Lufthansa website.
Under EU rules, you are entitled to a full refund if your flight is cancelled.
Passengers compain about Lufthansa customer service
Travellers have taken to X, formerly Twitter, to complain that it has been very difficult to speak to someone at Lufthansa to get information or rebook flights.
At Frankfurt airport, where the walkouts will kick off tonight, a social media user filmed a long queue of travellers waiting to speak to customer service.
Why is the Lufthansa strike happening?
The Ver.di union announced the warning strike on Sunday.
ADVERTISEMENTWarning strikes are a tactic used by unions to warn that longer strikes could follow if demands are not met.
The union is seeking pay raises of 12.5%, or at least €500 more per month, in negotiations for about 25,000 employees, including check-in, aircraft handling, maintenance and freight staff.
A round of talks on 12 February produced no agreement. More negotiations are scheduled for Wednesday.