Hundreds of German passengers were facing travel upheaval on Monday with security staff at Berlin's two airports set to walk out in a pay dispute.
The action, called by the powerful Verdi union at the German capital's Tegel and Schoenefeld airports, is due to start at 05:00 am (0400 GMT) and end at 8:45 am.
Some 80 flights are expected to be affected, according to DPA news agency, mostly at the city's main Tegel airport.
German flagship carrier Lufthansa said it was cancelling four flights on its Berlin-Frankfurt route and four more between Berlin and Munich.
The roughly 850 passengers booked on those flights could use their tickets to travel by train instead, Lufthansa added.
"We regret that our passengers have to start the new year with disruptions," Lufthansa board member Detlef Kayser told DPA.
The strike comes after Verdi, which represents some 23,000 airport security workers nationwide, said talks with the BDLS employers' association were deadlocked.
The union wants to see wages raised to 20 euros ($23) per hour for workers carrying out passenger, freight, personnel and goods checks at German airports.
Rates vary across the country but staff working in passenger security at Tegel and Schoenefeld currently earn an hourly rate of 17.12 euros.
The employers' association has offered wage increases of between 2.0 and 8.1 percent annually.
The next round of talks is scheduled for January 23.
Explore further: Lufthansa cancels 800 flights Tuesday in German airport strikes