Germany's Berlin-Brandenburg airport canceled around 300 flights on Monday as security staff began a full-day walkout over an ongoing dispute over pay and work conditions.
The strike began at 3.30 a.m. local time (0130GMT) and is set to continue until midnight (2200 GMT), according to the ver.di trade union.
"Due to the announced warning strike at the aviation security controls, no departures are possible today," the airport operator said in a statement.
"Arriving flights may also be affected by cancellations and changes to the flight schedule may occur due to the warning strike," it added.
Passengers were advised to contact their airline or travel agent for information on rebooking and alternative travel options.
The union, which staged several strikes last week at other major airports, is demanding an increase in overtime pay, and surcharges for work on weekends, public holidays, and during night shifts.
The latest round of negotiations between the union and the Federal Association of Aviation Security Companies (BDLS) failed to make any significant progress earlier this month.
A new round of negotiations is expected to take place on April 27 and 28.
