Strikes by security staff at Berlin's two airports on Monday caused around 75 flights to be delayed or cancelled.
Around 400 security personnel stopped working for about four hours at Schoenefeld and Tegel airports early on Monday due to an ongoing wage dispute.
Airlines including Lufthansa, Easyjet, Ryanair and Aeroflot canceled flights ahead of the walkout. Several flights were significantly delayed.
Just less than 50 flights were struck off altogether, while around 25 were delayed, according to Berlin's airport management company FBB.
The organizing union, Verdi, said the strikes were meant as a warning to ensure that the employers' association makes a reasonable offer before the next round of labor negotiations starts on January 23. Ver.di has said employers "provoked" the strike by offering a pay increase of 2 percent over two years.
"We hope that the signal has been understood on the employers' side," a spokesman told dpa.
Some 3,000 people are employed by private security companies at the two airports, according to Verdi. The union is calling for aviation security personnel across the country to be paid 20 euros (23 dollars) an hour.
Employer association BDLS says this could amount to a 30 percent increase in some cases.