The Grünau Cross–Berlin Brandenburg Airport railway is a railway line in the south of Berlin, the capital of Germany, and in the adjacent areas of Brandenburg. It is used by the Berlin S-Bahn. The first, 5.9-kilometre-long (3.7 mi) section was opened in 1962 and served mainly as a connection to Berlin Schönefeld Airport and the associated long-distance station. In 2011, a 7.7-kilometre-long (4.8 mi) extension went into operation to connect with Berlin Brandenburg Airport (BER). Due to delays in the commissioning of BER Airport, this section has only been used for public transport since October 2020.

Schönefeld station is a railway station in Schönefeld next to the former Berlin Schönefeld Airport, just outside Berlin. The station is on the Grünauer Kreuz–Berlin Brandenburg Airport railway and is served by S-Bahn lines S9 and S45. It is also served by RB 24 and RB 32.