S9 is a line on the Berlin S-Bahn. It operates from Schönefeld Flughafen to Pankow over:
Future extension
A southern extension from Schönefeld station, serving the new Berlin Brandenburg International airport, is expected to open in 2018 or 2019. It will include two new stops: Waßmannsdorf and Berlin Brandenburg Airport (terminal).
References
S9 (Berlin) Wikipedia(Text) CC BY-SA