Deutsche Verkehrsfliegerschule
The Deutsche Verkehrsfliegerschule (DVS), German Air Transport School, was a covert military-training organization operating as a flying school in Germany. It began during the Weimar Republic in Staaken, Berlin in 1925 and its head office was transferred in 1929 to Broitzem airfield near Braunschweig.
Source: Wikipedia — Deutsche Verkehrsfliegerschule (CC BY-SA 4.0)