DFS Deutsche Flugsicherung GmbH, the German air navigation service provider, is a State-owned company under private law with 5,600 employees. Around 2,200 air traffic controllers guide more than three million flights through German airspace in peak years, up to 10,000 every day. The company operates control centres in Bremen, Karlsruhe, Langen and Munich as well as control towers at the 15 designated international airports in Germany. The subsidiary DFS Aviation Services GmbH markets and sells products and services related to air navigation services, and provides air traffic control at nine regional airports in Germany and at London Gatwick Airport and Edinburgh Airport in the UK. DFS is working on the integration of drones into air traffic and has set up a joint venture, Droniq GmbH, with Deutsche Telekom. Other subsidiaries include R. Eisenschmidt GmbH, Kaufbeuren ATM Training GmbH (KAT), and the joint venture FCS Flight Calibration Services GmbH.