BRIXMIS exercised the British legal right under the Potsdam Agreement to use the airspace over both West and East Berlin, as well as the air corridors to and from West Germany to the city. Two De Havilland Chipmunk T10s were based at RAF Gatow and RAF aircrew posted to BRIXMIS had access to them for the conduct of photographic reconnaissance flights within the designated airspace; a radius of 12 nautical miles within the Berlin Control Zone (BCZ) from the Berlin Air Safety Centre (BASC) in West Berlin.