 The system given the official title of FuMB 1 (for , Radio measuring device).From July 1940, the British fitted the RAF Mk II AI (Airborne Interception) radar into Coastal Command aircraft for use as the Mk II "1½-metre ASV".The radar's known AI weaknesses — problems due to land clutter and inability to determine height, which caused its failure in night fighters — were no handicap in this new role.