Hurricanes from 151 Squadron (also from North Weald), and Supermarine Spitfires from 54, 65 and 74 Squadrons based at Hornchurch Airfield scrambled. None of the Royal Air Force pilots had been in action and few had seen a German aircraft. Communication between the pilots and ground control was poor and there was no procedure for pilots to distinguish between British and "Luftwaffe" aircraft. Identification friend or foe (IFF) sets were still being developed and had not been installed in many RAF aircraft.