As early as 1936, it was realized that the "Luftwaffe" would turn to night bombing if the day campaign did not go well and Watson-Watt had put another of the staff from the Radio Research Station, Edward Bowen, in charge of developing a radar that could be carried by a fighter. Night-time visual detection of a bomber was good to about 300 m and the existing Chain Home systems simply did not have the accuracy needed to get the fighters that close. Bowen decided that an airborne radar should not exceed 90 kg (200 lb) in weight or 8 ft³ (230 L) in volume, and should require no more than 500 watts of power. To reduce the drag of the antennae, the operating wavelength could not be much greater than one metre, difficult for the day's electronics. However, Airborne Interception (AI), was perfected by 1940 and was instrumental in eventually ending the Blitz of 1941. Watson-Watt justified his choice of a non-optimal frequency for his radar, with his oft-quoted cult of the imperfect, which he stated as "Give them the third-best to go on with; the second-best comes too late, the best never comes".