At the start of the Second World War in 1939, Bomber Command faced four problems. The first was lack of size; Bomber Command was not large enough effectively to operate as an independent strategic force. The second was rules of engagement; at the start of the war, the targets allocated to Bomber Command were not wide enough in scope. The third problem was the Command's lack of technology; specifically radio or radar derived navigational aids to allow accurate target location at night or through cloud. (In 1938, E. G. "Taffy" Bowen proposed using ASV radar for navigation, only to have Bomber Command disclaim need for it, saying the sextant was sufficient. ) The fourth problem was the limited accuracy of bombing, especially from high level, even when the target could be seen by the bomb aimer.