Peacetime practice involved the dropping of small practice bombs on instrumented bombing ranges, and a system of predicted bombing using radio tones to mark the position of the bomb drop over non-range targets, the bomb error being calculated by a ground radar unit and passed either to the crew during flight or to a headquarters for analysis. Use of the Valiant's Navigational and Bombing System (NBS) and the high quality of assigned crews, who were typically veterans and often had been previously decorated for wartime service, meant a high level of bombing accuracy could be achieved, greater than that of aircraft during the Second World War. According to Gunston and Gilchrist, Valiant crews were able to place practice bombs from an altitude of within a few meters of their assigned target.