AA Command's experience had shown that the power-operated, remotely controlled static Mk IIC 3.7-inch HAA gun, which had power traverse and automatic fuze-setting, accompanied by the most sophisticated Radar No 3 Mark V (the SCR-584 radar set) and No 10 Predictor (the all-electric Bell Labs AAA Computer), were required to deal effectively with V-1s, but 21st Army Group's mobile HAA units did not have experience with this equipment.