 Complete the following phrase:  Almost continuous attacks went on through early 1942, particularly aimed at airfields, shipping and port installations. Heavy raids were made by the Luftwaffe in daylight while smaller harassing raids were made by the Regia Aeronautica. By this stage of the siege, night bombers could be engaged by the HAA guns using visual height control at targets illuminated by SL or by the GL Mark II gun-laying radar, or with predicted barrage fire. The SL layout was at spacing and with the clear air of Malta 23 per cent of raids were illuminated at heights of up to . The lights were controlled by a searchlight controller in the RAF Fighter Operations Room. Until December 1941, when Junkers Ju 88s began night operations, RAF Hawker Hurricanes were able to destroy 40 per cent of Italian-manned aircraft that had been illuminated. By June, the size of night raids had grown to 90 aircraft, while day raids were as few as eight aircraft. These raids were targeted at RAF airfields, but the raiders lost heavily and the scale of attacks dwindled in July. In the first week in August only seven bombers approached the island, the lowest number for everal months. However, the vital supply convoys came under heavy attack and suffered serious losses of ships and cargoes. However, the survivors of the 