At the urging of R.V. Jones, the RAF changed their raid tactics to gather all of their bombers into a single "stream". This meant that the ground-based portion of the system was overwhelmed; with only one or two searchlights or radars available per "cell", the system was able to handle perhaps six interceptions per hour. By flying all of the bombers over a cell in a short period, the vast majority of the bombers flew right over them without ever having been plotted, let alone attacked. German success against the RAF plummeted, reaching a nadir on 30/31 May 1942, when the first 1,000-bomber raid attacked Cologne, losing only four aircraft to German night fighters.