By early 44, Bomber Command ordered that H2S be switched off or used briefly over enemy territory. Naxos was developed by the Germans to home in on H2S. Monica, which was a device that alerted crews that they were being tracked by nightfigthers,also worked against them. This tracker was called Flensburg. Interestingly enough, even until 1942 some Squadrons still believed that by having IFF on over enemy territory it disrupted enemy radar. In fact it acted again as a homing device.