After a Junkers Ju 88 night fighter landed in Scotland in 1944, they were able to reverse engineer the Erstling and introduced the Perfectos system to trigger it. The signals were superimposed on existing radar displays, allowing the Perfectos operator to measure both the direction and range to the Erstling-equipped aircraft. When night fighter losses suddenly spiked, German pilots were told to turn their Erstling units off, leading to friendly fire incidents.