Monica (radar)
Monica was a range-only tail warning radar for bombers, introduced by the RAF in the spring of 1942. It operated at frequencies of around 300 MHz. It was developed at the Bomber Support Development Unit in Worcestershire.
Unfortunately for the RAF, the Germans quickly developed a passive radar receiver, Flensburg (FuG 227), which was used by Luftwaffe nightfighters from Spring 1944 onward to home in on bombers using Monica. However, Monica-equipped aircraft did not suffer an increased casualty rate overall.[citation needed] On the morning of 13 July 1944, a Junkers Ju 88G-1 nightfighter equipped with Flensburg mistakenly landed at RAF Woodbridge. After examining the Flensburg equipment, the RAF ordered Monica withdrawn from all Bomber Command aircraft.
The U.S. Army Air Corps also used Monica as the AN/APS-13.