The Northrop P-61 Black Widow was the first operational U.S. military aircraft designed specifically for night interception of aircraft, and was the first aircraft specifically designed to use radar. It was an all-metal, twin-engine, twin-boom design developed during World War II. The first test flight was made on 26 May 1942, with the first production aircraft rolling off the assembly line in October 1943. The last aircraft was retired from government service in 1954.
Although not produced in the large numbers of its contemporaries, the Black Widow effectively operated as a night-fighter by United States Army Air Forces squadrons in the European Theater, the Pacific Theater, the CBI Theater and the Mediterranean Theater during World War II. It replaced earlier British-designed night-fighter aircraft that had been updated to incorporate radar when it became available. After the war, the F-61 served in the United States Air Force as a long-range, all weather, day/night interceptor for Air Defense Command until 1948, and Far East Air Force until 1950.
The first unit to receive production aircraft was the 348th Night Fighter Squadron in Florida which was responsible for training night fighter crews.
P-61 crews trained in a variety of ways. Several existing night fighter squadrons operating in the Mediterranean and Pacific theatres were to transition directly into the P-61 from Bristol Beaufighters and Douglas P-70s, though most P-61 crews were to be made up of new recruits operating in newly commissioned squadrons. After receiving flight, gunnery or radar training in bases around the U.S., the crews were finally assembled and received their P-61 operational training in Florida for transfer to the European Theatre, or California for operations in the Pacific Theatre.