The F-89 was a twin-engine, all-weather fighter-interceptor designed to locate, intercept, and destroy enemy aircraft by day or night under all types of weather conditions. It carried a pilot in the forward cockpit and a radar operator in the rear who guided the pilot into the proper attack position. The first F-89 made its initial flight in August 1948 and deliveries to the Air Force began in July 1950. Northrop produced 1,050 F-89s.  On July 19, 1957, a Genie test rocket was fired from an F-89J, the first time in history that an air-to-air rocket with a nuclear warhead was launched and detonated. Three hundred and fifty F-89Ds were converted to "J" models which became the Air Defense Command's first fighter-interceptor to carry nuclear armament.