Aeronautica Militare, Napoli, 1955. The T-6 Texan was a single-engine advanced trainer aircraft designed by North American Aviation, used to train fighter pilots of the United States Army Air Forces, United States Navy, Royal Air Force and other air forces of the British Commonwealth during World War II. The T-6 is known by a variety of designations depending on the model and operating air force. The USAAC called it the "AT-6", the US Navy, the "SNJ", and British Commonwealth air forces, the Harvard. It remains a popular warbird aircraft.