Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The British Aerospace BAe 125 is a twin-engined mid-size corporate jet, with newer variants now marketed as the Hawker 800. It was known as the Hawker Siddeley HS.125 until 1977. It is also used by the British Royal Air Force as a navigation trainer, and was used by the United States Air Force as a calibration aircraft.