the raytheon sentinel is an airborne battlefield and ground surveillance aircraft operated by the royal air force. based on the bombardier global express ultra long range business jet, it was adapted by raytheon to meet the raf's requirements. originally known as the astor (airborne stand-off radar) programme the aircraft is operated by a raf squadron manned by both air force and army personnel. the sentinel is interoperable with other allied systems such as jstars and the nato alliance ground surveillance (ags) system.