Raytheon Aircraft Services has introduced an anti-terrorist security device called Secure Start 1000. The theft deterrent system, which is currently certified on most King Air and Beechjet models, disables the engine start circuits to unauthorised users. Secure Start can be installed during routine maintenance or an inspection, and is operated by a double access code keyboard, so the system remains unlocked during the flight. The keyboard unit indicates to the flight crew if there has been a security breach or tampering before the flight.