An Airline Gets with In-Line Monitoring

Today´s operation demands faster and more accurate methods of detecting in-flight failures of navigational instruments. New, automatic self-monitor techniques developed and installed for attitude and heading reference systems are described in this paper. Logic signals generated by these so-called ??In-Line?? monitor functions trigger a conspicuous warning flag in each related primary display. A new sensing and logic control unit dubbed the ??SMART BOX?? is installed as a central monitor station for all systems furnishing control signals to the Flight Director and Autopilot. It responds to in-line monitor signals to disengage the autopilot, and retract the flight director display from view in the event of a system malfunction.