An Airline Gets with In-Line Monitoring
F. S. Bonney · IEEE Transactions on Aerospace and Electronic Systems · 1966
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.