777 Autopilot Flight Director System

This paper overviews the design architecture and operation of the 777 Autopilot Flight Director System (AFDS). The AFDS provides the functions necessary for automatic control and/or flight director guidance of the 777 airplane selected flight path. The system consists of a Mode Control Panel (MCP), which provides the primary interface between the flight crew and the AFDS; three Autopilot Flight Director Computers (AFDCs), which provide triplex computations for the flight director (F/D), autopilot (A/P), maintenance, and backdrive functions; and six backdrive control actuators (BCA), which provide visual and tactile feedback indications to the flight crew through dual redundant control of wheel, column, and pedal positions commanded by the autopilot function.<>