Introduction
The automatic flight control system consists of the autopilot flight director system
(AFDS) and the autothrottle system (A/T). The mode control panel (MCP) and
flight management computer (FMC) control the AFDS and the autothrottle system
to perform climb, cruise, descent and approach.
Autopilot Flight Director System
The AFDS consists of three flight control computers (FCCs) and the MCP.
The MCP provides control of the autopilot, flight director, altitude alert, and
autothrottle systems. The MCP selects and activates AFDS modes, and establishes
altitudes, speeds, and climb/descent profiles.
The three FCCs, left, center, and right, control separate hydraulically powered
autopilot control servos to operate flight controls. The autopilot controls ailerons
and elevators. Rudder commands are added only during a multiple autopilot
approach. Nose wheel steering is also added during rollout from an automatic
landing. During an ILS approach with all three autopilots engaged, separate
electrical sources power the three FCCs.
The FCCs also provide inputs for AFDS operating mode displays and flight
director commands on the FMA.