737 MAX Flight Crew Operations Manual
Automatic Flight
Chapter 4
System Description
Section 20
MN-FLT-OH-201
4.20.1
20 System Description
System Description
File Highlight
General
The automatic flight system (AFS) consists of the autopilot flight director system
(AFDS) and the autothrottle (A/T). The flight management computer (FMC)
provides N1 limits and target N1 for the A/T and command airspeeds for the A/T
and AFDS.
The AFDS and A/T are controlled using the AFDS mode control panel (MCP) and
the FMC. Normally, the AFDS and A/T are controlled automatically by the FMC
to fly an optimized lateral and vertical flight path through climb, cruise and
descent.
AFS mode status is displayed on the flight mode annunciation on each pilot’s
primary display.
Autopilot Flight Director System (AFDS)
The AFDS is a dual system consisting of two individual flight control computers
(FCCs) and a single mode control panel.
The two FCCs are identified as A and B. For A/P operation, they send control
commands to their respective pitch and roll hydraulic servos, which operate the
flight controls through two separate hydraulic systems.
For F/D operation, each FCC positions the F/D command bars on the respective
attitude indicator.
MCP Mode Selector Switches
The mode selector switches are pushed to select desired command modes for the
AFDS and A/T. The switch illuminates to indicate mode selection and that the
mode can be deselected by pushing the switch again. While a mode is active,
deselection can be automatically inhibited and is indicated by the switch being
extinguished.
When engagement of a mode would conflict with current AFS operation, pushing
the mode selector switch has no effect. All AFDS modes can be disengaged either
by selecting another command mode or by disengaging the A/P and turning the
F/Ds off.
March 1, 2021
