*
With the G/S mode active, G/S changes to arm and glideslope must capture again. The active pitch mode is V/ S or FPA until G/S is captured.

The autopilot will engage in the takeoff mode when all these conditions are true:
*
The airplane is on the ground

*
A flight director is on

*
The mode selected is TO/GA.

Engage Autopilot With Flight Director Off
The active pitch mode is vertical speed or flight path angle.
If the airplane is in a bank of five degrees or less, the autopilot commands wings level. When the airplane bank is at three degrees or less, the airplane holds the heading or track that is present. The active roll mode is heading or track hold.
The PFDs show the applicable pitch and roll modes and A/P status. The applicable mode select switch LED on the MCP is also on.
Autopilot Engage Inhibit
The AFDCs have an inhibit that prevents the engagement of the autopilot during the takeoff roll and immediately after it. You cannot engage the autopilot when all these conditions are true:
*
The ground speed is more than 80 knots

*
The radio altitude is less 50 feet.

This engage inhibit function does not operate if the airplane takes off with the autopilot already engaged.
Training Information Point
The airplane is not certified for takeoff with the autopilot engaged.
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777 AIRCRAFT MAINTENANCE MANUAL

AFDS -OPERATION -AUTOPILOT ENGAGE

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AFDS -ROLL ATTITUDE HOLD

General
In this mode, the airplane holds a roll attitude until the pilot selects another roll mode.
Bank Angle More Than Five Degrees
If the pilot engages the autopilot when the bank angle is more than five degrees and the flight director is off, the airplane holds the roll attitude present at that time.
ATT stays as the active roll mode until the pilot selects another roll mode. The PFD shows ATT (roll attitude) for the active roll mode.
Bank Angle Five Degrees or Less
If the pilot engages the autopilot when the bank angle is five degrees or less and the flight director is off, the airplane will roll to wings level. The active roll mode is heading hold or track hold.
The PFD shows HDG HOLD or TRK HOLD as the active roll mode.
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777 AIRCRAFT MAINTENANCE MANUAL

AFDS -ROLL ATTITUDE HOLD

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AFDS -OPERATION -ROLL INTRODUCTION

General
These AFDS roll modes are available during climb, cruise and descent:
*
Lateral navigation (LNAV)

*
Heading hold (HDG HOLD)

*
Track hold (TRK HOLD)

*
Heading select (HDG SEL)

*
Track select (TRK SEL).

LNAV
The commands come from the active FMCF when there is a valid navigation data base and an active flight plan. The CDUs can send LNAV steering commands when there is no active FMCF. The AFDS use this priority to select a CDU command:
*
Left, if valid

*
Center, if left not valid

*
Right, if left and center are not valid.

Heading/Track Hold
In this mode, the airplane holds either heading (HDG) or track (TRK).
If the HDG/TRK display on the MCP shows TRK, the airplane holds track.
If the HDG/TRK display on the MCP shows HDG, the airplane holds heading.
Heading/Track Select
In this mode, the airplane turns to the heading or track that shows in the heading/track window.
If the HDG/TRK display shows HDG, the airplane goes to and holds the heading that shows in the heading/track window.
If the HDG/TRK display shows TRK, the airplane goes to and holds the track that shows in the heading/track window.
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777 AIRCRAFT MAINTENANCE MANUAL

AFDS -OPERATION -ROLL INTRODUCTION

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AFDS -OPERATION -LNAV

General
LNAV has these two sub-modes:
*
LNAV arm

*
LNAV active.

LNAV Arm
Push the LNAV switch on the MCP to arm LNAV. To remove the LNAV arm status, push the LNAV switch again before LNAV captures or select another roll mode.
　
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