737 Flight Crew Operations Manual
Automatic Flight -
System Description
Boeing Proprietary. Copyright © Boeing. May be subject to export restrictions under EAR. See title page for details.
4.20.6 D6-27370-866-EGP
When engaged, the F/Ds command roll to hold the ground track, and 15
degrees nose up pitch. After reaching a programmed rate of climb, pitch
commands the target airspeed for each flap setting based on maximum
takeoff weight calculations.
• VNAV (armed) - displayed when VNAV is armed prior to takeoff. After
takeoff, VNAV automatically engages at 400 feet RA.
• VNAV (engaged) – VNAV is engaged by pushing the VNAV switch.
With a VNAV mode engaged, the FMC commands AFDS pitch and A/T
modes to fly the vertical profile
• VNAV SPD – the AFDS maintains the FMC speed displayed on the
airspeed indicator and/or the CDU CLIMB or DESCENT pages
• VNAV PTH – the AFDS maintains FMC altitude or descent path with
pitch commands.
• VNAV ALT – when a conflict occurs between the VNAV profile and
the MCP altitude, the airplane levels at the MCP altitude and the
pitch flight mode annunciation becomes VNAV ALT. VNAV ALT
maintains altitude.
• V/S (armed) – V/S mode can be engaged by moving Vertical Speed
thumbwheel
• V/S (engaged) – commands pitch to hold selected vertical speed
• ALT ACQ – transition maneuver entered automatically from a V/S,
LVL CHG, or VNAV climb or descent to selected MCP altitude.
Engages but does not annunciate during VNAV transition
• ALT HOLD – commands pitch to hold MCP selected altitude or
uncorrected barometric altitude at which ALT HOLD switch was
pushed
• MCP SPD – pitch commands maintain IAS/MACH window airspeed or
Mach
• G/S (armed) – the AFDS is armed for G/S capture
• G/S (engaged) – the AFDS follows the ILS glideslope
• FLARE (armed) – during a dual A/P ILS approach, FLARE is displayed
after LOC and G/S capture and below 1500 feet RA. The second A/P
couples with the flight controls and A/P go–around mode arms
• FLARE (engaged) – during a dual A/P ILS approach, flare engages at
50 feet radio altitude. FLARE accomplishes the autoland flare
maneuver.
Roll Modes
• LNAV (armed) – the AFDS is armed (prior to takeoff) to engage LNAV
at 50 feet RA.
• LNAV (armed) – in the approach phase and a missed approach exists in
the flight plan.
September 15, 2016
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