737 Flight Crew Operations Manual
Flight Management, Navigation Chapter 11
FMC Descent and Approach Section 43
Boeing Proprietary. Copyright © Boeing. May be subject to export restrictions under EAR. See title page for details.
D6-27370-866-EGP 11.43.1
43 FMC Descent and ApproachFMC Descent and ApproachFile Hig hlight
Introduction
The descent phase begins at the top of descent point and continues to the end of
descent point. Planning for the descent phase begins during cruise.
The approach phase begins at the end of descent point and continues to touchdown
or go–around. When a go–around is accomplished, the FMC enters the cruise
phase.
The only automatic page change provided in the descent/approach modes is the
transition from cruise to descent at the top of descent.
Early Descent
Early descent may be commenced prior to reaching the top of descent by using the
DES NOW prompt.
YW273, YW274
(SB Changes YK981 - YQ456)
A CRZ DES occurs upon lowering the MCP ALT to a lower altitude while at or
above any descent constraint altitude and pressing ALT INTV. The airplane must
be further than 50 nm from the Top of Descent (T/D) at the current cruise altitude.
If within 50 nm of the top of descent, the Early Descent mode will be invoked. In
the previous Operational Flight Programs (OFPs), this action resulted in always
going into the Early Descent mode of operation regardless of distance from the top
of descent.
• A cruise descent can be started by using the altitude intervention feature
on the MCP when the airplane is not within a distance of 50 NM to the
T/D.
• Altitude Intervention may be used to initiate Early Descent when the
airplane is 50 nm or less to T/D.
• If Altitude Intervention is used to initiate descent when 50 NM or less to
T/D with VNAV engaged and the MCP ALT below current altitude,
Early Descent vertical speed commands of -1000 fpm will be generated
by the FMC for autopilot V/S tracking until path intercept or MCP ALT
level off occurs.
September 15, 2016
To Next Page
Loading...
