737 Operations Manual

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.

Alternates can be selected at any time. Alternates are available from preflight
through all phases of flight and can be updated at any time. Diversion to an
alternate can be accomplished during cruise, descent, or approach.

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 (prior to U10) the CAPTURE or (U10) the DES NOW prompt.
Descent
During descent, LNAV progress is managed using the RTE LEGS and PROGRESS pages, as in the cruise phase. VNAV descent management is accomplished primarily on the DES page.
The DES FORECASTS page is also available to enter forecast wind data to aid in descent planning.
Descent Page (During Cruise)
The descent page is used to monitor, revise, or select the descent path. Descent modes are economy (ECON) path or speed and manual path or speed. The default VNAV descent mode is ECON PATH.
The page title reflects the VNAV descent mode. The path mode controls descent to fly a vertical path which complies with altitude and speed restrictions in the flight plan. The speed mode controls descent at a fixed speed and complies with altitude and speed restrictions in the flight plan.
Flight Management, Navigation -FMC Descent and Approach 737 Operations Manual

Page Title
The page title identifies the selected mode. When a manual speed is selected, the title includes XXXKT for fixed CAS or M.XXX for fixed Mach selections. Displays ACT when the descent phase is active.
Copyright . The Boeing Company. See title page for details.
11.43.2  December 1, 2000

Flight Management, Navigation -FMC Descent and Approach 737 Operations Manual

End of Descent Point (E/D ALT)
Displays the end of descent altitude.
.  
for a PATH DES page, displays the altitude restriction for the E/D
waypoint; blank if path descent not available

.  
for a SPD DES page, displays 1,000 feet above destination airport or, (U5
and on) the lowest “at” altitude constraint, whichever is lower.

.  
(U7 and on) If an approach is selected which ends at RWXXX, the E/D
altitude will be threshold crossing height (TCH), 50 feet above the
runway.

Target Speed (TGT SPD)
Displays the speed used while descending to waypoints, constraints, or speed restrictions:
.  
for ECON PATH or ECON SPD DES, displays the computed values for
target Mach and airspeed, may be performance limited

.  
manual entries may be made and will cause the manual PATH or manual
SPD DES page for that value to display (M.720 SPD DES is depicted)

.
the active controlling speed is highlighted in reverse video

.
blank for any PATH DES page if a path descent is not available.

Speed Restriction (SPD REST)
Displays the most restrictive of the following speeds:
.
destination airport speed minus 10 knots

.  
waypoint speed restriction if greater than minimum flaps up maneuvering
speed

.
minimum flaps up maneuvering speed

.
selected Vref + wind correction for landing flap setting

.  
whenever flaps are extended, the, appropriate flap speed shall be
displayed as XXX/FLAPS. This shall supersede any other speed
restriction

.  
displays XXX/HOLD when decelerating to hold speed prior to hold entry
fix.

Dash prompts displayed when there is no active speed restriction.
Manual crew entries or deletions may be made. HOLD or FLAPS speed may not be deleted or modified.

Economy (ECON)
Displayed on the manual DES pages.
Push – selects the corresponding ECON SPD or ECON PATH DES page.
Flight Management, Navigation -FMC Descent and Approach 737 Operations Manual

Descent Forecasts (FORECAST)
Push – selects the DES FORECASTS page.

PATH
Displayed on the SPD DES pages if a path descent is available. Push – selects the corresponding PATH DES page.

CAPTURE/DES NOW
Displayed on the standard DES pages whenever descent is not ACT or MOD.
Blank for any PATH DES page if a path descent is not available.
　
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