737 MAX Flight Crew Operations Manual
Flight Management, Navigation
Chapter 11
FMC Descent and Approach
Section 43
MN-FLT-OH-201
11.43.1
43 FMC Descent and Approach
FMC Descent and Approach
File Highlight
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.
A CRZ DES occurs when 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.
• 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, or by entering a new cruise altitude on the FMC CRZ page after
setting the new level-off altitude in the MCP.
• Altitude Intervention may be used to initiate Early Descent when the
airplane is 50 nm or less fromT/D.
• If Altitude Intervention is used to initiate descent when 50 NM or less to
T/D and the MCP ALT below current altitude, or descent is initiated via
DES NOW prompt on the DES page, Early Descent vertical speed
commands of -1000 fpm are generated by the FMC for autopilot V/S
tracking until path intercept, or next constraint altitude if altitude is
reached when VNAV is engaged, or MCP ALT level off occurs.
• If Altitude Intervention is used to initiate descent when more than 50
NM to T/D with VNAV engaged and the MCP ALT below current
altitude but at or above any descent constraint altitude, the result will be
cruise altitude reset to the MCP ALT and Cruise Descent vertical speed
commands of -1000 fpm to the new cruise altitude.
• If Altitude Intervention is used to initiate descent when more than 50
NM to T/D with VNAV engaged and the MCP ALT below current
altitude and below a descent constraint altitude, the result will be Early
Descent vertical speed commands of -1000 fpm until path intercept or
MCP ALT level off occurs.
March 1, 2021
