787 Flight Crew Operations Manual
DO NOT USE FOR FLIGHT
Flight Management, Navigation -
Flight Management System
Operation
Copyright © The Boeing Company. See title page for details.
D615Z003-TBC 11.31.27
Use the DES NOW prompt on the VNAV DES page. VNAV starts an early descent
and captures the descent path.
Use the MCP altitude selector to start an early descent. Within 50 NM of the top
of descent point, VNAV starts an early descent and captures the descent path.
Use the MCP altitude selector to start a cruise descent. If the distance from the top
of descent is more than 50 NM, VNAV begins a cruise descent to the new cruise
altitude. VNAV may not capture the descent path since the target airspeed is
economy cruise and the descent path is based on off-idle thrust and economy
descent airspeed. In the example, VNAV levels at the new cruise altitude.
Approach
The FMC transitions to "on approach" mode for any of the following conditions:
• the descent phase is active and flaps are out of UP, or
• the airplane has sequenced the first waypoint (or FAXXX) of the active
approach, or
• the airplane is on a direct-to intercept course-to the active waypoint and the
distance to go is less than 12 NM, or
• the missed approach point is the active waypoint and the distance to go is
less than 25 NM
1
DES NOW
2
Within 50 NM of Top of Descent Point
3
More than 50 NM from Top of Descent Point
T/D
1
T/D
50 NM
2
50 NM
T/D
Old CRZ Altitude
New CRZ Altitude
T/D
3
August 14, 2009
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