曝光台 注意防骗
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approach waypoint or runway). The VNAV page title changes from
"ACT xxxxx DES" to "ACT END OF DES"
When the FMC is “on approach”, the following features are available:
• the IAS/MACH window can be opened and the command speed can be
set while VNAV remains in VNAV PTH descent; VNAV commands the
set speed
• the MCP altitude can be set above the airplane altitude for the missed
approach. When the MCP altitude setting is at least 300 feet above the
current airplane altitude, VNAV continues to command a descent
• VNAV remains in VNAV PTH and follows the descent path unless the
airplane accelerates to within 5 knots of the current flap placard and the
airplane rises more than 150 feet above the path. In this case, VNAV PTH
changes to VNAV SPD
• When a glide path angle is specified for one or more legs on the approach,
it displays on the LEGS page and VNAV provides VNAV PTH guidance
at the displayed angle. When sequencing a waypoint prior to a descent leg
specified by a glide path angle, VNAV commands level flight until the
airplane intercepts the descent path
Note: Display of a specified glide path angle is not limited to approaches. A glide
path angle may be defined for a leg in a STAR and displays on the LEGS
page for the procedure.
A side step to another approach can be accomplished by selection of the new
approach on the ARRIVALS page. An along-course intercept to the next logical
approach waypoint in the new approach can be selected on the “INTC CRS TO”
line on the LEGS page or by selecting the "XXXXX INTC>" prompt on the
ARRIVALS page.
787 Flight Crew Operations Manual
Flight Management, Navigation -
Flight Management System
Operation
Boeing Proprietary 11.31.27
Missed Approach
A missed approach is accomplished by selection of either TOGA switch. The
following features are available:
• VNAV (and LNAV) can only be activated when the airplane climbs above
400 feet radio altitude
• all descent altitude constraints below the current airplane altitude are
deleted; the waypoints are retained in the active flight plan
• the new cruise altitude becomes the greater of the MCP altitude or the
highest altitude in the missed approach procedure
• the FMC transitions from active descent to active climb. This transition
also occurs when the airplane climbs toward the MCP altitude and flaps
are retracted from a landing position (25 or 30 towards 20, or 20 towards
5). For example, when a missed approach is accomplished without
pushing the TO/GA switch
• AFDS guidance to fly the published missed approach procedure to the
new cruise altitude is active when VNAV (and LNAV) are selected
• when cruise phase is active, the speed target is the most restrictive of 250
knots (below speed transition altitude), best hold speed, or ECON cruise
(above speed transition altitude).
787 Flight Crew Operations Manual
Flight Management, Navigation -
Flight Management System
Operation
11.31.28 Boeing Proprietary
Cruise and Descent Profile
(Instrument Approach Using VNAV)
Before the top of descent, FMC is in cruise mode and commands VNAV PTH and
ECON cruise speed.
1 Cruise
T/D
WAYPOINT
CONSTRAINT
CROSS AT
FAF ALT
AND 170 KTS
50' MISSED APP
ALTITUDE
FAF
NOTE: SELECTION OF TO/GA AFTER
STARTS A MISSED APPROACH
SETS GO-AROUND THRUST
AND DELETES ALTITUDE CONSTRAINTS
THROUGH THE END OF DESCENT
VNAV PTH
VNAV PTH
VNAV PTH
VNAV PTH
VNAV PTH
10,000'
E/D
VNAV SPD
ABOVE 4,000'
CROSS EPG
EPG
THE FLAPS ARE EXTENDED:
2
3
4
6
1
5
787 Flight Crew Operations Manual
Flight Management, Navigation -
Flight Management System
Operation
Boeing Proprietary 11.31.29
Nearing descent speed, VNAV commands a descent in VNAV PTH at ECON
descent speed.
Before the speed restriction altitude, the FMC commands the target descent
airspeed. The pitch mode remains VNAV PTH and the descent rate approximates
500 feet per minute.
When at target speed, VNAV commands a descent and starts approach in VNAV
PTH at commanded speed.
When selected during missed approach, VNAV activates in VNAV SPD.
At missed approach altitude, VNAV SPD changes to VNAV PTH.
2 Descent
3 Descent Deceleration Phase
4 Descent and Approach
5Missed Approach
6Missed Approach Level Off
787 Flight Crew Operations Manual
Flight Management, Navigation -
Flight Management System
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787机组操作手册Flight Crew Operations Manual 3(32)
