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Flight Management System
Operation
Boeing Proprietary 11.31.17
• modifications to an active route display as dashed white lines
• modified waypoints display in white
• executed route offsets display as a dashed magenta line
The ND displays the FMC position at the apex of the airplane symbol. All ND map
data displays relative to this apex.
When adequate GPS or radio updating is not available, the ND map may display
a shift error. This error results in the displayed position of the airplane, route,
waypoints, and navigation aids being shifted from their actual position. An
undetected, across track map shift may result in the airplane flying a ground track
that is offset from the desired track. An undetected, along track map shift may
result in the flight crew initiating altitude changes earlier or later than desired. In
either case, an undetected map shift may compromise terrain or traffic separation.
Map shift errors can be detected by comparing the position of the airplane on the
ND map with data from the ILS, VOR, DME, and ADF systems.
Vertical Navigation (VNAV)
VNAV provides vertical profile guidance through the climb, cruise, and descent
phases of flight.
Speed/Altitude Constraints
VNAV controls the path and speed to comply with waypoint crossing constraints.
Waypoint crossing constraints are entered on the LEGS page waypoint line by
pushing the applicable key on the right side of the CDU. Barometric altitude
constraints must be below the cruise altitude to be valid. Values entered as part of
a procedure and manually entered constraints are shown in large font. FMC
predicted values do not act as constraints, and display in small font.
A waypoint constraint is magenta when it is active. The constraint does not have
to be in line 1 to be active. Waypoints can have altitude or airspeed/altitude
constraints.
Modified waypoint constraints are shaded white until they are executed. Speed
constraint entries require an altitude constraint at the same waypoint. All speed
constraints are considered by the FMC as at or below constraints.
At or above altitude constraints are entered with a suffix letter A (example: 220A).
At or below altitude constraints are entered with a suffix letter B (example: 240B).
Mandatory altitude constraints are entered without any suffix letter (example:
270).
Altitude constraints with two altitudes may be entered in either order. The lower
altitude constraint, followed by a suffix letter A, and the upper altitude constraint,
followed by a suffix letter B (example: 220A240B or 240B220A).
787 Flight Crew Operations Manual
Flight Management, Navigation -
Flight Management System
Operation
11.31.18 Boeing Proprietary
Takeoff and Climb
If armed for takeoff, VNAV activates at 400 feet RA and pitch guidance continues
to maintain the target airspeed.
1 Takeoff
ACCELERATION
VNAV PTH
VNAV
VNAV SPD
VNAV SPD
VNAV PTH
UNABLE NEXT ALT
HELP MESSAGE
ECON CRZ SPD
ECON CLB SPD
CROSS CDE
ABOVE 18,000'
WAYPOINT
CONSTRAINT
CROSS ABC
ABOVE
4,000'
CROSS
BCD AT
6,000'
V2+15
TO V2+25
250 KTS
(OR VREF+80)
250 KTS
ABC BCD 10,000'
CDE
250 KTS
T/C
HEIGHT
ENGAGEMENT
2
4
5
1
3
787 Flight Crew Operations Manual
Flight Management, Navigation -
Flight Management System
Operation
Boeing Proprietary 11.31.19
During takeoff, the FMC updates the target airspeed to the current airspeed until
VNAV activates. The target airspeed is between V2 + 15 and V2 + 25 knots.
At the acceleration height, flap retraction, or AFDS altitude capture before
acceleration height, VNAV commands an airspeed increase to the greater of 250
knots, VREF + 80 knots, or the speed transition associated with the origin airport,
limited by configuration.
The FMC changes the thrust reference mode to the selected climb thrust at the
thrust reduction point.
The VNAV climb profile uses VNAV SPD or VNAV PTH at the default climb
speed or pilot selected climb speed to remain within all airspeed and altitude
constraints that are part of the SID entered into the active route. Autothrottle uses
selected climb thrust limit.
If the climb speed profile cannot achieve an altitude constraint, the UNABLE
NEXT ALT CDU help window message displays.
VNAV enters the VNAV PTH mode to remain within departure or waypoint
constraints. Speed maintained during this time can be:
• procedure based speed restriction
• waypoint speed restriction
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787机组操作手册Flight Crew Operations Manual 3(28)
