Boeing 787-8 - Page 1207

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 11.31.21
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 acceleration height or flap retraction, VNAV commands an airspeed increase
to a speed 5 knots below the flap placard speed for the existing flap setting. When
flaps are retracted or at an AFDS capture altitude, VNAV commands the greater
of 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
• default VNAV climb speed
• manually entered climb speed
If the FMC predicts the airplane will not reach an altitude constraint, the
FMS–CDU help window message UNABLE NEXT ALTITUDE displays. Speed
intervention can be used by pushing the IAS/MACH selector and manually setting
a lower airspeed to provide a steeper climb; or, climb derates can be deleted on the
THRUST LIMIT page.
The point where the climb phase meets the cruise altitude is called the top of
climb. Approaching this point, the FMC changes from the climb phase to the
cruise phase. The T/C displays any time the FMC calculates a change from a climb
phase to a cruise phase, such as a step climb.
The T/C point displays on the map as a green open circle with the label T/C.
2
Acceleration Height
3
VNAV Climb
4
Climb Constraints
5
Top Of Climb (T/C)
August 14, 2009