Descent

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The descent page is used to monitor and revise the descent path. Descent speed modes are economy (ECON) and fixed speed (SEL). The default VNAV descent mode is ECON. A fixed speed descent is flown when speed intervention is used or a speed is entered on the DES page. The descent page is no longer available after the end of descent.

The page title includes the VNAV speed mode. The ECON mode controls descent speed at the economy speed until reaching a lower speed restriction. The fixed speed mode controls descent speed until a lower speed restriction is reached.

Page Title - The title usually shows ECON during descent. Fixed speed descents modify the title. The page title shows the type of descent:

  • ECON - speed based on a cost index
  • LIM SPD - speed based on airplane configuration limiting speed
  • MCP SPD - MCP speed intervention is selected
  • XXXKT - fixed CAS descent speed profile
  • M.XXX - fixed Mach descent speed profile
  • ACT - prefix shown when descent phase is active
  • MOD - prefix shown when descent phase is active and the flight plan is modified


Reasons for fixed descent speeds are:

  • waypoint speed constraints
  • an altitude constraint associated with a speed constraint
  • a speed transition
  • a flight crew entered selected speed (SEL SPD).
E/D AT - Shows the end of descent altitude and waypoint. The end of descent point is a waypoint in the descent phase with the lowest altitude constraint. Blank if no E/D point exists.
ECON SPD or SEL SPD - Shows the current target descent speed.

ECON SPD
  • economy speed based on cost index
  • shows CAS or Mach


SEL SPD -
  • shows when intermediate level off required below an existing speed constraint
  • shows when flight crew enters speed
  • CAS or Mach value may be entered.
  • page title changes to ACT XXXKT DES or ACT M.XXX DES
  • < ECON prompt appears at line 51- to allow selection of economy descent speed
SPD TRANS - The transition speed is usually 10 knots less than the destination airport limiting speed from the navigation database. When no airport limit speed exists, the default speed of 240 knots is shown. The transition altitude is the point that the transition speed is active for the destination airport. When no altitude exists in the navigation database, the default of 10,000 feet is shown. Blanks when the transition has occurred. Can be deleted.
SPD RESTR - Speed restrictions not associated with specific waypoints are manually entered on this line. Dashes before entry by flight crew. Valid entry is a CAS and altitude (example 240/8000). An entry creates a modification.
ECON - Selects economy descent speed. Blank when economy is the active descent speed.
OFFPATH DES (PEGASUS only) Shows the OFFPATH DES page.
AT XXXXX - Shows the next waypoint constraint from the RTE LEGS page.

Line title shows:
  • AT XXXXX (the waypoint identifier)
  • HOLD AT XXXXX
  • AT VECTORS
  • AT (INTC).


The constraint is speed/altitude. Blank when no constraint exists. Can be deleted on this page.

VNAV commands the lesser of constraint speed or present performance speed.
FORECAST - Shows the DESCENT FORECAST page.
DES NOW - Shown when the descent phase is not active. Push:

  • starts a 1250 feet per minute descent schedule until intercepting the planned descent path
  • activates the FMC descent phase


DES DIR - Deletes all waypoint altitude constraints between the airplane altitude and the MCP altitude. Shown in descent phase with altitude constraint between airplane and E/D.

Engine Out Descent

There are no specific engine out pages for descent. Use the all engine descent planning features and pages.

Standard | 11.43.2 | OFFPATH>