FLIGHT PHASES
DESCENT 9
Vertical guidance
Managed DESCENT mode (DES)
Managed DES mode is only available with NAV mode engaged.
In DES mode the FMGC computes an optimized vertical profile
backwards from the destination runway threshold, missed approach
point, or final end-point, to the top of descent taking into account any
speed and/or altitude constraints entered in ACTIVE F-PLN and CABIN
RATE selected on CRZ PERF page.
Vertical profile is computed so as to maintain the ECON speed (or pilot-
entered speed) with idle thrust (fuel optimized descent).
Re-pressurization segment (when needed), deceleration, geometric
segments (not necessarily at idle thrust) are included in the descent
profile.
The vertical profile is recomputed if revisions are entered in ACTIVE F-
PLN.
Actual position relative to the
computed vertical profile may
be monitored:
DESCENT THV001
CRZ OPT REC MAX
----- ----- FL393
<REPORT VDEV=- 00 FT
UPDATE AT
*[ ]
BRG /DIST
314° /92.5 TO EGLL27R
PREDICTIVE
<GPS GPS PRIMARY
REQUIRED ACCUR ESTIMATED
2.0NM HIGH 0.08NM
− On PFD by vertical deviation
symbol (magenta circle).
The range is ± 500 feet;
when the VDEV value
exceeds ± 500 feet, the
symbol stays at the range
limit.
− On PROG page by VDEV
[2R].
Selected vertical modes (OP DES – V/S)
The vertical profile is not maintained by the FMGS.
In OP DES mode, descent is IDLE thrust maintaining target speed.
In V/S mode, thrust is adjusted to maintain target speed; if idle thrust
is not enough to assure V/S requested, target speed is not maintained.
Actual position
relative to the
computed vertical
profile may be
monitored as above.
DESCENT THV001
CRZ OPT REC MAX
----- ----- FL393
<REPORT VDEV=+ 270 FT
UPDATE AT
*[ ]
BRG /DIST
313° /89.1 TO EGLL27R
PREDICTIVE
<GPS GPS PRIMARY
REQUIRED ACCUR ESTIMATED
2.0NM HIGH 0.08NM
AIRBUS A318/319/320/321
© THALES AVIONICS S.A.
J43126AA 00
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