Thales FMGS - Descent; Alternate WINDS; MCDU Preparation; Preparation for Descent and Approach

FLIGHT PHASES
CRUISE 17
5.6. PREPARATION FOR DESCENT AND APPROACH
 Descent / Alternate WINDS
Insertion or updating of Descent/Alternate winds is recommended.
If no wind is inserted for descent, FMGC will assume linear variation
from the existing cruise wind to the entered wind on approach page.
In this case, the computed profile is not optimum if assumed wind
component is significantly different. For example:
− If tailwind component is greater than assumed, steep descent
requiring extra drag can be anticipated,
− If headwind component, additional thrust needed and fuel penalty
will occur.
Alternate wind affects fuel predictions and reserve calculation.
The WIND DATA function is described in Part III: Ch 4.2.
 MCDU preparation
The MCDU preparation for descent and approach is described here in
the following sequence:
− F-PLN page A
− FUEL PRED page
− RAD NAV page
− PROG page
− PERF page
− SEC F-PLN
AIRBUS A318/319/320/321
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