OPERATIONS MANUAL

FMS
Waypoint WIND Page:
1L
2L
3L
4L
1R
2R
3R
4R
Access:
1R, 2R, 3R, 4R, 5R on RTE DATA.
General:
Displays forecast winds and temperatures
at a route waypoint, used by the FMC
to improve performance prediction
calculations. Data can be modified by
manual entries or by ACARS uplinks.
1L 2L 3L 4L ALT OAT
Displays up to four altitudes. Deletion is
allowed in all four lines. Entry is allowed
in 1L when dashes are shown. Altitudes
are automatically sorted in 1L through 4L,
and appear on all pages.—In the middle of
a line, the OAT at the respective altitude is
shown if an OAT reference is entered in 5R.
The FMC propagates this OAT reference
vertically to the other altitudes at this
waypoint, based on standard temperature
lapse rates.—OAT and wind data at each
altitude are propagated horizontally to
adjacent waypoints if an adjacent waypoint
contains no entered data. Propagated
data are displayed in small font, entered
data in large font.—For the performance
predictions, the FMC uses a mixing algorithm,
taking into account the forecast wind
and the current IRS computed wind. For the
present position the FMC uses 0% forecast
wind and 100% IRS wind. Along the route,
the ratio gradually reverses to 100% forecast
with 0% IRS wind. The ratio is 50% to 50%
at 200 nm ahead of the aircraft. During
climb and descent, the algorithm is based
on vertical distances: in climb, the 50% to
50% point is at 5000 ft above the aircraft; in
descent 5000 ft below it. The FMC applies
this algorithm also for forecast OATs and
the current ADC computed SAT.
1R 2R 3R 4R DIR/SPD
Displays the forecast wind at the respective
altitude. Data entries are displayed in large
font, propagated data in small font. If no
wind entry and no propagated data exist,
dashes are displayed; in that case, the
FMC will interpolate the data internally as
follows: winds above the highest altitude
entry are all equal; for winds below the
lowest altitude entry, wind directions
are all equal, with wind speeds gradually
decreasing to 0 kt at destination elevation,
or at MSL if a destination is not entered.
Valid entries
Wind speed (0 to 250 kt) if direction is
already entered:
X
XX
XXX
Wind direction (0° to 360°) if speed is
already entered:
XXX/
Wind direction/wind speed:
XXX/X
XXX/XX
XXX/XXX
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