Garmin GNC 420AW GPS Receiver User Manual


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2 - NAV PAGES
56
190-00356-00 Rev E
Satellite Status Page
•3DNavigation —
TheGPSreceiverisin3Dnavigationmodeand
computes altitude using satellite data.
•3DDifferentialNavigation—TheGPSreceiveris
in3Dnavigationmodeanddifferentialcorrections
are being used.
The Satellite Status Page also indicates the accu-
racy of the position fix, using Horizontal Figure of
Merit (HFOM),VerticalFigureofMerit(VFOM), and
Estimated Position Uncertainty (EPU). HFOM and
VFOMrepresentthe95%condencelevelsinhori-
zontal and vertical accuracy. The lowest numbers are
the best accuracy and the highest numbers are worse.
EPU is the horizontal position error estimated by the
FaultDetectionandExclusion(FDE) algorithm, in feet
or meters.
NOTE Operating outside of an SBAS service
area with SBAS enabled may cause elevated EPU
values to be displayed on the satellite status
page. Regardless of the EPU value displayed, the
INTEG annunciation is the controlling indication
for determining the integrity of the GPS naviga-
tion solution.
Vertical Navigation Page
WARNING: VNAV is to be used for advisory
purposes only. VNAV messages or vertical speed
required should not be used to maintain terrain
or ATC clearances. Terrain and ATC clearances are
the sole responsibility of the pilot.
The 400W-series vertical navigation page (the last
NAVpage)allowsyoutocreateathree-dimensional
profile which guides you from your present position
and altitude to a final (target) altitude at a specified
location. This is helpful when you’d like to descend
to a certain altitude near an airport. Once the profile
is defined, message alerts and additional data on the
defaultNAVandmappageswillkeepyouinformedof
your progress.
Altitude Reference
(AGL or MSL)
Target
Altitude
Target
Distance
Page location in
NAV group
Vertical Speed
Desired
Target Reference
Vertical Speed
Required
VNAV is inhibited in the following conditions:
• Groundspeedislessthan35knots
• Noactiveightplanordirect-todestination
• SUSPmode
• Vectors-to-Finalmode
• VLOCmode
• AftertheFAFonanapproach
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