Garmin GNC 420 Installation and operating instructions

190-00181-15 REV. A
400/500 SERIES
PILOT’S GUIDE ADDENDUM
Fault Detection and Exclusion (FDE) Interface
NOTE: This addendum assumes the user has experience operating the applicable 400/500 Series Unit and is familiar
ith the operation of RAIM. The fi gures in this Addendum apply to the GNS 430. The same information applies to the
other 400/500 units unless other ise stated.
FAULT DETECTION AND EXCLUSION (FDE)
The GARMIN 400/500 Series Main and GPS Sof ware version 3.00 and higher (Figure 1) incorpora e Faul De ec ion and
Exclusion (FDE) display in erface and con rol, sa isfying he requiremen s for “GPS as a Primary Means of Naviga ion for
Oceanic/Remo e Opera ions” per FAA No ice N8110.60.
FDE consis s of wo dis inc par s, faul de ec ion and faul exclusion. The faul de ec ion par de ec s he presence of an
unaccep ably large pseudorange error (and presumably, posi ion error) for a given mode of fl igh . Upon he de ec ion, faul
exclusion follows and excludes he source of he unaccep ably large pseudorange error, hereby allowing naviga ion o re urn
o normal performance wi hou an in errup ion in service. To enhance safe y, FDE func ionali y is provided for o her phases
of fl igh (non-precision approach, erminal, en rou e). The FDE func ionali y for non-oceanic fl igh phases adheres o he
same missed aler probabili y, false aler probabili y, and failed exclusion probabili y specifi ed by N8110.60.
The following 400/500 Series Uni s are affec ed:
• GPS 400
• GNC 420/420A
• GNS 430/430A
• GPS 500
• GNS 530/530A
Figure 1.
PRE-DEPARTURE VERIFICATION OF FDE
An FDE predic ion mus be performed prior o depar ure for a fl igh plan involving Oceanic/Remo e opera ion where GPS
is o be he sole source of naviga ion. Prior o depar ure, he opera or mus use he FDE Predic ion Program supplied wi h
he 400/500 Trainer Sof ware o demons ra e ha here are no ou ages in he capabili y o naviga e on he specifi ed rou e of
fl igh ( he FDE Predic ion Program de ermines whe her he GPS cons ella ion is robus enough o provide a naviga ion solu-
ion for he specifi ed rou e of fl igh ). Refer o he ins ruc ions ha came wi h your 400/500 Trainer Sof ware for comple e
de ails on using he FDE Predic ion Program.

FDE INTERFACE AND CONTROL
• RAIM Prediction—TheRAIM predic ion user-in erface remains he same for all uni s in he 400/500 Series.
RAIM is an acronym for Receiver Au onomous In egri y Moni oring, a GPS receiver func ion ha performs a
consis ency check on all racked sa elli es. RAIM ensures ha he available sa elli e geome ry will allow he receiver
o calcula e a posi ion wi hin a specifi ed pro ec ion limi (2 nau ical miles for oceanic and en rou e, 1 nm for
erminal, and 0.3 nm for non-precision approaches).
During oceanic, en rou e and erminal phases of fl igh will be available nearly 100% of he ime. Because of he
igh er pro ec ion limi s on approaches, here may be imes when RAIM is no available. The 400/500 Series Uni
au oma ically moni ors RAIM and will warn you wi h an aler message (see he applicable Pilo ’s Guide) when i
is no available, and he INTEG annuncia or will appear a he bo om lef corner of he screen. If RAIM is no
available when crossing he FAF, he pilo mus fl y he missed approach procedure. The uni ’s RAIM predic ion
func ion will also allow you o see whe her RAIM will be available for a specifi ed da e and ime. NOTE: If RAIM is
not predicted to be available for the fi nal approach course, the approach ill not become active-as indicated
by an “Approach is not active” message, a “RAIM not available from FAF to MAP” message and the INTEG
annunciator.
• CDI/A arms—allows you o defi ne he scale for he GNS 430’s on-screen course devia ion indica or. The scale
values represen full scale defl ec ion for he CDI o ei her side. The defaul se ing is “Au o”. A his se ing, he
CDI scale is se o 5 nm during he en rou e and oceanic/remo e phases of fl igh . Wi hin 30 nm of your des ina ion
airpor he CDI scale gradually ramps down o 1.0 nm ( erminal area). Likewise when leaving your depar ure
airpor he CDI scale is se o 1.0 nm and gradually ramps up o 5 nm beyond 30 nm (from he depar ure airpor ).
Oceanic fl igh phase (OCN) begins when he aircraf is more han 200 nm from he neares airpor .
During approach opera ions he CDI scale gradually ramps down even fur her, o 0.3 nm. This ransi ion normally
occurs wi hin 2.0 nm of he fi nal approach fi x (FAF). If a lower CDI scale se ing is selec ed (i.e., 1.0 nm or 0.3
nm) he higher scale se ings will no be selec ed during ANY phase of fl igh . For example, if 1.0 nm is selec ed,
he GNS 430 will use his for he en rou e and erminal phase and ramp down o 0.3 nm during an approach.
No e ha he Receiver Au onomous In egri y Moni oring (RAIM) pro ec ion limi s lis ed below follow he selec ed
CDI scale and corresponding modes:
CDI Sca e RAIM Protection (no display)
Au o (oceanic) 4.0 nm
±5.0 nm or Au o (en rou e) 2.0 nm
±1.0 nm or Au o ( erminal) 1.0 nm
±0.3 nm or Au o (approach) 0.3 nm
An “Au o” ILS CDI selec ion allows he GNS 430 o au oma ically swi ch he ex ernal CDI from he GPS receiver
o he VLOC receiver, when es ablished on he fi nal approach course. Or, selec “manual” o manually swi ch he
ex ernal CDI connec ion, as needed. An arrival alarm, provided on he CDI / alarms page, may be se o no ify
you wi h a message when you have reached a user-defi ned dis ance o he fi nal des ina ion ( he direc - o waypoin
or he las waypoin in a fl igh plan). Once you have reached he se dis ance (up o 99.9 uni s), an “Arrival a
[waypoin ]” message will be displayed.
Figure 2. CDI Enroute/Oceanic (OCN) Scale
190-00181-15 Rev. A

CDI SCALE CHANGE
The GNS 430 will begin a smoo h CDI scale ransi ion from he 5.0 nm (enrou e/oceanic mode) o he 1.0 nm ( erminal
mode) scale 30 nm from he des ina ion airpor (see Figure 2). The CDI scale will fur her ransi ion o 0.3 nm (approach
mode) a 2 nm prior o he FAF during an ac ive approach. If you are in a missed approach si ua ion, and would like o
re urn he CDI o he 1 nm scale, ac iva e he missed approach sequence by pressing he OBS key. The CDI scale will also be
1.0 nm ( erminal mode) wi hin 30 nm of he depar ure airpor .
Figure 2. CDI Scale Transition
SATELLITE STATUS PAGE
The Sa elli e S a us Page in Figure 3 shows sa elli e number 9 exclusion during oceanic phase of fl igh . No message no ifying
he user of exclusion appears. In addi ion o he EPE and DOP fi elds, here is he Horizon al Uncer ain y Level (HUL) fi eld
which displays a 99% confi dence level ha he aircraf posi ion is wi hin a circle wi h radius of he value displayed in he
HUL fi eld.
NAV Terms
The following acronyms have been added o each of he 400/500 Pilo ’s Guides: FDE-Faul De ec ion and Exclusion; and
OCN-oceanic.
0.3 nm
30 nm
2nm
FAF
MAP
1 nm
1 nm
5nm
1 minute
APPROACH
TERMINAL
ENROUTE/OCEANIC
Excluded Satellite (chec ed pattern)
Oceanic Mode Annunciation (OCN)
Horizontal Uncertainty Level
Figure 3. Satellite Status Page
190-00181-15 Rev. A

190-00181-15 Rev. A
© Copyrigh 2002
GARMIN L d. or i s subsidiaries
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GARMIN Corpora ion
No. 68, Jangshu 2nd Road, Shijr, Taipei Coun y, Taiwan