Garmin GNC 420 User manual

GNC 420/420A
Pilot’s Guide and Reference
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GNC 420 RevC prelim.indd ii 5/19/2003, 9:02:39 AM

i
INTRODUCTION
Foreword
This manual reflects the operation of Main System Software version 4.00. Some differ-
ences may be observed when comparing the information in this manual to other software
versions.
Garmin International, Inc., 1200 E. 151st Street, Olathe, Kansas 66062 USA
Tel: [phone] Fax: [phone]
Garmin (Europe) Ltd., Unit 5, The Quadrangle, Abbey Park, Romsey, Hampshire S051 9DL, UK
Tel: [phone]
Fax: [phone]
Garmin (Asia) Corp., No. 68, Jangshu 2nd Road, Shijr, Taipei County, Taiwan
Tel: [phone] Fax: [phone]
Web Site address: www.garmin.com
© 1999-2003 Garmin Ltd. or its subsidiaries. All rights reserved. Except as expressly
provided herein, no part of this manual may be reproduced, copied, transmitted, dis-
seminated, downloaded or stored in any storage medium, for any purpose without the
express prior written consent of Garmin. Garmin hereby grants permission to download
a single copy of this manual and of any revision to this manual onto a hard drive or other
electronic storage medium to be viewed and to print one copy of this manual or of any
revision hereto, provided that such electronic or printed copy of this manual or revision
must contain the complete text of this copyright notice and provided further that any
unauthorized commercial distribution of this manual or any revision hereto is strictly
prohibited.
Information in this document is subject to change without notice. Garmin reserves
the right to change or improve their products and to make changes in the content of
this material without obligation to notify any person or organization of such changes or
improvements.
May 2003 190-00140-20 Rev. C
Visit the Garmin web site for the latest updates
and supplemental information concerning the
operation of this and other Garmin products.
Garmin®, AutoLocate®, and PhaseTrac12®are
registered trademarks and GNC 420™ amd
Spell’N’Find™ are trademarks of Garmin Ltd.
or it’s subsidiaries and may not be without the
express permission of Garmin.
NavData® is a registered trademark of Jeppesen,
Inc.
GNC 420 RevC prelim.indd i 5/19/2003, 9:02:39 AM

CAUTION
The Global Positioning System is operated by the United States government, which
is solely responsible for its accuracy and maintenance. The system is subject to changes
which could affect the accuracy and performance of all GPS equipment. Although the
Garmin GNC 420 is a precision electronic NAVigation AID (NAVAID), any NAVAID can
be misused or misinterpreted and therefore become unsafe.
Use the GNC 420 at your own risk. To reduce the risk of unsafe operation, care-
fully review and understand all aspects of this Owner’s Manual and the Flight Manual
Supplement, and thoroughly practice basic operation prior to actual use. When in actual
use, carefully compare indications from the GNC 420 to all available navigation sources,
including the information from other NAVAIDS, visual sightings, charts, etc. For safety,
always resolve any discrepancies before continuing navigation.
The altitude calculated by the GNC 420 is geometric height above mean sea level and
could vary significantly from altitude displayed by pressure altimeters in aircraft. GPS
accuracy may be degraded by the U.S. Department of Defense imposed Selective Avail-
ability (SA) program. With “SA” on, GPS altitude may be in error by several hundred
feet. Never use GPS altitude for vertical navigation.
GPS receivers operate by receiving and decoding very low power radio signals
broadcast by satellites. It is possible that in some situations other radio equipment or
electronic equipment used in close proximity to a GPS receiver may create electromag-
netic interference (EMI) which may affect the ability of the GPS receiver to receive and
decode the satellite signals. In such event, the interference may be reduced or eliminated
by switching off the source of interference or relocating equipment.
The Jeppesen database incorporated in the GNC 420 must be updated regularly in
order to ensure that its information is current. Updates are released every 28 days. A
database information packet is included in your GNC 420 package.
Pilots using an out-of-date database do so entirely at their own risk.
ii
NOTE: This device complies with Part 15 of
the FCC limits for Class B digital devices. This
equipment generates, uses, and can radiate radio
frequency energy and, if not installed and used
in accordance with the instructions, may cause
harmful interference to radio communications. Fur-
thermore, there is no guarantee that interference
will not occur in a particular installation.
If this equipment does cause harmful interfer-
ence, the user is encouraged to try to correct the
interference by relocating the equipment or con-
necting the equipment to a different circuit than the
affected equipment. Consult an authorized dealer
or other qualified avionics technician for additional
help if these remedies do not correct the problem.
Operation of this device is subject to the follow-
ing conditions: (1) This device may not cause harm-
ful interference, and (2) this device must accept any
interference received, including interference that
may cause undesired operation.
The Garmin GNC 420 does not contain any
user-serviceable parts. Repairs should only be
made by an authorized Garmin service center.
Unauthorized repairs or modifications could void
your warranty and authority to operate this device
under Part 15 regulations.
INTRODUCTION
Cautions
GNC 420 RevC prelim.indd ii 5/19/2003, 9:02:43 AM

Accessories & Packing List
Congratulations on choosing the finest, most advanced panel mount IFR navigation/
communication system available. The GNC 420 represents Garmin’s commitment to
provide accurate, easy-to-use avionics for all of your flying needs.
Before installing and getting started with your unit, please check to see that your pack-
age includes the following items. If any parts are missing or damaged, please see your
Garmin dealer immediately.
Standard Package:
• GNC 420 Unit & NavData® Card
• Installation Rack & Connectors & GPS Antenna
• Pilot’s Guide & Quick Reference Guide
• Database Subscription Packet
• Warranty Registration Card
• GNC 420 Simulator CD-ROM
• 400/500 Series Display Interfaces Pilot’s Guide Addendum
Your Garmin dealer will perform the installation and configuration of your new
GNC 420. After installation, the NavData® card will already be installed into the cor-
rect slot on the front of the unit (see Appendix A). The GNC 420 will be secured in the
installation rack with the proper wiring connections performed. Have your dealer answer
any questions you may have about the installation—such as location of antennas or any
connections to other equipment in the panel.
Unless otherwise specified within this manual, the term "GNC 420" applies to both the
GNC 420 and the GNC 420A models. Please, note that the difference between these two
models is indicated under "VHF COM Performance" in the Specifications section of this
manual (see Appendix B).
iii
INTRODUCTION
Accessories and
Packing List
Notes
The GNC 420 display lens is coated with a special
anti-reflective coating which is very sensitive to
skin oils, waxes, and abrasive cleaners. CLEAN-
ERS CONTAINING AMMONIA WILL HARM
THE ANTI-REFLECTIVE COATING. It is very
inportant to clean the lens using an eyeglass lens
cleaner which is specified as safe for anti-reflective
coatings and a clean, lint-free cloth.
Help us to better support you by completing our
on-line registration today! Registration ensures you
will be notified of product updates, new products
and provides for lost or stolen unit tracking. Have
the serial number of your GNC 420 handy and
connect to our website (www.garmin.com). Look
for the Product Registration link on the home page.
GNC 420 RevC prelim.indd iii 5/19/2003, 9:02:44 AM

This Garmin product is warranted to be free from defects in materials and workman-
ship for one year from the date of purchase. Within this period, Garmin will at its sole
option, repair or replace any components that fail in normal use. Such repairs or replace-
ment will be made at no charge to the customer for parts or labor, provided the customer
shall be responsible for any transportation costs. This warranty does not cover failures due
to abuse, misuse, accident or unauthorized alteration or repairs.
THE WARRANTIES AND REMEDIES CONTAINED HEREIN ARE EXCLU-
SIVE, AND IN LIEU OF ALL OTHER WARRANTIES EXPRESSED OR IMPLIED,
INCLUDING ANY LIABILITY ARISING UNDER WARRANTY OF MERCHANT-
ABILITY OR FITNESS FOR A PARTICULAR PURPOSE, STATUTORY OR OTHER-
WISE. THIS WARRANTY GIVES YOU SPECIFIC LEGAL RIGHTS, WHICH MAY
VARY FROM STATE TO STATE.
IN NO EVENT SHALL GARMIN BE LIABLE FOR ANY INCIDENTAL, SPE-
CIAL, INDIRECT OR CONSEQUENTIAL DAMAGES, WHETHER RESULTING
FROM THE USE, MISUSE OR INABILITY TO USE THIS PRODUCT OR FROM
DEFECTS IN THE PRODUCT. Some states do not allow the exclusion of incidental or
consequential damages, so the above limitations may not apply to you.
Garmin retains the exclusive right to repair or replace the unit or software or offer a
full refund of the purchase price at its sole discretion. SUCH REMEDY SHALL BE
YOUR SOLE AND EXCLUSIVE REMEDY FOR ANY BREACH OF WARRANTY.
To obtain warranty service, call your local Garmin Authorized Service Center. For
assistance in locating a Service Center near you, call Garmin Customer Service at the
number listed to the left.
Products sold through online auctions are not eligible for rebates or other special
offers from Garmin. Online auction confirmations are not accepted for warranty verifica-
tion. To obtain warranty service, an original or copy of the sales receipt from the original
retailer is required. Garmin will not replace missing components from any package
purchased through an online auction.
iv
INTRODUCTION
Warranty
Garmin is fully committed to your satisfaction
as a customer. If you have any questions
regarding the GNC 420, please contact our
customer service department at:
Garmin International, Inc.
1200 East 151st Street
Olathe, KS 66062-3426
[phone]
FAX [phone]
This product, its packaging, and its compo-
nents contain chemicals known to the State
of California to cause cancer, birth defects,
or reproductive harm. This Notice is being
provided in accordance with California’s
Proposition 65. If you have any questions or
would like additional information, please refer
to our web site at www.garmin.com/prop65.
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PART ONE: INTRODUCTION
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i
Cautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ii
Accessories/Packing List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .v-vi
Takeoff Tour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-20
PART TWO: REFERENCE
Section 1: Communicating with the GNC 420 . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
COM frequencies
Active and standby frequencies
Section 2: NAV Page Group (GPS navigation) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Using page groups and selecting the desired page
Using the default NAV and map pages
Section 3: Direct-to Navigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Using the
D
key
Section 4: Flight Plans (
F
key and FPL page group) . . . . . . . . . . . . . . . . . . . 54
Creating and using flight plans
Retrieving and editing stored flight plans
Section 5: Approaches, Departures and Arrivals (
P
key) . . . . . . . . . . . . . . . . 66
Selecting and flying non-precision/precision approaches
Selecting and using departures (SIDs) and arrivals (STARs)
v
INTRODUCTION
Table of Contents
CONVENTIONS USED IN THIS MANUAL
A circled number (e.g.,“u”) will appear next
to many of the illustrations shown along the
side of a page. This number refers back to
a specific step on the same page (or in rare
instances, to a step on the following page).
When more than one option is possible within
a procedure, the procedures are described
using an “a”/“b” convention with the same
numbering (e.g., “3a” and “3b” for two options
in step 3). This same convention is used on
pages where there are illustrations referenced
in procedures (e.g.,“pa” and “pb”).
A highlighted “NOTE” area appears on many
pages to point out additional information or
items of particular importance related to a
given subject.
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Section 6: WPT Page Group (Waypoint/database information) . . . . . . . . . . . . . . 86
Finding and viewing airport location, runway and frequency data
Finding and viewing navaid information
Creating user-defined waypoints
Section 7: NRST Page Group (Nearest airports, etc.) . . . . . . . . . . . . . . . . . . . . . 111
Viewing nearest listings for airports, navaids and airspaces
Displaying frequencies for nearest flight service (FSS) and center
Section 8: AUX Page Group (Flight Planning and Unit Settings) . . . . . . . . . . . 123
Section 9: FDE (Fault Detection & Exclusion) . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Section 10: Messages, Abbreviations & Navigation Terminology . . . . . . . . . . . . 151
Appendix A: NavData®Card Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
Appendix B: Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
Appendix C: Map Datums . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Appendix D: Troubleshooting Q & A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
Appendix E: Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
vi
To quickly and easily locate information
on specific tasks, please refer to the Index
on page 173.
INTRODUCTION
Table of Contents
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1
Key and Knob Functions
The GNC 420 is designed to make operation as simple as possible. The key and knob
descriptions on the next three pages provide a general overview of the primary function(s)
for each key and knob. This Takeoff Tour section is intended to provide a brief overview
of the primary functions of your GNC 420. Experiment with the unit and refer to the
Reference sections for more information.
Left-hand Keys and Knobs
The COM power/volume knob controls unit power and communications radio-
volume. Press momentarily to disable automatic squelch control.
The large left knob is used to tune the megahertz (MHz) value of the standbyfre-
quency for the communications transceiver.
The small left knob is used to tune the kilohertz (kHz) value of the standby fre-
quency for the communications transceiver.
The COM flip-flop key is used to swap the active and standby COM
frequencies. Press and hold to select emergency channel (121.500 MHz).
Right-hand Keys and Knobs
The range key allows you to select the desired map scale. Use the up arrow side
of the key to zoom out to a larger area, or the down arrow side to zoom in to a
smaller area.
The direct-to key provides access to the direct-to function, which allows you to
enter a destination waypoint and establishes a direct course to the selected desti-
nation. See Section 3.
TAKEOFF TOUR
Key and Knob
Functions
Left-hand Keys and Knobs
Right-hand Keys and Knobs
R
D
A
W
k
NRST
GNC 420
v
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2
The menu key displays a context-sensitive list of options. This options list allows
you to access additional features or make settings changes which relate to the
currently displayed page.
The clear key is used to erase information or cancel an entry. Press and hold this
key to immediately display the Default Navigation Page (see pages 10 and 26),
regardless of which page is currently displayed.
The enter key is used to approve an operation or complete data entry. It is also
used to confirm information, such as during power on.
The large right knob (CRSR) is used to select between the various page groups:
NAV, WPT, AUX or NRST. With the on-screen cursor enabled, the large right
knob allows you to move the cursor about the page.
The small right knob (CRSR) is used to select between the various pages within
one of the groups listed above. Press this knob momentarily to display the on-
screen cursor. The cursor allows you to enter data and/or make a selection from a
list of options.
Data is entered using the large and small
knobs. Experiment with them to become
efficient at entering data. This will greatly
reduce the amount of time spent operating
the GNC 420 in flight.
TAKEOFF TOUR
Key and Knob
Functions
m
c
E
d
a
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3
TAKEOFF TOUR
Key and Knob
Functions
Bottom Row Keys
The NRST key displays the nearest airports page. Then, rotating the small
right knob (
a
) steps through the NRST pages.
The OBS key is used to select manual or automatic sequencing of waypoints.
Pressing the OBS key selects OBS mode, which will retain the current “active
to” waypoint as your navigation reference even after passing the waypoint (i.e.,
prevents sequencing to the next waypoint). Pressing the OBS key again will
return to normal operation, with automatic sequencing of waypoints. Whenever
OBS mode is selected, you may set the desired course to/from a waypoint using
the OBS Page, or an external OBS selector on your HSI or CDI.
The message key is used to view system messages and to alert you to important
warnings and requirements. See Sections 8 and 9 for more information on mes-
sages and unit settings.
The flight plan key allows you to create, edit, activate and invert flight plans, as
well as access approaches, departures and arrivals. A closest point to flight plan
feature is also available from the flight plan key. See Section 4 for more informa-
tion on flight plans.
The procedures key allows you to select and remove approaches, departures and
arrivals from your flight plan. When using a flight plan, available procedures for
your departure and/or arrival airport are offered automatically. Otherwise, you
may select the desired airport, then the desired procedure.
Whenever the GNC 420 is displaying a list
of information that is too long for the display
screen, a scroll bar will appear along the
right-hand side of the display. The scroll bar
graphically indicates the number of additional
items available within the selected category.
Simply press the small right knob (a) to acti-
vate the cursor and rotate the large right knob
(d) to scroll through the list.
N
O
F
M
P
}
scroll bar
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4
TAKEOFF TOUR
Power On
The Garmin GNC 420 provides you accurate navigational data and communication
capability, along with non-precision approach certification in the IFR environment. The
Takeoff Tour is designed to familiarize you with the operation of the GNC 420—includ-
ing powering up the unit, changing frequencies, entering data, performing a simple
direct-to, selecting IFR procedures and provides a limited introduction to using flight
plans. In addition, this section briefly covers the default navigation, map and frequency
pages available as part of the NAV page group. These pages will be used for most of your
in-flight navigation.
The Takeoff Tour assumes that the unit and antennas have been properly installed and
you have not changed any of the GNC 420’s default settings. If you have changed any
of the factory default settings (position format, units of measure, selectable fields, etc.),
the pictures shown here may not exactly match what you see on your GNC 420. Prior to
using your GNC 420 for the first time, we recommend that you taxi to a location that is
well away from buildings and other aircraft so the unit can collect satellite data without
interruption.
Powering up the GNC 420
The GNC 420’s power and COM volume are controlled using the
k
(power/ volume)
knob at the top left corner of the unit. Rotating it clockwise will turn unit power on
and increase the COM radio volume. After turning the unit on, a welcome page will be
displayed while the unit performs a self test.
The database confirmation page will appear next, which shows the current database
information on the NavData card (with the valid operating dates, cycle number and
database type indicated). The database is updated every 28 days, and must be current for
approved instrument approach operations. Information on database subscriptions is avail-
able inside your GNC 420 package.
To acknowledge the database information, press the
E
key.
The database confirmation page shows the
effective and expiration dates of the Jeppesen
database on the NavData Card.
The welcome page appears when the
GNC 420 is turned on. During the time this
screen is displayed, the GNC 420 performs a
self test to ensure proper operation.
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5
Enter the fuel capacity, fuel on board, or fuel
flow figures directly onto the appropriate field
of the instrument panel self-test page. These
figures will automatically be provided if your
installation includes connection to external
sensors.
TAKEOFF TOUR
Instrument Panel
Self Test
Once the database has been acknowledged, the instrument panel self-test page will
appear. Check for the following indications on other instruments:
• Course deviation - half left / no flag • Glidescope - half up / no flag
• TO/FROM flag - TO • Time to destination - 4 minutes
• Bearing to destination - 135° • Desired track - 149.5°
• Distance to dest. - 10.0 nautical mi. • Ground speed - 150 knots
• All external annunciators (if installed) - on
The instrument panel self-test page indicates the currently selected OBS course, fuel
capacity (CAP), fuel on board (FOB), and fuel flow (FF). The fuel capacity, fuel on board,
and fuel flow may be manually entered if your installation does not include connection to
sensors which automatically provide these figures.
To enter fuel capacity, fuel on board, or fuel flow figures (if not provided by sensors):
1. Rotate the large right knob (
h
) to select the “CAP”, “FOB”, or “FF” field.
2. Rotate the small (
f
) and large (
h
) right knobs to enter the desired figure, then press
E
.
Check CDI/HSI,
RMI and other
instruments
to verify these
indications.
Fuel Figures: May be
entered manually if
no sensor present.
Select to Set Fuel
Level to Full Capacity
Select to display
Checklists Page
Should match current OBS
course selection
{
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6
The instrument panel self-test page includes the selections to set fuel on board (FOB)
to full capacity and access the checklists page. This allows you to quickly set fuel to full
limits and display any checklists you’ve entered, such as start-up or take-off checklists.
To set fuel on board to full (if not provided by sensor):
1. Rotate the large right knob (
d
) to highlight “Set Full Fuel?”.
2. Press
E
and verify that fuel on board (FOB) now matches the fuel capacity (CAP) figure.
Fuel on board will now be reduced, over time, based on the fuel flow (FF) figure.
To view the checklists page:
1. Rotate the large right knob (
d
) to highlight “Go To Chklist?” and press
E
.
2. Rotate the large
(
d
) right knob to select the desired checklist, then follow the steps on page
133 to execute each step in the selected checklist.
3. Once you complete the desired checklist(s), press the small right knob (
a
) to return to the
checklists page. Press the small right knob (
a
) return to normal opera-tion on the satellite status
or map pages.
Once you’ve verified instrument operation with the instrument panel self-test page
displayed, rotate the large right knob (
d
) to highlight “OK” (if not already highlighted) ,
and press the Ekey.
The satellite status page will appear as the GNC 420 begins to collect satellite informa-
tion. An ‘Acquiring’ status message will be displayed on the satellite status page, and
the signal strength of any satellites received will appear as “bar graph” readings. This
is a good indication that you are receiving signals and a position fix will be determined.
Following the first-time use of your GNC 420, the time required for position fix will vary
- usually from one to two minutes.
Select “GoTo Chklist?” to display the checklist
page and any available checklists. The GNC
420 can hold up to nine checklists with up to
30 entries in each checklist.
Select “Set Full Fuel?” to set fuel on board
(FOB) to full capacity.
TAKEOFF TOUR
Fuel On Board
& Checklists
GNC 420 RevC prelim.indd 6 5/19/2003, 9:02:54 AM

7
If the unit can only obtain enough satellites for 2D navigation (no altitude), the unit
will use the altitude provided by your altitude encoder (if one is connected).
If the GNC 420 has not been operated for a period of six months or more, it may have
to ‘Search the Sky’ to collect new data. This means the unit is acquiring satellite data to
establish almanac and satellite orbit information, which can take 5 to 10 minutes. The sat-
ellite status page will display a ‘Search Sky’ status, and the message annunciator (MSG),
above the M key, will also flash to alert you of a system message, ‘Searching the Sky’.
To view a system message, press M.
Message Page
The message page will appear and display the status or warning information appli-
cable to the receiver’s current operating condition.
To return to the previous page after viewing a message, press
M
again.
The satellite status page shows the ID num-
bers for the satellites and the relative signal
strength of each satellite received (as a “bar
graph” reading.
‘Searching Sky’ indicates that satellite almanac
data is not available or has expired (if the
unit hasn’t been used for six months or more).
The data will be recollected from the first
available satellite.
The ‘INTEG’ annunciator (bottom left corner
of the screen) indicates that satellite coverage
is insufficient to pass built-in integrity moni-
toring tests. In the example above, not enough
satellites are being received to determine a
position.
TAKEOFF TOUR
Acquiring Satellites &
Viewing Messages
NOTE
The GNC 420 utilizes certain software algorithms to ensure reliable GPS
receiver operation. Receiver Autonomous Integrity Monitering or RAIM is an
example as is Fault Detection and Exclusion, or FDE. These features allow
navigation during Oceanic/Remote legs of a flight using the GNC 420. For fur-
ther details, please refer to pages 137, 149, and 167.
GNC 420 RevC prelim.indd 7 5/19/2003, 9:02:56 AM

8
TAKEOFF TOUR
Selecting COM
Frequencies
While the GNC 420 is acquiring a position, let’s take a minute to dial in the active
and standby frequencies you’ll be using for the first phase of your flight. The GNC 420’s
display is divided into separate ‘windows’ (or screen areas), including a COM window,
data field and the GPS window (the right 3/4 of the display).
To select the active frequency, you must first enter the frequency in the standby field,
and use the W key to move it to the active field.
To change the standby communication frequency:
1. Rotate the large left knob (
h
) to select the MHz, and the small left knob (
f
) to select the
kHz of the desired frequency.
2. Pr
ess the
W
key to place the standby communication frequency in the active field.
Once you’ve entered the active frequency, simply repeat step 1 above, to enter the
standby frequency.
Satellite status page with cursor in the COM
window.
To switch the active and standby frequencies,
press the Wkey. Switching the active and
standby frequencies will not remove the cur-
sor from the COM window.
COM Window
GPS Window
Active Frequency on top &
Standby on bottom
(highlighted by cursor)
{
{
User Selectable
Data field
}
Flight Phase
Indicator/Annunciator
{
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9
TAKEOFF TOUR
Map Page
The map page combines a moving map display
and navigation data for complete situational
awareness. Map setup pages are provided to
designate the maximum scale at which each
map feature will appear. These settings provide
an automatic decluttering of the map (based
upon your preferences) as you adjust the scale.
While viewing the map page, you can quickly
declutter and remove many of the background
map details by pressing the ckey (repeat-
edly) until the desired detail is depicted.
To change the map scale, press the or 
side of the Rkey.
After the GNC 420 acquires satellites and computes a position, the map page appears
automatically.
The map page displays your present position (using an airplane symbol) relative to
nearby airports, VORs, NDBs, intersections, user waypoints and airspace boundaries—
and your route is displayed as a solid line. Data fields for destination waypoint (WPT),
distance to waypoint (DIS), desired track (DTK) and ground speed (GS) appear on the
right hand side of the display.
These fields are user selectable (see page 38 for more information) to allow you to
configure the unit to your own preferences. Available settings include: altitude, bearing,
enroute safe altitude, estimated time of arrival, minimum safe altitude, and ground track.
See Section 9 for definitions of these navigation terms.
Data
Fields
Present
Position
Map Display
Map Scale
Map Page
Desired Track
GNC 420 RevC prelim.indd 9 5/19/2003, 9:02:58 AM

10
*Seven NAV Pages are available when the
GNC 420 installation includes connection to
traffic and/or weather information sources.
See 400 Series Pilot’s Guide Addendum, part
number 190-00140-10.
The map page is one of six pages available under the NAV group:
• Default NAV page • Map page
• NAVCOM page • Position page
• Satellite status page • Vertical navigation page
To select the desired NAV page, rotate the small right knob (
a
) until the desired page
is displayed.
If you are currently viewing a page which is not part of the NAV group, you can
quickly return to the NAV group using the
c
key.
To select the NAV group and display the default NAV page, press and hold
c
.
MAIN PAGE GROUPS
In addition to the NAV group of pages, additional groups of pages are available for
waypoint information (WPT) and auxiliary (AUX) functions such as flight planning or unit
settings.
To select the desired page group, rotate the large right knob (
d
) until a page from the
desired group is displayed.
To select the desired page within the group, rotate the small right knob (
a
) until the
desired page is displayed.
6 available
pages (see
list above)
The bottom right corner of the screen indi-
cates which page group is currently being
displayed (e.g., NAV or WPT), the number of
screens available within that group (indicated
by square icons) and the placement of the cur-
rent screen within that group (indicated by a
highlighted square icon). To select a different
page within the group, rotate the small right
knob (a).
TAKEOFF TOUR
NAV Pages &
Page Groups
NAV
10 available
pages (see
list on pg. 86)
4 available
pages (see list
on pg. 123)
AUXWPT
GNC 420 RevC prelim.indd 10 5/19/2003, 9:02:59 AM

11
TAKEOFF TOUR
Page Groups
(Large right knob to change page groups)
a
(Small right knob to select pages within the group)
Selection of any main page is performed using the large (d)and small (a)right knobs. The large right knob (d)selects the
page group: NAV, WPT, AUX, or NRST. The small right knob (a)selects the desired page within a group. To quickly select the
default NAV page, press and hold c.
d
Default NAV Map NAVCOM Position Satellite Status VNAV
NAV Group
Flight Planning Utility Setup 1 Setup 2
AUX Group
WPT Group
Airport Location Airport Runway Airport Frequency Airport Approach Airport Arrival Airport Departure Intersection NDB VOR User Waypoint
Nearest Airport Nearest
Intersection
Nearest NDB Nearest VOR Nearest User Nearest Center Nearest Flight
Service
Nearest Airspace
NRST Group
GNC 420 RevC prelim.indd 11 5/19/2003, 9:03:00 AM

12
The GNC 420 can use direct point-to-point navigation to guide you from takeoff to
touchdown, even in the IFR environment. Once a destination is selected, the unit will
provide speed, course and distance data based upon a direct course from your pres-
ent position to your destination. A destination can be selected from any page with the
D(direct-to) key.
To select a direct-to destination:
1. Press the
D
key. The select direct-to waypoint page will appear with the destination field
highlighted.
2. Rotate the small right knob (
a
) to enter the first letter of the destination waypoint identifier.
The destination waypoint may be an airport, VOR, NDB, intersection or user waypoint, as long
as it is in the database or stored in memory as a user waypoint.
3. Rotate the large right knob (
d
) to the right to move the cursor to the next character position.
4. Repeat steps 2 and 3 to spell out the rest of the waypoint identifier.
5. Press
E
to confirm the identifier. The “Activate?” function field will be highlighted.
6. Press
E
to activate a direct-to course to the selected destination.
Confirm the selected direct-to destination by
highlighting “Activate?” and pressing E.
TAKEOFF TOUR
Direct-To Navigation
“Activate?”
Function Field
Select Direct-To Waypoint Page
Destination
Waypoint
Identifier Field
Once a direct-to destination is selected, press
and hold cto display the default NAV
page.
GNC 420 RevC prelim.indd 12 5/19/2003, 9:03:04 AM