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G N C 4 2 0
P i l o t s G u i d e a n d R e f e r e n c e
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This manual is written for Main System Software version 2.08 or above, and is not suit-
able for earlier software versions.
GARMIN International, Inc., 1200 East 151st Street, Olathe, Kansas 66062 USA
Tel: 913-397-8200
Fax: 913-397-8282
GARMIN (Europe) LTD, Unit 5, The Quadrangle, Abbey Park, Romsey, Hampshire S051 9AQ, UK
Tel: 011-44-1794-519944
Fax: 011-44-1794-519222
GARMIN (Asia) Corp., 3F, No. 1, Lane 45, Pao Hsing Road, Hsin Tien, Taipei, Taiwan R.O.C.
Tel: 011-886-02-2917-4107
Fax: 011-886-02-2917-1758
Web Site Address: www.garmin.com
© 1999 GARMIN Corporation. All rights reserved. Except as expressly provided herein,
no part of this manual may be reproduced, copied, transmitted, disseminated, down-
loaded or stored in any storage medium, for any purpose without the express prior writ-
ten consent of GARMIN Corporation. GARMIN Corporation 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 man-
ual 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.
July 1999
190-00140-20 Rev. A
INTRODUCTION
Foreword
GARMIN, GNC 420, Spell’N’Find, AutoLocate,
PhaseTrac12 and AutoStore are trademarks of
GARMIN and may only be used with permission.
NavData® is a registered trademark of Jeppesen,
Inc.
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5
PROCEDURES
INTRODUCTION
Approach Examples
Cautions
NOTE: This device complies with Part 15 of the
FCC limits for Class B digital devices. This equip-
ment generates, uses, and can radiate radio fre-
quency energy and, if not installed and used in
accordance with the instructions, may cause harm-
ful interference to radio communications.
Furthermore, there is no guarantee that interfer-
ence 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 connect-
ing 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.
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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,
carefully 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 Availability (SA) program. With “SA” on, GPS altitude may be in error by
several hundred feet. Never use GPS altitude for vertical navigation.
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.
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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
package includes the following items. If any parts are missing or damaged, please
see your GARMIN dealer immediately.
Standard Package:
• GNC 420 Unit & NavData® Card
• GPS Antenna
• Installation Rack & Connectors
• Pilot’s Guide & Quick Reference Guide
• Database Subscription Packet
• Warranty Registration Card
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 correct 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.
INTRODUCTION
Accessories and
Packing List
To obtain accessories for your GNC 420,
please contact your GARMIN dealer.
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5INTRODUCTION
PROCEDURES
Approach Examples
Warranty
GARMIN is fully committed to your satisfac-
tion 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
(913) 397-8200
FAX (913) 397-8282
To obtain warranty service, call the GARMIN
Customer Service department for a returned
merchandise tracking number. The unit should
be securely packaged with the tracking num-
ber clearly marked on the outside of the pack-
age, and sent freight prepaid and insured to a
GARMIN warranty service station. A copy of
the original sales receipt is required as proof
of purchase for warranty repairs. 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.
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GARMIN Corporation warrants this product to be free from defects in materials
and workmanship for one year from the date of purchase. GARMIN will, at its sole
option, repair or replace any components that fail in normal use. Such repairs or
replacement will be made at no charge to the customer for parts or labor. The cus-
tomer is, however, 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
EXCLUSIVE, AND IN LIEU OF ALL OTHER WARRANTIES EXPRESSED OR
IMPLIED, INCLUDING ANY LIABILITY ARISING UNDER WARRANTY OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, STATU-
TORY OR OTHERWISE. THIS WARRANTY GIVES YOU SPECIFIC LEGAL
RIGHTS, WHICH MAY VARY FROM STATE TO STATE.
IN NO EVENT SHALL GARMIN BE LIABLE FOR ANY INCIDENTAL,
SPECIAL, 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.
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PART ONE: INTRODUCTION
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .i
Cautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ii
Accessories/Packing List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iii
Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iv
Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .v-vi
Takeoff Tour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-18
PART TWO: REFERENCE
Section 1: Communicating with the GNC 420 . . . . . . . . . . . . . . . . . . . . . . . . . .19
COM frequencies
Active and standby frequencies
Section 2: NAV Page Group (GPS navigation) . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Using page groups and selecting the desired page
Using the default NAV and map pages
Section 3: Direct-to Navigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47
Using the D key
Section 4: Flight Plans (F key and FPL page group) . . . . . . . . . . . . . . . . . . .52
Creating and using flight plans
Retrieving and editing stored flight plans
Section 5: Approaches, Departures and Arrivals (P key) . . . . . . . . . . . . . . . .64
Selecting and flying non-precision/precision approaches
Selecting and using departures (SIDs) and arrivals (STARs)
INTRODUCTION
Table of Contents
CONVENTIONS USED IN THIS MANUAL
A circled number (e.g.,””) 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 step#3
options). This same convention is used when
multiple procedures are listed on the same
page and illustrations are provided for the
steps described in one or both procedures
(e.g.,”a” and ”b”).
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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5INTRODUCTION
PROCEDURES
Approach Examples
Table of Contents
To quickly and easily locate information
on specific tasks, please refer to the Index
on page 169.
vi
Section 6: WPT Page Group (Waypoint/database information) . . . . . . . . . . . . . .84
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.) . . . . . . . . . . . . . . . . . . . . 109
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) . . . . . . . . . . . .121
Section 9: Messages, Abbreviations & Navigation Terminology . . . . . . . . . . . .146
Appendix A: NavData® Card Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .159
Appendix B: Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .160
Appendix C: Map Datums . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .161
Appendix D: Troubleshooting Q & A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .163
Appendix E: Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .169