GARMIN GNC 420 User Guide

GNC 420

Pilots Guide and Reference

This manual is written for Main System Software version 2.08 or above, and is not suit­able for earlier software versions.

INTRODUCTION

GARMIN International, Inc., 1200 East 151st Street, Olathe, Kansas 66062 USA
Tel: [phone] Fax: [phone]

GARMIN (Europe) LTD, Unit 5, The Quadrangle, Abbey Park, Romsey, Hampshire S051 9AQ, UK
Tel: [phone] Fax: [phone]

GARMIN (Asia) Corp., 3F, No. 1, Lane 45, Pao Hsing Road, Hsin Tien, Taipei, Taiwan R.O.C.
Tel: [phone]-4107 Fax: [phone]-1758

Web Site Address: www.garmin.com

GARMIN, GNC 420, Spell’N’Find, AutoLocate,
PhaseTrac12 and AutoStore are trademarks of
GARMIN and may only be used with permission.

© 1999 GARMIN Corporation. All rights reserved. Except as expressly provided herein,
no part of this manual may be reproduced, copied, transmitted, disseminated, down­loaded or stored in any storage medium, for any purpose without the express prior writ-

NavData® is a registered trademark of Jeppesen,
Inc.

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 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.

Foreword

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

i

INTRODUCTION

PROCEDURES

5

Approach Examples

Cautions

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

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.
Furthermore, there is no guarantee that interfer­ence will not occur in a particular installation.

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

If this equipment does cause harmful interfer­ence, the user is encouraged to try to correct the
interference by relocating the equipment or connect­ing 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 follow­ing conditions: (1) This device may not cause harm­ful 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.

ii

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.

Accessories & Packing List

INTRODUCTION

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.

Accessories and

Packing List

To obtain accessories for your GNC 420,
please contact your GARMIN dealer.

iii

INTRODUCTION

5

PROCEDURES

Warranty

Approach Examples

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 cus­tomer is, however, responsible for any transportation costs. This warranty does not
cover failures due to abuse, misuse, accident or unauthorized alteration or repairs.

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]

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 num­ber clearly marked on the outside of the pack­age, 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.

iv

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, STATU­TORY 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.

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 Dkey

Section 4: Flight Plans (

Creating and using flight plans
Retrieving and editing stored flight plans

key and FPL page group) . . . . . . . . . . . . . . . . . . .52

F

INTRODUCTION

Table of Contents

CONVENTIONS USED IN THIS MANUAL

A circled number (e.g.,”
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”).



”) will appear next



Section 5: Approaches, Departures and Arrivals (

key) . . . . . . . . . . . . . . . .64

P

Selecting and flying non-precision/precision approaches
Selecting and using departures (SIDs) and arrivals (STARs)

A highlighted “NOTE” area appears on many
pages to point out additional information or
items of particular importance related to a
given subject.

v

INTRODUCTION

5

PROCEDURES

Approach Examples

Table of Contents

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

To quickly and easily locate information
on specific tasks, please refer to the Index
on page 169.

vi

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

Key and Knob Functions

G

COM

PWR

PUSH

VOLSQ/

C

GARMIN

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

k

A

f

W

radio volume. Press momentarily to disable automatic squelch control.

The large left knob is used to tune the megahertz (MHz) value of the
standby frequency for the communications transceiver.

The small left knob is used to tune the kilohertz (kHz) value of the stand­by frequency 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).

TAKEOFF TOUR

Key and Knob

Functions

Left-hand Keys and Knobs

Right-hand K

R

D

eys 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 destination. See Section 3.

Right-hand Keys and Knobs

1

TAKEOFF TOUR

PROCEDURES

5

Key and Knob
Approach Examples

Functions

m

c

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.

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.

E

d

a

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.

2

Bottom Row Keys

The NRST key displays the nearest airports page. Then, rotating the small

N

O

M

F

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 mes­sages 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 infor­mation on flight plans.

TAKEOFF TOUR

Key and Knob

Functions

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 (
vate the cursor and rotate the large right knob

) to scroll through the list.

(

d

) to acti-

a

}

scroll bar

P

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.

3

TAKEOFF TOUR

5

PROCEDURES

Approach Examples

Power On

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.

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—including 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
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.

k

(power/

During the self-test, check for the following indications on other instruments:

• Course deviation - half left / no flag • Ground speed - 150 knots

• TO/FROM flag - TO • Time to destination - 4 minutes

• Bearing to destination - 135° • Desired track - 149.5°

The database confirmation page shows the
effective and expiration dates of the Jeppesen

4

database on the NavData Card.

• Distance to dest. - 10.0 nautical mi.

• All external annunciators (if installed) - on

The land data page will appear next, followed by the database confirmation page,

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 available inside your GNC 420 package.

To acknowledge the database information, press the Ekey.

Once the database has been acknowledged, the satellite status page will appear,

and the GNC 420 will begin to collect satellite information. An ‘Acquiring’ status 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 a position fix will vary—usually from one to
two minutes.

TAKEOFF TOUR

Acquiring Satellites &

Viewing Messages

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 satellite status page will display a ‘Search Sky’ status, and the
message annunciator (MSG), above the

key, will also flash to alert you of a sys-

M

tem message, ‘Searching the Sky’.

To view a system message, press

M

.

The message page will appear and display the status or warning information
applicable 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 num­bers for the satellites and the relative signal
strength of each satellite received (as a “bar
graph” reading.

‘Search 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 moni­toring tests. In the example above, not enough
satellites are being received to determine a
position.

5

TAKEOFF TOUR

PROCEDURES

5

Selecting COM

Approach Examples

Frequencies

Satellite status page with cursor in the COM
window.

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).

Active Frequency on top &

Standby on bottom

(highlighted by cursor)

COM Window

User Selectable

Data field

To select the active frequency, you must first enter the frequency in the standby
field, and use the Wkey 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.

GPS Window

}

ress the

2. P

active field

Once you’ve entered the active frequency, simply repeat step 1 above, to enter
the standby frequency.

To switch the active and standby frequencies,
press the
standby frequencies will not remove the cur­sor from the COM window.

6

key. Switching the active and

W

key to

W

.

place the standby communication frequency in the

After the GNC 420 acquires satellites and computes a position, the map page

will appear automatically.

TAKEOFF TOUR

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.

Data

Map Display

Map Scale

Map Page

Fields

Present

Position

Desired Track

These fields are user selectable (see page 36 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.

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
edly) until the desired detail is depicted.

c

key (repeat-

To change the map scale, press the
side of the

R

key.

V or ^

7

TAKEOFF TOUR

PROCEDURES

5

NAV Pages &

Approach Examples

Page Groups

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 ckey.

To select the NAV group and display the default NAV page, press and hold c.

MAIN PAGE GROUPS

The bottom right corner of the screen indi­cates 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 cur­rent screen within that group (indicated by a
highlighted square icon). To select a different
page within the group, rotate the small right

a

).

knob (

8

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 (
the desired page is displayed.

NAV

6 available
pages (see

list above)

10 available

pages (see

list on pg. 84)

AUXWPT

4 available

pages (see list

on pg. 121)

a

) until

a

(Small right knob to select pages within the group)

NAV Group

TAKEOFF TOUR

Page Groups

Default NAV

Map

NAVCOM

Position

WPT Group

d

Airport Location

Airport Runway

Airport Frequency

Airport Approach

AUX Group

(Large right knob to change page groups)

Flight Planning

Utility

Selection of any main page is performed using the large (
page group: NAV, WPT, or AUX. The small right knob (
NAV page, press and hold

c

.

Setup 1

Setup 2

Satellite Status

Airport Arrival

) and small (a) right knobs. The large right knob (d) selects the

d

) selects the desired page within a group. To quickly select the default

a

VNAV

Airport Departure

Intersection

NDB

VOR

User Waypoint

9

TAKEOFF TOUR

5

PROCEDURES

Approach Examples

Direct-To Navigation

Destination

Waypoint

Identifier Field

Select Direct-To Waypoint Page

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 present position to your destination. A destination can be selected from any
page with the D(direct-to) key.

“Activate?”

Function Field

10

Confirm the selected direct-to destination by
highlighting “Activate?” and pressing

Once a direct-to destination is selected, press
and hold
page.

to display the default NAV

c

E

.

To select a direct-to destination:

1. Press the Dkey. The select direct-to waypoint page will appear with the destination
field highlighted.

2. Rotate the small right knob (
tifier. 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 (
position.

4. Repeat steps 2 and 3 to spell out the rest of the waypoint identifier.

5. Press

6. Press

to confirm the identifier. The Activate? function field will be highlighted.

E

to activate a direct-to course to the selected destination.

E

a

d

) to enter the first letter of the destination waypoint iden-

) to the right to move the cursor to the next character

Course Deviation Indicator (CDI)

TAKEOFF TOUR

Active Leg of

Flight Plan

Default NAV Page

User-

selectable

Data Fields

During most flights, the default NAV, map and NAVCOM pages will be the pri-

mary pages used for navigation. The default NAV page displays a graphic course
deviation indicator (CDI), the active leg of your flight plan (as defined by the cur­rent “from” and “to” waypoints), and six user-selectable data fields. The default set­tings for these fields are distance to waypoint (DIS), desired track (DTK), bearing to
waypoint (BRG), ground speed (GS), ground track (TRK) and estimated time en
route (ETE). See Section 9 for definitions of these navigation terms. The default
NAV page is selected using the steps described on page 8.

From the default NAV page, simply rotate the small right knob (

) to display the

a

The data fields on the default NAV page may
be custom-tailored to your preferences. A menu
selection is provided to “Change Fields?”

map page (see page 7) and again to display the NAVCOM page. The NAVCOM page

displays the available frequencies (communications and navigation) for the departure
airport, any en route airports which are included in your flight plan, and the final
destination airport. When using the direct-to function, frequencies will be listed for
the airport nearest to your starting position and the destination airport.

Default NAV Page

To display the frequency list for the desired flight plan or direct-to airport:

1. Push the small right knob (r) to activate the cursor on the airport identifier field (in the
GPS window).

{continued}

The large right knob (
data field you wish to change. Then use the
small right knob (
options and select the desired data item.

) is used to select the

d

) to display a list of data

a

11

PROCEDURES

TAKEOFF TOUR

5

Approach Examples

NAVCOM Page

2. Rotate the small right knob (a) to display the list of airports (departure, arrival and en
route) for your flight plan or direct-to. Continue to rotate the small right knob (
the desired airport is selected.

3. Press

to display the frequency list for the selected airport.

E

a

) until

The navigation/communications (NAVCOM)
page provides a complete list of airport fre­quencies at your departure, en route and
arrival airports. To place a frequency from this
list on standby, highlight the desired frequen­cy and press

To display frequencies for a different airport
along your flight plan, press the small right
knob (
field. Rotate the small right knob (
play the list of airports within your flight plan.
Continue rotating the small right knob (
select the desired airport and press

) to highlight the airport identifier

r

E

.

) to dis-

a

) to

a

.

E

Arrival,

Enroute or

Departure Airport

NAVCOM Page

A frequency listed on the NAVCOM page can be quickly transferred to the

standby field of the COM window. (NAV frequencies are shown for reference only.)
This time saving process prevents having to “re-enter” a frequency already dis­played elsewhere on the screen.

To select a communication frequency:

1. Push the small right knob (r) to activate the cursor in the GPS window.

2. Rotate the large right knob (

3. Press
COM frequencies will automatically go to the standby field of the COM tranceiver.

4. To activate the selected frequency, press the

to transfer the selected frequency to the standby field in the COM window.

E

) to select the desired frequency from the list.

d

key

W

Frequency

List

12

.

Once the direct-to or flight plan is confirmed, the whole range of instrument
procedures is available to you. Departures (SIDs), arrivals (STARs), non-precision
and precision approaches are stored within the NavData card and available using
the

(procedures) key.

P

TAKEOFF TOUR

IFR Procedures

To display the procedures page, press

The steps required to select and activate an approach, departure or arrival are
identical. In this introductory section, we’ll show examples of the steps required to
select an approach, but keep in mind the same process also applies to departures
and arrivals.

To select an approach, departure or arrival:

1. Rotate the small right knob (a) to select the desired option (Select Approach?,
Select Arrival? or Select Departure?) from the procedures page.

2. Press
approaches or STARs) or departure (when using SIDs) airport.

3. Rotate the small right knob (

4. For approaches, a window appears to select the desired initial approach fix (IAF) or pro­vide a vectors option to select just the final course segment of the approach. Rotate the
small right knob (
extends the final inbound course beyond the final approach fix, allowing you to intercept
the final course segment beyond its normal limits.)

5. For departures and arrivals, a window appears to select the desired transition. Rotate the
small right knob (

In your flight plan or direct-to, the departure or arrival airport is replaced with

the sequence of waypoints contained within the selected procedure.

to display a list of available procedures for the arrival (when using

E

a

) to select the desired option and press E. (The vectors option

a

) to select the desired option and press E.

a

.

P

) to select the desired procedure and press E.

Press the
page. Rotate the large right knob (
select the desired option.

A window will appear to select the desired
procedure. Use the large right knob (
make your selection.

key to display the procedures

P

d

) to

d

) to

13

TAKEOFF TOUR

PROCEDURES

5

Nearest Airport

Approach Examples

Emergency Search

The NRST page group provides detailed information on the nine nearest air­ports, VORs, NDBs, intersections and user-created waypoints within 200 nm of
your current position. In addition, pages are also provided to display the five near­est center (ARTCC/FIR) and Flight Service Station (FSS) points of communication,
plus alert you to any special-use (SUA) or controlled airspace you may be in or near.

To display the NRST pages:

1.

Press the

(

) key. The nearest airport page will appear.

N

14

To display a list of nearby airports, press the

(

)

key to select the nearest airport page.

N

To scroll through the list, press the small right
knob (

), then rotate the large right knob (d).

a

2. Rotate the small right knob (

The nearest airport page (shown at left) is one of eight pages available under the
NRST group:

• Nearest airport page • Nearest intersections page

• Nearest NDB page • Nearest VOR page

• Nearest user waypoints page • Nearest ARTCC page

• Nearest FSS page • Nearest airspace page

You may examine both the communication frequencies and runway information
directly from the nearest airport page. As discussed earlier for the NAVCOM page
(see page 12), you may also place any displayed frequency into the standby COM
field by highlighting the frequency with the cursor and pressing

) to select the desired NRST page.

a

E

.

To view additional information for a nearby airport:

1. Press the small right knob (r) to activate the cursor.

2. Rotate the large right knob (

3. Press

to display waypoint (WPT) information pages for the selected airport.

E

) to select the desired airport from the list.

d

TAKEOFF TOUR

Nearest Airports:

Additional Information

4. To display runway and frequency information, press (
rotate the small right knob (

The nearest airport page may be used in conjunction with the direct-to (D)

key to quickly set a course to a nearby facility in an in-flight emergency. Selecting a
nearby airport as a direct-to destination will override your flight plan or cancel a
previously selected direct-to destination. (You’ll still have the option of returning to
your flight plan by cancelling the direct-to. See page 51.)

To select a nearby airport as a direct-to destination:

From the nearest airport page...

1. Press the small right knob (

2. Rotate the large right knob (

3. Press

From an airport information page...

1. Press

D, E

D, E

and E(again) to navigate to the nearby airport.

and E(again) to navigate to the nearby airport.

) to display the desired information page.

a

) to activate the cursor.

r

) to select the desired airport from the list.

d

) to remove the cursor and

r

Additional information for a nearby airport is
available by highlighting an identifier on the
list and pressing

To select a nearby airport as a new destina­tion, highlight its identifier, press
and

E

(again).

E

.

D, E

15

TAKEOFF TOUR

PROCEDURES

5

Special-use and

Approach Examples

Controlled Airspace

When an airspace alert occurs, the message
(MSG) annunciator will flash. Press
view the alert message.

M

The last page in the NRST group, the nearest airspace page, provides informa-

tion for up to nine controlled or special-use airspaces near or in your flight path.
Airspace information appears on this page based upon the same criteria used for air­space alert messages. Nearby airspace information and airspace alert messages are
provided according to the following conditions:

• If your projected course will take you inside an airspace within the

next ten minutes, the message “Airspace ahead -- less than 10
minutes” will appear.

• If you are within two nautical mile of an airspace and your current

course will take you inside, the message “Airspace near and ahead”
will appear.

• If you are within two nautical miles of an airspace and your current

course will not take you inside, the message “Near airspace less than
2nm” will appear.

• If you have entered an airspace, the message “Inside airspace” will

appear.

to

By default, airspace alert messages are turned off. When turned on, the message
(MSG) annunciator located directly above the
airspace message. (See page 138 for information on enabling airspace alert messages.)

To view an airspace alert message:

key will flash to alert you to the

M

16

To view additional information about the air­space, select the nearest airspace page.
Detailed information is available by highlight­ing the airspace name and pressing

E

.

1. Press the

2. Press

M

Note that the airspace alerts are based upon three-dimensional data (latitude,
longitude and altitude) to avoid nuisance alerts. The alert boundaries for controlled
airspace are also sectorized to provide complete information on any nearby airspace.
Additional information about a nearby airspace—such as controlling agency, fre­quency and floor/ceiling limits—is available from the nearest airspace page (see
page 117 and illustrations shown at left).

key. The message page appears with the alert message.

M

again to return to the previous display.

The GNC 420 lets you create up to 20 flight plans, with up to thirty-one way-

points in each flight plan. Flight plans are created, edited and activated using the

key. The FPL page group includes two pages: the active flight plan page and

F

the flight plan catalog. The active flight plan page provides information and editing
features for the flight plan currently in use (referred to as “flight plan 00”). The
flight plan catalog serves as the main page for creating new flight plans, as well as
editing or activating previously created flight plans.

Since using flight plans is arguably one of the more complex features of the
GNC 420, we’ll only discuss it briefly here—focusing on creating a new flight plan
and activating it to use for navigation. After reading through this brief introduction,
answers to additional questions you may have about flight plans can be found in the
reference section, starting on page 52.

To create a new flight plan:

TAKEOFF TOUR

Flight Plans

1.

Press the

2. Press the mkey to display the flight plan catalog options.

3. Rotate the large right knob (

4. The cursor will appear on the first waypoint identifier field (located directly below WAY­POINT). Use the large (
waypoint in the flight plan. (The small knob is used to select the desired letter or number
and the large knob is used to move to the next character space.)

5. Press

6. Repeat steps 4 and 5, above, until all waypoints for the flight plan have been entered.

E

blank waypoint identifier field.

key and rotate the small right knob

F

) to select Create New Flight Plan? and press E.

d

) and small (a) right knobs to enter the identifier of the first

d

once the identifier has been selected. The cursor will move to the next

(a)

to select the flight plan catalog.

Active flight plan page with flight plan
currently in use.

To create a new flight plan, select “Create
New Flight Plan?” from the flight plan catalog
options.

17

TAKEOFF TOUR

PROCEDURES

Flight Plans and

5

Approach Examples

Additional Reading

Once the flight plan is created, it may be activated from an options window.
Activating the flight plan will place it into “flight plan 00” (a copy of it will still
reside in the original catalog location) and replaces any flight plan which currently
exists in “flight plan 00.”

To activate the new flight plan:

1. Press the mkey to display the flight plan catalog options.

2. Rotate the small right knob (a) to select Activate Flight Plan? and press E.

This Takeoff Tour is intended to provide a brief introduction of the GNC 420’s
major features. The Reference section of this manual describes these features, and
others, in additional detail. Use the reference section, as needed, to learn or review
the details regarding a particular feature. The Index (beginning on page 169) may
be used to quickly locate the information you want within the reference section.

18

Enter the identifier for each airport and/or
navaid into the flight plan in the same
sequence you wish to fly.

Select “Activate Flight Plan?” from the page
menu to begin using the new flight plan.

Now that you’re familiar with the basics, some suggested reading within the
Reference section includes:

• Flight plan features - see page 52

• Waypoint information pages (database information) - see page 84

• IFR procedures - see page 64

• Unit settings (configuring the unit to your preferences) - see page 121

If you’re unable to locate the information you need, we’re here to help!
GARMIN’s Customer Service staff is available during normal business hours (U.S.
Central time zone) at the phone and fax numbers listed on page iv. You can also
reach us by mail (see page iv) or at our web site address: www.garmin.com.

Section 1

COM

Communicating with the GNC 420

The GNC 420 features a digitally-tuned VHF COM radio that provides a seam­less transition from communication to navigation, bringing the two most important
functions in flying together in one panel-mounted unit. The GNC 420’s COM radio
operates in the aviation voice band, from 118.000 to 136.975 MHz, in 25 kHz steps
(default). For European operations, a COM radio configuration to allow for 8.33
kHz steps is also provided (see pages 144-145).

Volume

COM radio volume is adjusted using thekknob. Rotate thekknob clock­wise to increase volume, or counterclockwise to decrease volume.

Squelch

The COM radio features an automatic squelch, providing maximum sensitivity
to weaker signals while rejecting many localized noise sources. You may wish to
override this automatic squelch function when listening to a distant station or when
setting the desired volume level. Thekknob allows you to disable the automatic
squelch and keep the COM audio open continuously.

To override the automatic squelch, press thekknob momentarily. Press
again to return to automatic squelch operation.

k

Radio Volume

Auto Squelch

Press thekknob momentarily to override
the automatic squelch. Note the “RX” receive
indication when receiving a station.

1

“TX” appears at the upper right corner of the
screen while transmitting.

19

COM

PROCEDURES

5

1

Tuning cursor in the COM window. Use the
small (
the desired standby frequency.

Tuning Cursor

Approach Examples

Active/Standby Freqs

) and large (h) left knobs to dial in

f

COM Window and Tuning

Communication frequencies are selected with the tuning cursor in the standby

COM frequency field, and using the small (
the desired frequency. The standby frequency always appears below the active fre­quency. The active frequency is the frequency currently in use for transmit and
receive operations.

A frequency may also be quickly selected from the database by simply highlight-

ing the desired frequency on any of the main pages and pressing the
process is referred to as auto-tuning. Once a frequency is selected in the standby
field, it may be transferred to the active frequency by pressing the

While receiving a station, an “RX” indication appears in the upper right corner
of the COM window—to the immediate right of “COM”. A “TX” indication
appears at this location while you are transmitting.

Except for the Emergency Channel function, (see page 24)
the active frequency cannot be accessed directly—only the
standby frequency will be highlighted by the tuning cursor.

) and large (h) left knobs to dial in

f

key. This

E

key.

W

NOTE

20

Once the standby frequency is selected, use

(flip-flop) key to make the frequency

the

W

active for transmit and receive operations.

To select a COM frequency:

1. Rotate the large left knob (h) to select the desired megahertz (MHz) value. For exam­ple, the 118 portion of the frequency 118.300.

2. Rotate the small left knob (f) to select the desired kilohertz (kHz) value. For example,
the .300 portion of the frequency 118.300.

To make the standby frequency the active frequency, press the W(flip flop) key.

Auto-Tuning

The GNC 420’s auto-tune feature allows you to quickly select any database fre­quency in the GPS window as your standby frequency. Any COM frequency dis­played in the GPS window can be transferred to the standby COM frequency field,
with a minimum of keystrokes required. The following are some examples of select­ing COM frequencies from some of the main GPS pages.

To select a COM frequency for a nearby airport:

1. Select the nearest airport page from the NRST page group. (See page 109.) Press and
hold

, to display the nearest airport page.

N

COM

Auto-Tuning from

Nearest Airport Page

1

2. Press the small right knob (
field of the first airport in the list. If you wish to select another airport, rotate the large right
knob (

3. The nearest airport page displays the common traffic advisory frequency (CTAF) for each
listed airport. To select this frequency, rotate the large right knob (
desired airports CTAF frequency and press
field of the COM window.

4. To display the entire list of frequencies for a nearby airport and select from that list, start
with the desired airport highlighted on the nearest airport page (as described in step 3
above), then press
cursor and rotate the small right knob (
right knob (
to highlight the desired frequency. Press
standby COM window field.

) to highlight the desired airport.

d

E

) momentarily to reactivate the cursor and rotate the large right knob (

r

) momentarily to place the cursor on the airport identifier

r

) to highlight the

to place the frequency in the standby

E

. Now press the small right knob (r) momentarily to remove the

) to display the frequency list. Press the small

a

to place the highlighted frequency in the

E

d

d

)

Nearest airport page with common traffic
advisory frequency (CTAF) for the closest
airport highlighted.

From the nearest airport page, select the
desired airport to show a more detailed listing
of frequencies for that airport.

21

5

1

COM

PROCEDURES

Auto-Tuning FSS

Approach Examples

or Center

To select a COM frequency for a nearby flight service station (FSS):

1. Select the nearest flight service page from the NRST page group. (See page 109, or
rotate the large right knob,
the small right knob,

2. Press the small right knob (

a

, until the NRST pages appear. Then, if necessary, rotate

d

, to display the desired NRST page.)

) momentarily to place the cursor on the page.

r

22

Use the nearest FSS page to retrieve the fre­quency(s) for the nearest flight service station
(FSS.)

Use the nearest ARTCC page to quickly
retrieve the frequency(s) for the nearest center
(ARTCC) facility.

3. Rotate the large right knob (
the frequency in the standby field of the COM window.

To select a COM frequency for a nearby air route traffic control center

(ARTCC):

1. Select the nearest center page from the NRST page group. (See page 109, or rotate the
large right knob,
right knob,

2. Press the small right knob (

3. Rotate the large right knob (
place the frequency in the standby field of the COM window.

a

, until the NRST pages appear. Then, if necessary, rotate the small

d

, to display the desired NRST page.)

) to highlight the FSS frequency and press Eto place

d

) momentarily to place the cursor on the page.

r

) to highlight the ARTCC frequency and press Eto

d