Garmin Gnc 250Xl Users Manual 2

2015-02-28

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250xl manual 2

7/17/98 1:26 PM

Page i

G N C 2 5 0 X L

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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Page ii

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Page i

INTRODUCTION
Foreword

Software Version 2.01 or above

© 1997 GARMIN Corporation
1200 East 151st Street, Olathe, Kansas 66062-3426, USA
GARMIN (Europe) LTD, Unit 5, The Quadrangle, Abbey Park Industrial Estate,
Romsey S051 9AQ, UK
Web Site Address: www.garmin.com
All rights reserved. No part of this manual may be reproduced or transmitted in any
form or by any means, electronic or mechanical, including photocopying and recording, for any purpose without the express written permission of GARMIN.

GARMIN, GNC 250XL, Spell’N’Find, AutoLocate,
PhaseTrac12, GPSCOM and AutoStore are
trademarks of GARMIN and may only be used
with permission.
NavData® is a registered trademark of
Jeppesen, Inc.
All rights reserved.

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.

March 1997

190-00067-60 Rev. A

Printed in USA
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Page ii

INTRODUCTION
Cautions

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.
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 250XL 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

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 250XL is a precision electronic NAVigation AID
(NAVAID), any NAVAID can be misused or misinterpreted and therefore become
unsafe.
Use the GNC 250XL at your own risk. To reduce the risk of unsafe operation,
carefully review and understand all aspects of this Owner’s Manual and thoroughly
practice using the simulator mode prior to actual use. When in actual use, carefully
compare indications from the GNC 250XL 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 250XL is geometric height above mean sea
level and could vary significantly from altitude displayed by pressure altimeters in aircraft. Never use GPS altitude for vertical navigation.
The Jeppesen database incorporated in the GNC 250XL 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 250XL package.
Pilots using an out-of-date database do so entirely at their own risk.

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Page iii

Accessories & Packing List
Congratulations on choosing the finest, most advanced panel mount VFR
GPSCOM available. The GNC 250XL represents GARMIN’s commitment to provide
an accurate, easy-to-use GPS for all of your aviation needs.

INTRODUCTION
Accessories and
Packing List

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 250XL Unit & NavData® Card
GPS Antenna
Installation Rack & Connectors
Pilot’s Guide & Quick Reference Guide
Database Subscription Packet
Warranty Registration Card

To obtain accessories for your GNC 250XL,
please contact your nearest GARMIN dealer.

Optional Accessories:
•
•
•
•
•

Remote Battery Pack
AC Adapter
PC Software/Interface Kit
User Data Card
28 to 14 volt DC converter

iii

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Page iv

INTRODUCTION
Warranty

To obtain warranty service, see your local dealer
or 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 authorized warranty service facility.
GARMIN is fully committed to your satisfaction as
a customer. If you have any questions regarding
the GNC 250XL, 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
iv

Every GARMIN GPS is built to exacting standards to provide years of
trouble-free service. GARMIN warrants this product to be free from defects
in materials and workmanship for one year from the date of purchase.
GARMIN International, Inc. will at its sole option, repair or replace any
components which 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 International, Inc. assumes no responsibility for special, incidental,
punitive or consequential damages, or loss of use.
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.

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Page v

PART ONE: INTRODUCTION
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .i
Cautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ii
Accessories/Packing List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iii
Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iv
Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .v-vi
Key and Knob Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .vii-viii
GNC 250XL Takeoff Tour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-10

INTRODUCTION
Table of Contents

PART TWO: REFERENCE
Section 1: Navigation with the GNC 250XL ( N key) . . . . . . . . . . . . . . .11
Navigating and planning functions
Section 2: Communicating with the GNC 250XL . . . . . . . . . . . . . . . . . . .33
Using the GNC 250XL’s radio
Section 3: Waypoint and Database Information ( W key) . . . . . . . . . . . .37
Finding and using database and waypoint information

To quickly and easily locate information
on specific tasks, please refer to the Index
on page 103.

Section 4: Nearest Waypoints ( T key) . . . . . . . . . . . . . . . . . . . . . . . . .57
Finding nearest waypoints, SUAs and FSS/ARTCC frequencies
Section 5: Direct-to ( D key) & Route Navigation ( R key) . . . . . . . .62
Creating and using routes

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INTRODUCTION
Table of Contents

Page vi

Section 6: Messages and Unit Settings ( M key) . . . . . . . . . . . . . . . . . .75
Appendix A: NavData® and User Data Card Use . . . . . . . . . . . . . . . . .87
Appendix B: Installation and Maintenance of the GNC 250XL . . . . . . . .89
Appendix C: Simulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90
Appendix D: GNC 250XL Messages and Abbreviations . . . . . . . . . . . . .92
Appendix E: Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100
Appendix F: Map Datums . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101
Appendix G: Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103

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Page vii

Key and Knob Functions
B
Q
D

The power/volume knob controls unit power and radio volume.

INTRODUCTION
Key and Knob
Functions

The squelch button activates automatic squelch control.
The direct-to key performs an instant direct-to, allows you to enter a
waypoint, and sets a direct course to the destination.

T

The nearest key is used to obtain information on the 9 nearest airports,
VORs, NDBs, intersections, user waypoints and 2 nearest FSS/ARTCC
points of communication. The nearest key also accesses any active SUA
information. See Section 4 for more information on the nearest waypoints.

R

The route key enables you to create, edit, activate and invert routes. Searchand-rescue, parallel offset and closest point of approach functions are also
performed using the route key. See Section 5 for more route information.

W

The waypoint key is used to view information such as runways, frequencies, position and comments on airports, VORs, NDBs, intersections and
user waypoints. See Section 3 for more waypoint information.

N

The navigation key is used to view navigation and position information.
Planning operations are also performed using this key. See Section 1
for more information on navigation and planning operations.

The GNC 250XL is designed to minimize
keystrokes when performing operations. There are
typically several ways to perform the same operation. In general, using the knobs will decrease keystrokes and time spent using the GNC 250XL.
Experiment to find the most effective way to use
the GNC 250XL to your advantage.

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Page viii

INTRODUCTION
Key and Knob
Functions

This manual will describe entering data using the K
and O knobs. Experiment with them and become efficient
in entering data with the concentric knobs. This will greatly
reduce the amount of time required to navigate with the
GNC 250XL.

viii

M

The message key is used to view system messages. This key is also used to
access the GNC 250XL’s unit settings. See Section 6 for more information
on messages and unit settings.

@

The transfer key flip-flops the active and standby frequencies.

\

The clear key is used to erase information or cancel an entry.

E

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.

C

The cursor key is used to activate or deactivate the cursor in the separate
areas of the GNC 250XL. Pressing once will activate the cursor in the
comm ‘window’ and enable the pilot to change frequencies. Pressing twice
will activate the cursor in the GPS window (indicated by highlighted
characters in a GPS window field). It is used to highlight fields for data
entry, changing information or cycling through available options.

O

The outer knob is used to advance through pages, advance the cursor
or move through data fields.

K

The inner knob is used to change data or scroll through information that
cannot fit on the screen all at once.

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Page 1

The GARMIN GNC 250XL is a powerful navigational tool that provides pilots with accurate
navigational data and communication capability, along with a host of database information at your
fingertips. The Takeoff Tour is designed to familiarize you with the operation of the GNC 250XL,
including powering up the unit, changing frequencies, entering data and performing a simple
direct-to, and a limited introduction to the ‘Nearest’ functions. In addition, this section also briefly
covers the position, CDI and frequency pages available from the NAV key. These pages will be
used for most of your in-flight navigation.

TAKEOFF TOUR
Power On

The Takeoff Tour assumes that the GPSCOMTM and antennas have been properly
installed and you have not changed any of the GNC 250XL’s default settings. If you have
changed any of the factory default settings (position format, units of measure, selectable
fields, etc.), the pictures used may not match your configuration. Prior to using your GNC
250XL 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 250XL
The GNC 250XL’s power and volume are controlled using the B (power/volume) knob
at the bottom left of the unit. Rotating it clockwise will turn the unit on and increase the
radio volume. After turning the unit on, a welcome page will be displayed while the unit
performs a self test.

The welcome page appears when the GNC 250XL
is turned on. During the time this screen is
displayed, the GNC 250XL performs a self test to
ensure proper operation

The database page will appear, showing 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 is available for one-time or subscription purchase.
To acknowledge the database information:
1. Press the E key.

The database confirmation page shows the
effective date of the Jeppesen database on the
NavData Card.

1

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Page 2

TAKEOFF TOUR
Acquiring Satellites

Once the database has been acknowledged, the satellite status page will appear,
and the GNC 250XL will begin to collect satellite information. An ‘Acquiring’ status
will be displayed on the satellite status page, and the signal values on the bottom line
of the page will begin displaying numeric values. This is a good indication that you
are receiving signals and satellite lock will occur. Following the first-time use of your
GNC 250XL, the time required for a position fix will vary — usually from two to five
minutes.
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 and
working). If not, you will be prompted to enter the altitude with a ‘Need alt- Press
NAV’ message. If this message occurs, press the N key and use the K and O
knobs to enter the altitude shown on your altimeter. Press E when finished.

The satellite status page shows the ID numbers for
the satellites and the relative signal strength of
each satellite received. Turn the K knob to view
additional satellites.

If the GNC 250XL 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 (U), next to the M key, will also flash to alert you of a system
message — ‘Searching the Sky’.
To view a system message:
1. Press M.

The message page will appear and display the status or warning information
applicable to the receiver’s current operating condition.
‘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.

2

To return to the previous page after viewing a message:
1. Press M again.

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Page 3

While the GNC 250XL 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 250XL’s display can be broken down into two separate ‘windows’, the comm
window (the top line of the display) and the GPS window (the bottom three lines of
the display).
Active

{

TAKEOFF TOUR
Selecting Comm Frequencies

Comm Window

Standby

}

{

}

GPS Window

The C key is used to activate the cursor in a particular window (see right) to
provide access to various comm and navigation features. To select the active frequency,
you must first enter the frequency in the standby field, and use the @ key to move it
to the active field.

Status page with cursor active in comm window.

To change the standby communication frequency:
1. Press C once to activate the cursor in the comm window.
2. Rotate the outer knob (O) to select the MHz, and the inner knob (K) to select the kHz of
the desired frequency.
To place the standby frequency in the active field, press @.

Once you’ve entered the active frequency, simply repeat steps 1 and 2 to enter the
standby frequency. After both frequencies have been entered, you may elect to keep
the comm window ‘hot’ by leaving the cursor on the standby frequency, or remove the
cursor by pressing the C key twice.

To switch the active and standby frequencies, press
the @ key. Switching the active and standby
frequencies will not remove the cursor from the
comm window.

3

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Page 4

TAKEOFF TOUR
Position Page

After the GNC 250XL acquires satellites and computes a position, the position page will
appear automatically, and you’ll be informed with ‘Ready for navigation’ on the message page.
Altitude, MSA or ESA

Position (lat/lon)

{

250xl manual 2

Reference Waypoint Field

The map page combines a moving map display
and navigation data for complete situational
awareness.

The position page displays your present latitude and longitude, altitude and a reference waypoint field. The altitude and reference waypoint fields are also selectable (see Section 1 for more
information) to allow you to configure the unit to your own preferences. The default settings are:
• Altitude— Your present GPS altitude
• Present Position— Latitude and longitude displayed in degrees/minutes
• Reference Waypoint— The bearing and distance to the nearest airport
The position page is one of seven pages available under the GNC 250XL’s N key:
• CDI page
• NAVCOM page
• Satellite status page
• NAV menu 2

The navigation communications (NAVCOM) page
provides a complete list of airport frequencies at
your departure and arrival airports.

4

• Map page
• Position page
• NAV menu 1

During most flights, the Position, CDI (course deviation indicator), Map and NAVCOM pages
will be the primary pages used for navigation. These pages are accessible by pressing the N key
and rotating the outer knob, or by pressing the N key repeatedly.

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Page 5

The GNC 250XL uses direct point-to-point navigation to guide you from takeoff
to touchdown in the VFR 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.

TAKEOFF TOUR
Direct-To
Navigation

To select a direct-to destination:
1. Press the D key. The CDI page will appear with the destination field highlighted.
2. Rotate the K knob 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 O knob 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 direct-to confirmation page will appear.
6. Press E to confirm the destination.

Once the direct-to destination is confirmed, the CDI page will appear with the
destination indicated in the lower left hand corner of the screen. Your present speed
and track over the ground, and the distance and estimated time enroute to your destination are also displayed. The graphical CDI, located at the top left of the screen, displays your position relative to the desired course and provides turn anticipation and
waypoint messages during route navigation.

The CDI page without a direct-to destination or
active route appears blank, except for ground
speed (GS) and track (TRK) figures.

When a destination is selected the direct-to
confirmation page appears to verify the
destination you selected.

5

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Page 6

TAKEOFF TOUR
CDI & Map Pages

In addition to the destination field and graphical CDI, the GNC 250XL CDI page
features four selectable fields for various navigation data so that the page may be configured to your own preferences (see Section 1 for more information). The default settings for the CDI page are:
• Ground Speed (gs)— Your present speed over the ground in knots
• Distance (dis)— The distance to your destination in nautical miles
• Desired Track (dtk)— The course between active from and to waypoints
• Estimated Time Enroute (ete)— The time to your destination based
upon your present speed and course in hours and minutes

CDI page with ‘trk’ and ‘eta’ displayed.

The next page available from the N key is the map page. The map page combines the primary navigation information from the CDI page – distance to waypoint,
ground speed and track – with a moving map display. The moving map display shows
your current position (using an airplane symbol or a diamond symbol) relative to nearby airports, VORs, NDBs, intersections, user waypoints and airspace boundaries.
The map page can be divided into three main sections:

{

Map Display

Comm
Frequencies

CDI page with ‘brg’ and ‘trk’ displayed.

6

Data Fields

The communication frequencies are located in the upper left corner of the page,
instead of across the top line as on other pages. The top frequency is the active frequency, with the standby frequency directly below.

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Page 7

Airspace
Boundaries

TAKEOFF TOUR

Airport Waypoint

Map Page

Present
Position

The map display occupies the right side of the display. Your present position is indicated by a plane symbol (in track up mode) or a position diamond (in other orientation modes), with your route displayed as a solid line. Nearby airports, navaids and
user waypoints may be depicted on the map; with unique identifying symbols for
each waypoint type. Boundaries for special use and controlled airspaces can also
appear on the map display. You may select which features are shown on the map
using the map setup page (see page 76).
Distance to Waypoint

Destination
Waypoint

DTK

GS

The map display may be oriented along your
ground track (track up), course (desired track up)
or fixed at north up. Desired track up or north up
settings show your present position with a diamond symbol instead of the airplane symbol.

TRK
Map
Scale

The data fields on the map page indicate distance to destination waypoint,
desired track, ground track, ground speed and map scale. The destination waypoint
name and desired track appear on the left side of the page, below the communication
frequencies. The other data fields are located at the corners of the map display as
shown in the illustration above, and may be removed by pressing \.

Communication frequencies are shown in the top
left corner of the map page, instead of across the
top line as shown on other GNC 250XL screens.

7

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Page 8

TAKEOFF TOUR
Map Scales
NAVCOM Page

The map display has 14 available ranges from 0.5 to 300 (nautical miles, statute miles
or kilometers) representing the vertical height of the map. The map scale is controlled by the inner knob (K), with the current scale displayed in the lower right
corner of the page.
To select a map scale:
1. Rotate the K knob clockwise to increase the map scale and show a larger area.
2. Rotate the K knob counterclockwise to decrease the map scale and show a smaller area.

To change the map scale rotate the K knob clockwise to increase the scale or counterclockwise to
decrease the scale.

Another page available under the GNC 250XL’s N key is the navigation
communications (NAVCOM) page. It provides you with a complete list of airport
frequencies at your departure and arrival airports, allowing convenient selection of
frequencies you’ll need along your flight path. If you do not have an active departure
airport, the navigation communications page will display the frequencies for the
airport nearest your departure position.
To view the NAVCOM page from the map page, rotate O one stop to the right.

The NAVCOM page lists your departure and arrival airports on the left side of the
page, with all the database frequencies listed in a column down the right side of the
page. To scroll through the list of frequencies, simply rotate the inner knob (K) in
the direction of the arrow prompts at the bottom left of the page.
To place a frequency from the list in the standby field:
The NAVCOM page lists the frequencies for your
departure and arrival airports. To place a frequency from this list on standby, highlight the
desired frequency and press E.

8

1. Press the C key twice to activate the cursor in the GPS window.
2. Use the O knob to select the desired frequency. Press E to place the frequency in
the standby field. The cursor will automatically advance to the next frequency on the list.

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Page 9

Once a direct-to is activated, the CDI page will provide navigation to the destination until the direct-to is cancelled or another direct-to destination is activated.
To cancel a direct-to from the CDI page:
1. Press the C key twice to activate the cursor in the destination field.

TAKEOFF TOUR
Cancelling a Direct-To
Nearest Waypoints

2. Press \.
3. Press E.

The GNC 250XL’s T key provides the nine nearest airports, VORs, NDBs, intersections, user waypoints and any SUA (special use airspace) alerts, as well as the two
closest FSS (Flight Service Station) and center (ARTCC) frequencies for your present
position. The nearest waypoint feature is a handy safety feature that may be used to
execute a quick direct-to in case of an in-flight emergency or to review the closest facilities to your present position. The nearest feature can also be used to quickly find the
contact frequency of the nearest airport and enter it in the standby field.

The nearest airport page shows up to nine
nearest airports from your present position.

To view the nine nearest airports:
1. Press the T key. The nearest airport will be displayed, with the range and bearing from
your present position, along with elevation, frequency and runway data.
2. To review the rest of the nearest airport list, rotate the K knob to the right.
To place a nearest airport frequency in the standby field:
1. Press E. Press the @ key to place the frequency in the active field.
To view the nearest list for other waypoint categories (VOR, NDB, etc.):

To place a nearest airport frequency in the standby field, press E.

1. Rotate the O knob to the right, or press the T key repeatedly.
2. Rotate K to scroll through the list.

9

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Page 10

TAKEOFF TOUR
Nearest Airports
Shutting Down

Once the nearest airport (or any other nearest waypoint) page is displayed, the
selected waypoint can be quickly reviewed or selected as a direct-to destination.
To review the selected waypoint from the nearest waypoint list:
1. Press C twice to activate the waypoint field.
2. Press E to display the waypoint identification page.
3. Rotate O to view any additional waypoint information available.
4. Press T to return to the nearest waypoint page.
To select a nearest waypoint as a direct-to destination:
1. Press the D key. The direct-to confirmation page for the selected waypoint will appear.

To view additional nearest airports, rotate the
K knob.

2. Press E to confirm.

Congratulations! You’ve now gone through the basic operation of the GNC 250XL.
We encourage you to experiment with your new GPSCOM to get to know all the
advanced navigation features it has to offer. If you’d like a little more practice, try
using the built-in simulator described in Appendix C. An optional AC adapter will
even let you plan and simulate flights in the comfort of your home or office.
To turn the GNC 250XL off:
1. Turn the B knob to the left until the unit shuts off.

To review a nearest waypoint, highlight the identifier and press E.

10

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Page 11

Section 1
Navigation Key

NAV KEY

The GNC 250XL features seven navigation pages to provide various position,
course, speed, status and planning information. The pages may be viewed by pressing
the N key and rotating the outer knob, or by pressing the N key repeatedly.
CDI page

Map page

Overview

SECTION

1

NAVCOM page

Position page

NAV Menu 2

NAV Menu 1

Satellite status page

The CDI, map, NAVCOM and position pages are the primary pages used during
in-flight navigation, while the nav menu and status pages offer access to planning,
calculation and status functions. Note that rotating the outer knob clockwise will
continuously cycle through all the nav pages, whereas turning the knob counterclockwise will stop the page selection sequence at the CDI page.
Whenever the N key pages are in use, the indicator light (U) next to the N
key will illuminate. If the GNC 250XL requires you to enter data on a navigation
page, a message prompt with specific instructions will appear and the indicator will
flash. If you leave the NAV page sequence for another set of pages, the last NAV page
displayed will appear when you return to the nav sequence.

Remember! The NAV pages will only display information
AFTER the position and navigational information has been
calculated from the satellites. If you are on the Position
page before the unit has calculated a position, you will be
able to enter an approximate position and altitude. This is
helpful in speeding satellite acquisition if the unit has
moved a great distance with the power off.
If you are not sure the GPS is actively calculating position,
check the receiver status field for ‘2D NAV’ or ‘3D NAV’ by
pressing the N key and rotating the outer knob until the
Satellite Status page appears. The current receiver status is
displayed at the top left of the page.

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NAV KEY
CDI Page

The GNC 250XL’s CDI page provides you with the important information needed
to navigate directly to your destination. The destination field, located at the bottom
left of the page, displays the current destination waypoint or active route leg being
navigated. If no direct-to destination or route is being navigated, the destination field
will remain blank.
Ground Speed
Messages
or CDI
Direction
Field

Distance
Field

The TO/FROM arrow indicates whether you are
heading to (an up arrow) the waypoint or if
you’ve passed the waypoint (a down arrow).

Active Waypoint

Time or Direction Field

The graphical CDI (course deviation indicator) at the top left of the page shows
your position relative to the desired course (the moving D-bar) to the destination
waypoint. The TO/FROM arrow in the center of the scale indicates whether you are
heading to (an up arrow) the waypoint or if you have passed the waypoint (a down
arrow). The default setting of the CDI scale is 5.0 nm. If you are not navigating to a
destination, the CDI field will display a ‘no actv wpt’ message, and only speed and
track data will be available. The CDI field is also used to display the GNC 250XL’s
turn anticipation and waypoint alert data during route operations (see section 5).
The CDI page will display ‘No actv wpt’ in the
CDI field if there is no destination waypoint
selected using the D key and no active route.

12

In addition to displaying your active destination and the course deviation scale,
the CDI page features four selectable fields for various distance, direction and time
options. This allows you to configure the CDI page to your preferences. The default
settings are ground speed, distance, desired track and estimated time enroute.

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The following functions may be displayed in the ground speed field:

NAV KEY

• gs— Your present speed over the ground.
• str— Steer direction and distance, or digital crosstrack error. An ‘L’ or ‘R’
indicates which direction to steer, while the distance value indicates how far you are off course.

SECTION

1

Configuring the
CDI Page

The following functions may be displayed in the distance field:
• dis— Distance from present position to the ‘active to’ waypoint.
• str— Steer direction and distance, or digital crosstrack error. An ‘L’ or ‘R’
indicates which direction to steer, while the distance value indicates how far you are off course.

WPT 2
NORTH

The following steering functions may be displayed in the direction field:
brg— Bearing, the direction from your present position to the waypoint.
cts— Course to steer to reduce cross track error and re-intercept course.
dtk— Desired track, the course between the active from and to waypoints.
trk— Track, the direction of movement relative to the ground.
trn— Turn, the direction and degrees to turn to get back on course.

DIS

•
•
•
•
•

DT
K

NORTH

BRG
ST

The following information can be displayed in the time field:
•
•
•
•

eta— Estimated Time of Arrival (at the active to waypoint).
ete— Estimated Time Enroute (to the active to waypoint).
trk— Track, or the direction of movement relative to the ground.
vn— Vertical Navigation, or VNAV. If VNAV has been activated, this field
indicates either the elapsed time before the VNAV maneuver is to
begin or the VNAV altitude (the suggested altitude you should be flying in order to complete the maneuver).

R

G

TRK

S

L

R
AI

PL

AN

E

WPT 1

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NAV KEY

To change any of the selectable fields on the CDI page:
1. Press C twice to activate the cursor in the GPS window.

CDI &
Map Pages

2. Rotate O to highlight the field you would like to change.
3. Rotate K to change the field to display the desired information.
4. Rotate O to highlight another field, or C to finish.

{

Map Display

Comm
Frequencies

Data Fields

On the map page the active and standby communication frequencies are in the upper left corner of
the page. The active frequency is on top.

The next page available from the GNC 250XL’s N key is the map page. The
map page displays your present position, using an airplane symbol (in track up
mode) or a position diamond (in other orientation modes), along with nearby airports, VORs, NDBs, intersections, user waypoints and airspace boundaries. Note: If
the GNC 250XL is unable to determine a GPS position the present position symbol
will not appear on the map page.

To change the map scale rotate the K knob clockwise to increase the scale or counterclockwise to
decrease the scale.

14

The top left corner of the page indicates the active and standby communications frequencies — unlike other GNC250XL screens which display both frequencies across the top line — with the active frequency on top.

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The map display occupies the right side of the display and shows your position
relative to nearby airports, navaids, user waypoints and airspaces. Different symbols
are used to distinguish between waypoint types. The identifiers for any on-screen
waypoints can also be displayed. Special-use and controlled airspace boundaries
appear on the map, showing the individual sectors in the case of Class B or Class C
airspace. The map display can be configured to display airports, navaids, user waypoints, airspaces only at certain scales or these items may be disabled entirely (see
page 76). This allows you to de-clutter the map display at larger scale settings.

NAV KEY
Map Page

SECTION

1

The map display can be set to 14 different scale settings from 0.5 to 300 (nautical
miles, statute miles or kilometers). The scale represents the top-to-bottom distance
covered by the map display.
To select a map scale:
1. Rotate the K knob clockwise to increase the map scale and show a larger area.

The map page, showing only airports and airspaces on the map display.

2. Rotate the K knob counterclockwise to decrease the map scale and show a smaller area.

The autozoom feature will automatically adjust from an en route scale of 300
through each lower scale, stopping at a scale of 1 as you approach your destination
waypoint. The autozoom feature is turned on/off from the map setup page described
on page 76.
The orientation of the map may be fixed at ‘north up’, or set to ‘desired track up’
(dtk up) or ‘track up’ (trk up). The ‘north up’ setting will keep the top of the map
display fixed on north. ‘Track up’ will cause the map to rotate so the top of the map
is the direction you are heading. ‘Desired track up’ keeps the map display fixed along
your desired course. Map orientation is changed on the map setup page described on
page 76.

The map page, showing airports, airspaces, VORs
and NDBs on the map display. The data fields
located at the corners of the map display may be
removed by pressing \.

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Page 16

NAV KEY
Map &
NAVCOM Pages

Navigation data is also provided on the map page to guide you during your flight.
The destination waypoint name and desired track (dtk) appear on the left side of the
page, below the communication frequencies. Additional data fields may be displayed
at the corners of the map display (or removed by pressing \), as follows:
Distance (dis) to waypoint
Ground speed (gs)
Ground track (trk)
Map scale

- upper left corner
- upper right corner
- lower left corner
- lower right corner (cannot be removed)

The NAVCOM page lists the frequencies for your
departure (or nearest) and arrival airports in the
following order:

16

Departure

Arrival

• Unicom
• ATIS
• Clearance Delivery
• Clearance Pretaxi
• Ground
• Tower
• Multicom
• Other
• Departure
• TCA
• TMA
• CTA
• ARSA
• TRSA

• ATIS
• Approach
• Arrival
• TCA
• TMA
• CTA
• ARSA
• TRSA
• Tower
• Multicom
• Other
• Ground
• Unicom

The next page available from the GNC 250XL’s N key is the navigation communications (NAVCOM) page. The NAVCOM page provides a list of the airport
frequencies at your departure and arrival airports, allowing convenient selection of
frequencies you’ll need along your flight path. To scroll through the list of frequencies, rotate the inner knob (K) in the direction of the arrow prompts at the bottom
left of the page.
The frequencies displayed for the departure and arrival airports are listed in the
order you are most likely to use them (see left), with the available frequencies displayed to the right of the airport identifier. If you do not have an active route with a
departure airport, the NAVCOM page will display the frequencies for the airport
nearest your departure position.

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If a frequency has sector or altitude restrictions, the frequency will be followed by
a ‘brg?’ indication.
To view restrictions on a frequency:
1. Press C twice to activate the cursor in the GPS window.

NAV KEY
NAVCOM Page

SECTION

1

2. Rotate O to highlight the ‘brg?’ next to the frequency you wish to view.
3. Press E to begin viewing restrictions.

Once you begin viewing restrictions, you can view any additional frequencies for
the selected airport by rotating K. (Note: An arrow prompt displayed next to the airport identifier indicates additional frequencies are available.) You can also view the
other airport information pages by rotating O. Information contained on these pages
is covered in Section 3. To return to the NAVCOM page, press N.

NAVCOM page with receive only (rx) frequencies
and frequencies with restrictions (brg).

Some frequencies in the NAVCOM page have tags which designate their usage:
‘tx’ – transmit only
‘pt’ – part time frequency

‘rx’ – receive only

To make any of the frequencies on the NAVCOM page the standby frequency:
1. Press C twice to activate the cursor in the GPS window.
2. Rotate O until the desired frequency is highlighted.
3. Press E to make the highlighted frequency the standby frequency. The cursor will automatically advance to the next frequency on the list.

Frequency restrictions on 124.60, showing range
of applicable radials from 130º through 309º.

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NAV KEY
Position Page

The GNC 250XL position page displays your present latitude and longitude,
altitude and a reference waypoint field. The altitude and reference waypoint fields are
selectable to configure the page to your own preferences and current navigation
needs.
Altitude, MSA or ESA

Position (lat/lon)

{

250xl manual 2

Reference Waypoint Field
Position page displaying MSA.

The altitude field can display either the present altitude, minimum safe altitude
(MSA) or enroute safe altitude (ESA). MSA is the recommended minimum altitude
within a ten mile radius of your present position. ESA is the recommended minimum
altitude within a ten mile radius of your course on an active route or direct-to. MSA
and ESA altitudes are calculated from information contained in the database and generally include mountains, buildings and other permanent features (see left).
To change the altitude field:
1. Press C twice to obtain a cursor in the GPS window.

18

The same position page displaying ESA. MSA and
ESA are computed based on data stored in the
NavData card. This information cannot be solely
relied upon as an absolute measure of safe altitude
in your area, particularly if the data card is out of
date. Consult current charts and NOTAMS for
more complete information.

2. Rotate O until the ‘alt/ESA/MSA’ field is highlighted.
3. Rotate K to display the desired data. Press C to return to normal navigation.

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The position page also features a reference waypoint field, located at the bottom
of the page, to indicate your bearing and distance from a selected waypoint. The reference waypoint field can display the following:
• Range, bearing and identifier from the nearest airport (default), VOR,
NDB, intersection, or user waypoint
• Range, bearing, and identifier from a user specified waypoint

NAV KEY
Reference
Waypoint Field

SECTION

1

The default setting is to display the nearest airport.
To change the reference waypoint field to display the nearest airport, VOR, NDB,
intersection, user waypoint or the range and bearing from a user selected waypoint:
1. Press C twice to activate the cursor in the GPS window.
2. Rotate O to highlight the category field after the fr.
3. Use K to choose which waypoint type you would like displayed. (Choose ‘wpt’ if you
would like range and bearing from a specific waypoint to be displayed.)

Position page displaying the nearest airport
(KIXD) as the reference waypoint.

4. Press C to remove the cursor, or:

If you have selected ‘wpt’:
5. Rotate O to advance the cursor to highlight the identifier field.
6. Use the K and O knobs to enter the identifier name. (This waypoint identifier can be
an airport, VOR, NDB, intersection, or user waypoint.) Press E.
7. Press C to confirm the selection.

This allows the distance and bearing from any waypoint to be displayed continuously on the position page, which may be useful when trying to locate your position
on a sectional chart.

Position page displaying the ‘TOP’ VOR as the reference waypoint. This configuration can be used to
help monitor your distance and radial from a
waypoint of your choice.
Note: The waypoint category is listed as ‘wpt’
rather than ‘VOR’ because the GNC 250XL is not
using the nearest VOR for the reference waypoint.

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NAV KEY
Satellite
Status Page

The GNC 250XL’s satellite status page provides satellite information to monitor
GPS coverage and receiver performance. This is helpful when you may be experiencing low signal levels due to poor coverage or installation problems.
To view the satellite status page:
1. Press N and rotate O until the satellite status page appears.
EPE/DOP
Receiver Status

EPE/DOP
value

Satellites in view
Satellite status page with ‘EPE’ displayed.
Estimated Position Error (EPE) gives an overall
measure of your position accuracy in feet or
meters.

Signal strength of
satellite being tracked (1-9)

Satellite in view
but not receiving signal

The top line of the status page displays the receiver status and the current position accuracy in DOP or EPE. The default setting is DOP.
The following functions may be displayed in the DOP/EPE field:

Satellite status page with ‘DOP’ displayed.
Dilution of Precision (DOP) measures relative
accuracy from 1 to 10.

20

• dop— Dilution of Precision, a measure of the satellite geometry quality
and relative accuracy of your position, with 1 indicating good
geometry and 10 indicating poor.
• epe— Estimated Position Error, an overall measure of your positional
accuracy in feet or meters using signal and data quality, receiver
tracking status and DOP.

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To change the DOP/EPE field:
1. Press N and rotate O to display the satellite status page.
2. If the desired field (EPE or DOP) is not displayed, press C twice.
3. Use K to change between ‘epe’ and ‘dop’. Press C to finish.

NAV KEY
Receiver
Status Field

SECTION

1

The receiver status field, located at the top left of the page, can display the following messages under various conditions:
Search Sky - The GNC 250XL is searching the sky for visible satellites.
You will be informed with the message ‘Searching the Sky’.
Acquiring - The GNC 250XL is acquiring satellites for navigation.
2D Nav The GNC 250XL is in 2D navigation mode. If your installation does not include an altitude serializer, you must enter
the altitude manually (see page 2). ‘2D Dif Nav’ will appear
when you are receiving DGPS corrections in 2D mode.
3D Nav The GNC 250XL is in 3D navigation mode and will compute
altitude. ‘3D Dif Nav’ will appear when you are receiving
DGPS corrections in 3D mode.
Simulator - The GNC 250XL is in simulator mode, which should only be
used for practice and trip planning. Never use simulator
mode for actual navigation.
Poor Cvrg - The GNC 250XL cannot acquire sufficient satellites for navigation.
Need Alt - The GNC 250XL needs altitude in order to start/continue
navigation. Go to the position page and enter the altitude.
Not Usable - The GNC 250XL is unusable due to incorrect initialization or
abnormal satellite conditions. Turn the unit off and on again.
Autolocate - The GNC 250XL is looking for any satellite whose almanac
has been collected. This process can take up to five minutes.

‘Acquiring’ satellites for navigation. In this case,
the satellites are being received, but the data is
still being collected before a position can be
determined.

‘Searching the Sky’ for satellites. No satellite
almanac data exists in the GNC 250XL. It must
be recollected from the first available satellite.

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NAV KEY
Satellite Data Page

The second and third lines of the satellite status page provide the satellite number
and signal strength of each satellite in view. The satellite status page shows signal
strength for up to eight satellites at a time. If additional satellites are being received
an arrow on the ‘sat’ line will indicate additional data is available.
To view additional satellites:

1. Rotate K to view more satellites.
Additional information regarding each satellite’s azimuth, elevation and other data
is also available.
To view individual satellite information:
Viewing individual satellite information.

1. Press N and use O to display the satellite status page.
2. Press C twice to activate the cursor in the GPS window.
3. Use O to highlight the satellite number you wish to view and press E.

This will display the satellite data page, showing the selected satellite’s number,
elevation angle, rise or fall indication, User Range Accuracy (URA, or the range
measurement accuracy as determined by the satellite), azimuth and signal strength.
To view other satellites:
4. Rotate K to view information for the next satellite.
5. Rotate O and press C on the satellite status page when you are finished.

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Page 23

In addition to the other five pages, the GNC 250XL features two menu pages to
perform a host of planning and navigation functions. NAV Menu 1 provides access to
the following functions:
• Trip Planning
• Density altitude/true airspeed calc.
• Fuel Planning
• Winds aloft calculations
• VNAV Planning
• Checklists

NAV KEY
NAV Menu 1
Trip Planning

SECTION

1

To display NAV Menu 1:
1. Press N.
2. Rotate O until NAV Menu 1 is displayed.

Trip Plan is the first function listed on NAV Menu 1 and allows the pilot to view
distance, ESA, bearing and estimated time enroute (ETE) between any two waypoints,
and for programmed route legs. The ground speed can be varied manually to calculate several possible ETEs.

NAV Menu 1

To use the trip planning function:
1. Press N and rotate O until NAV Menu 1 is displayed.
2. Press C twice, then E to access trip planning.
3. Rotate K to select waypoint mode or desired route number and press E.
4. For direct-to navigation, use K and O to enter the ‘to’ and ‘from’ waypoints. Press
E to accept the waypoints. To use your present position as a waypoint, leave the waypoint field blank.
5. For route calculations, choose either ‘cum’ for cumulative data (from beginning to end) or
the leg desired by rotating K.
6. Use K and O to enter the ground speed. Press E to calculate the values and C
to finish.

Trip planning with values calculated between two
waypoints.

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NAV KEY
Density Altitude &
True Airspeed

The density altitude/true airspeed function is also accessed from NAV Menu 1.
Density altitude is the theoretical altitude at which your aircraft will perform depending
on several environmental conditions, including air pressure and total air temperature
(the temperature including the heating effect of speed, read on a standard outside temperature gauge on most aircraft). True airspeed considers the same factors.
To calculate the density altitude and true air speed:
1. Press N and rotate O until NAV Menu 1 is displayed.
2. Press C twice and rotate O to highlight ‘Dalt/tas?’.
3. Press E to access the density altitude page.
4. Use K and O to enter the indicated altitude (‘ialt’) and press E.

Density altitude/true airspeed page

5. Use K and O to enter the calibrated airspeed (‘cas’). Press E.
6. Use K and O to enter the air pressure (‘pres’) and press E.
7. Use K and O to enter the total air temperature (‘tat’).
8. Press E and the density altitude and true airspeed will be calculated and displayed.
9. Press C to remove the cursor.

If your installation includes components to provide any of the information
required on the density altitude page, they will be used as the defaults.

Fuel planning page showing calculation from present position to ‘KDAL’.

24

The fuel planning page will display fuel requirements for both direct-to navigation and programmed routes. The fuel planning function requires the pilot to enter
the initial amount of fuel on board and the flow rate. You may also enter different
ground speeds to view various information based on different travel times. If your
installation is interfaced to a fuel flow sensor, the flow rate and other information will
be supplied by the fuel flow sensor.

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To perform fuel planning operations:
1. Press N and rotate O until NAV Menu 1 is displayed.
2. Press C twice and rotate O until ‘Fuel Plan?’ is highlighted. Press E.
3. Rotate K to select either ‘wpt’ for direct navigation or the desired route number. Press E.

NAV KEY

SECTION

NAV Menu 1
Fuel Planning

1

4. For waypoint-waypoint navigation, use K and O to enter the ‘to’ and ‘from’ waypoints.
Press E to accept the waypoints. To use the present position as a waypoint, leave the
corresponding waypoint field blank.
5. For route calculations, choose either ‘cum’ for cumulative route fuel requirements
(from beginning to end) or the leg desired by rotating K .

If leg is selected, it displays the amount of fuel required to fly until that leg is complete.
For example: The fuel required to complete leg 2 is leg 1 + leg 2.
Fuel required to complete leg 4 is leg 1 + leg 2 + leg 3 + leg 4.

Fuel planning page showing calculations between
two waypoints.

6. Rotate O to advance the cursor to ‘fob:’ or ‘gs:’ (depending on which is displayed).
7. Use K and O to enter the fuel on board or the ground speed. Press E.
8. Rotate O back two positions to highlight the ‘fob:’ or ‘gs:’ field again.
9. Rotate K to display the other information. Press E.
10. Use K and O to enter the remaining data. Press E.
11. Use K and O to enter the flow rate, in units per hour, if needed. Press E.

The GNC 250XL will calculate the range and endurance (i.e., how long the fuel
will last) of your aircraft. These are found in the first field on the bottom row of the
page. The amount of fuel left on board (lfob) and reserve time after the selected
direct-to, leg or route is flown are displayed in the second field on the bottom row.

Fuel planning page with other information
indicating ‘endurance’ and ‘reserve’ times.

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NAV KEY
Winds Aloft &
VNAV Functions

The GNC 250XL’s winds aloft function is used to calculate the true direction and
speed of any winds, and indicates whether you are flying with a head wind or tail
wind, and the wind speed.
To calculate winds aloft:
1. Press N and rotate O until NAV Menu 1 is displayed.
2. Press C twice and rotate O until ‘Winds?’ is highlighted. Press E.
3. Use K and O to enter your present heading in the ‘hdg:’ field. If your installation
includes a fuel/air data computer, this will be displayed automatically. Press E.
4. Use K and O to enter your true airspeed (TAS) in the ‘tas:’ field. If you have previously
calculated it using the density altitude/true air speed function, it will be displayed as the
default. Press E. The wind direction and speed and head/tail wind will be displayed.

Winds aloft page

The VNAV function calculates vertical speed requirements to reach a desired altitude before
or after a specified distance from a waypoint. This is helpful when you’d like to descend to a certain altitude near an airport or climb to an altitude before reaching a route or direct-to waypoint.
To calculate vertical navigation parameters:
1. Press N and rotate O until NAV Menu 1 is displayed.
2. Press C twice and rotate O until ‘Vnav Plan?’ is highlighted. Press E.
3. Use K and O to enter the initial (from) altitude. Your current GPS altitude will be displayed as the default. Press E.
4. Use K and O to enter the desired final (to) altitude. Press E.

Vertical navigation page

5. Use K and O to enter the distance from the waypoint. Press E.
6. Use K to select ‘before’ or ‘after’ the waypoint. Press E.

26

7. Use K and O to select the waypoint identifier (it must be a waypoint in the active route
or a direct-to waypoint). Press E.

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You will now notice that the vertical speed has been calculated, based on your
present speed. If you desire a more rapid climb or descent rate:
8. Use K and O to enter the new desired vertical speed, or press E to accept the
calculated value.

NAV KEY
NAV Menu 1
VNAV & Checklists

9. Press E to activate the vertical navigation function.

SECTION

1

If you enter a value greater than the value computed by the GNC 250XL, the time
before the maneuver is to begin will be displayed. When the countdown reaches 15 seconds, you will be informed with the message ‘Start altitude chng’. The VNAV function will
automatically be cancelled if the active direct-to or route is changed in any way, and you
will be informed with a ‘VNAV cancelled’ message.
The GNC 250XL allows you to create up to nine checklists with 30 items each to
remind you of repetitive tasks. These checklists can be called up at any time for review
and are useful for creating pre-flight checklists, landing checklists, emergency procedures, etc. Each name or function can have up to 16 characters each.
To create a checklist:

VNAV displayed on CDI page. The VNAV altitude
should be compared with the reading on the aircraft altimeter to ensure you are on the proper
climb/descent profile.

1. Press N and rotate O until NAV Menu 1 is displayed.
2. Press C twice and rotate O until ‘Chklist?’ is highlighted. Press E.
3. Press C and use O to highlight the checklist you would like to create or edit.
Press E.
4. Use K and O to enter the title of the checklist. Press E.

This will display the checklist items page. On this page you can enter each task,
such as ‘Check Fuel’.

Checklist catalog page.

5. Use K and O to enter the checklist item. Press E.
6. You may repeat step 5 to enter additional items, or press C to finish.

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To execute a checklist:

SECTION

1

NAV KEY
Checklists
Approach Timer

1. Press N and rotate O until NAV Menu 1 is displayed.
2. Press C twice and rotate O until ‘Chklist?’ is highlighted. Press E.
3. Use O to highlight the checklist you would like to see. Press E.
4. Press E to check off list items.
To delete a checklist item or an entire checklist:
1. To delete a checklist item, highlight the desired item and press \, followed by E.
2. To delete an entire checklist, highlight the desired list and press \, followed by E.

Executing a checklist.

The GNC 250XL’s NAV Menu 2 provides access to various timer and planning functions, including:
• Approach timer
• Clock (Date and time)
• Trip Timer
• RAIM Prediction
• Scheduler messages
• Sunrise and sunset calculations
The approach timer acts as either a count up or a count down timer that can be
set or reset at any time.
To activate/change/view the approach timer:
1. Press N and rotate O until NAV Menu 2 is displayed.
2. Press C twice and rotate O until ‘Appr Time?’ is highlighted. Press E.

NAV Menu 2

3. Rotate K to select either ‘Count up’ or ‘Count down’. Press E.
4. Use K and O to set the time from which to begin counting. Press E.
5. Rotate O to select the desired function: ‘Start’, ‘Stop’, or ‘Reset’. Press E to execute.

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When the count down timer reaches zero, you will be informed with a ‘Timer
expired’ message. The timer will then begin to count up, displaying the time since it
expired. The timer runs, if not altered, whenever the GNC 250XL is turned on.
The GNC 250XL clock function keeps track of both UTC time (Greenwich Mean
Time or Zulu Time calculated from the satellites) and local time, allowing you to
designate which format to use for all time displays. The local time and date can be set
without displaying local time on other GNC 250XL pages.

NAV KEY
Clock Function
Trip Timer

SECTION

1

To set the local date/time:
1. Press N and rotate O until NAV Menu 2 is displayed.
2. Press C twice and rotate O until ‘Clock?’ is highlighted. Press E.
3. Use K to select either ‘utc’ or ’local’ time to be displayed in the time fields. Press E.
4. Use K and O to set the local date. Press E.

Clock function set to display local time in the time
fields of all other GNC 250XL pages.

5. Use K and O to set the local time. Press E.
6. Press C to complete.

The GNC 250XL’s trip timer will automatically keep track of the duration of your
current trip and can be configured to run either when the GNC 250XL is on, or when
your ground speed exceeds a specified value (see section 6).
To view or reset the trip timer:
1. Press N and rotate O until NAV Menu 2 is displayed.
2. Press C twice and rotate O until ‘Trip time?’ is highlighted. Press E. The current
time of day, departure time and time enroute will be displayed.
3. To reset the timer, press E. To skip resetting the timer, press C.

To reset the trip timer, highlight ‘Reset?’ and
press E.

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NAV KEY
RAIM Prediction

The RAIM Prediction function allows you to confirm that GPS coverage is
available for a specific location or waypoint any day of the year. Receiver
Autonomous Integrity Monitoring performs checks to ensure that the GNC 250XL
will have adequate satellite geometry to work with during your flight. RAIM availability will be near 100% in Oceanic, En route and Terminal phases of flight.
To predict RAIM availability:
1. Press N and rotate O until NAV Menu 2 is displayed.
2. Press C twice and rotate O to highlight ‘RAIM Prd?’. Press E.
3. Rotate O to highlight the field which you would like to change.

Enter the time and date for RAIM prediction.

4. Use K and O to enter the waypoint name, or leave it blank to use your current
position. Press E to accept.
5. Use K and O to enter the ETA in hours and minutes (in local or UTC time, whichever
you have selected from the clock display), and the day, month and year. The current date
will be displayed automatically. Press E to accept.
6. Rotate O to highlight ‘Compute RAIM?’.
7. Press E to compute information.

When the computations are complete, the GNC 250XL will display whether or
not RAIM is available for the specified waypoint at the specified date and time. Refer
to the table on page 78 for specific RAIM protection limits as they relate to CDI scale
figures.
RAIM available for the entered time, date and
waypoint location.

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The scheduler function will display reminder messages (such as ‘Change oil’, ‘Switch
fuel tanks’, ‘Overhaul’, etc) after a specified time has elapsed. For example, if you enter
‘Change oil’ to be displayed in 30 hours, the message ‘Change oil’ will be displayed after the
GNC 250XL has been running in Normal mode for 30 hours. After appearing, the message
will be displayed each time the GNC250XL is turned on until it is changed or deleted.

NAV KEY
NAV Menu 2
Scheduler

SECTION

1

To enter a scheduled message:
1. Press N and rotate O to display NAV Menu 2.
2. Press C twice and rotate O until ‘Scheduler?’ is highlighted.
3. Press E.
4. Rotate O to highlight the message you would like to edit. To delete, press \,
then E.
5. Use K and O to enter the message. Press E.

The scrolling arrow prompt indicates which direction to scroll to view additional listings.

6. Use K and O to set the time to elapse before the message is displayed, in hours and
minutes, up to 99 hours and 59 minutes (this time is cumulative and counts whenever
the GNC 250XL is on in normal operating mode).
7. Press E.

You may edit another scheduled message by repeating steps 4, 5, 6 and 7, or if you
are finished, press C.
The scheduled message will appear after the timer
expires and reappear every time the GNC 250XL
is powered on until the message is changed.

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NAV KEY
Sunrise/Sunset
Calculations

The GNC 250XL’s sunrise/sunset planning function allows you to calculate the time
of sunrise or sunset at any waypoint or your present position for a specified date.
To calculate sunrise and sunset times at a waypoint or at your present location:
1. Press N and rotate O until NAV Menu 2 is displayed.
2. Press C twice and rotate O to highlight ‘Sunrise?’. Press E.
3. Use K and O to enter the waypoint identifier, or leave blank to use current position.
Press E.
4. Press E to accept the waypoint information.
5. Use K and O to enter the date desired.

Sunrise/sunset planning page showing UTC (Zulu)
sunrise and sunset times for ‘KROG’.

32

6. Press E and the sunrise and sunset times will be calculated and displayed.

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Section 2
Communicating with the GNC 250XL

COMM FEATURES
Overview

The GNC 250XL features a digital VHF radio that provides a seamless transition
from communication to navigation, bringing the two most important functions in flying together in one panel-mount unit. The GNC 250XL operates in the aviation voice
band, from 118.000 to 136.975 MHz, in 25 kHz steps.
Communication frequencies are selected by activating the cursor in the standby
frequency field and using the inner and outer knobs to dial in the desired frequency.
A frequency may also be quickly selected from the navigation database by simply
highlighting the frequency and pressing the E key. Once a desired frequency is displayed in the standby field, it may be made the active frequency by pressing the @
key. Note that the active frequency may not by accessed directly. Whenever the cursor is
active in the comm window, the standby frequency will be highlighted.

SECTION

2

CDI page with cursor inactive.

To access the standby frequency, press C.

This allows you to change the megahertz (number to the left of the decimal) by
rotating O and the kilohertz (number to the right of the decimal) by rotating K. If
you would like to keep the standby field ‘hot’ (ready for an immediate frequency
change), leave the cursor active in the comm window. To remove the cursor, press
C twice after you have selected the desired frequency.
To make the standby frequency the active frequency, press @.

The frequencies will be flip-flopped and you’ll be able to transmit and receive on
the frequency previously entered as standby. This can be done at any time, regardless
of cursor or GPS status.

CDI page with standby field active. To flip-flop the
frequencies, press @.

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COMM FEATURES
Overview
Auto-Tuning

During the course of navigating with the GNC 250XL, there may be times when
you need to quickly select a comm frequency while you are entering data in the GPS
window. Whenever data entry in the GPS window is interrupted by activating the
standby frequency field, the GPS field in use will become ‘splatted’, or blocked out.

To auto-tune from the nearest airport page,
press E.

Once the standby frequency has been entered, you may return to data entry by
pressing the C key. The cursor will return to the active GPS field at the point
where data entry was interrupted.
The GNC 250XL’s auto-tune feature allows you to quickly select any database
frequency in the GPS window as your standby frequency.
To select a frequency from a list, highlight the
desired frequency and press E.

To auto-tune a single frequency displayed in the GPS window:
1. Press E with the cursor inactive.
2. To make the standby frequency the active frequency, press @.

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To auto-tune a frequency from a list displayed in the GPS window:
1. Press C twice to activate the cursor in the GPS window.

COMM FEATURES

2. Rotate O to highlight the desired frequency.

Auto-Tuning
Volume & Squelch

3. Press E to make the selected frequency the standby frequency.

SECTION

2

Another useful feature integrating the GNC 250XL’s navigation and communication
capabilities is the Navigation Communications (NAVCOM) page, which is accessed
using the N key. See pages 16-17 for more on the NAVCOM page.
The GNC 250XL’s automatic squelch and volume controls are located at the
bottom left of the unit, near the NavData card slot.
To adjust the radio volume:
1. Rotate the B knob.

‘TX’ indicating radio transmission.

Whenever the GNC 250XL is powered up, the automatic squelch will be in the
‘on’ position, allowing only transmissions which are powerful enough for clear broadcast to be received. Manual squelch control is not available.
To override the automatic squelch control:
1. Press the Q key. Press Q again to return to automatic squelch.

Whenever the GNC 250XL is transmitting, a ‘tx’ icon will appear between the
active and standby frequency fields. If the microphone is stuck or accidentally left in
the keyed position, or if the headsets continue to transmit after the key is released, the
radio will automatically timeout after 35 seconds of continuous broadcasting. You’ll
also receive a ‘Stuck mic/Tx disabled’ message as long as the stuck condition exists.
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COMM FEATURES
Emergency
Channel Selection

The GNC 250XL’s emergency channel select feature provides a quick method
of selecting the 121.5 MHz frequency as the active frequency in the event of an
in-flight emergency. The emergency channel select is available whenever the unit is
on, regardless of GPS or cursor status, or loss of the display.
To automatically tune for emergency transmission:
1. Press and hold the @ key for more than two seconds.

The emergency channel (121.50) will appear in
the active field by pressing @ for more than
two seconds.

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Page 37

Section 3
Waypoint and Database Information
The GNC 250XL uses a Jeppesen NavData® card to provide position and facility
information for thousands of airports, VORs, NDBs and intersections. Each facility in the
database is stored as a waypoint with its own latitude/longitude, identifier (up to five letters and/or numbers), and other pertinent information. Up to 1,000 user waypoints may
also be created and stored in the GNC 250XL’s internal memory.
Waypoint Menu Page

Proximity Waypoints Page

Waypoints with Comments List

User Waypoint List

Waypoint information is available through four primary waypoint pages accessible
from the GNC 250XL’s W key. The waypoint pages may be scrolled through by pressing the W key and rotating the outer knob until the desired page is displayed, or by
pressing the W key repeatedly.

WPT KEY
Overview

SECTION

3

Please note that your GNC 250XL uses ICAO
identifiers for all airports. All U.S. airport identifiers
which contain only letters use the prefix ‘K’. For
example, Los Angeles International is KLAX under
the ICAO standard. Other airports, such as Otten
Memorial (3VS), that contain numbers in the
identifier, do not require the ‘K’ prefix. Many foreign
countries use two letter prefixes. For more
information on ICAO identifiers, contact:
Document Sales Unit
International Civil Aviation Organization
999 University Street
Montreal, Quebec
Canada H3C 5H7

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WPT KEY
Waypoint Categories
& Menu Page

The GNC 250XL organizes waypoints into one of five waypoint categories for
your convenience. Each waypoint category provides different types of detailed information for a selected facility:
• Airports - Identifier, city/state, country, facility name, position (lat/lon),
elevation, runways, fuel services and communication frequencies.
• VORs - Identifier, city/state, country, facility name, position (lat/lon),
frequency, magnetic variation, co-located DME or TACAN and weather
broadcast indication.
• NDBs - Identifier, city/state, country, facility name, position (lat/lon),
frequency and weather broadcast indication.

The waypoint menu page allows you to select the
desired waypoint type (or category).

• Intersections - Identifier, country, position (lat/lon), nearest VOR.
• User - Identifier (name), position (lat/lon), reference waypoint.
To view the waypoint information for a desired waypoint, select the waypoint
category from the waypoint menu page.
To choose a waypoint category (for viewing information):
1. Press W and rotate O to display the waypoint menu page. (If pressing W once
does not display the waypoint menu page, press W a second time.)
2. Press C twice and rotate O to highlight the desired waypoint category.

The airport position page shows the position,
field elevation and available fuels for the selected
airport.

38

3. Press E to accept the waypoint category. The waypoint identification or position page
for the selected category will appear with the waypoint identifier field ready for entry.

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After a waypoint category is selected, information for a waypoint may be viewed
by entering the identifier or name of the desired waypoint. Airports, VORs and NDBs
may be entered by either the identifier, name or the location (city) of the facility.
Intersections and user waypoints must be entered by the identifier.

WPT KEY

SECTION

Entering Waypoints

To enter a waypoint identifier:

3

1. With the cursor over the waypoint field, use K and O to enter the
waypoint identifier.

As the identifier is entered, the GNC 250XL’s Spell’N’FindTM feature will scroll
through the available database, displaying those waypoints matching the identifier letters you have entered to that point. When the desired waypoint is displayed, press
C to remove the cursor.
To obtain waypoint information by entering the facility name of the airport or
navaid, or its location:

Entering a waypoint by identifier.

1. Press W and rotate O to display the waypoint menu page.
2. Press C twice and rotate O to highlight the desired waypoint category.
3. Press E to accept the waypoint category.
4. Rotate O to highlight the middle field to enter location (city) OR:
Rotate O to highlight the bottom field to enter facility name or VOR/NDB name.
5. Use K and O to enter the location or the name, and press C to finish.

As the information is entered, the GNC 250XL will display any entries in its database that match the letters you have entered. If duplicate entries exist for the entered
identifier, name or location, additional entries may be viewed by rotating K. Once
the desired waypoint is displayed, press C to continue.

Entering a waypoint by city. Note that punctuation marks are not used when entering locations
or names. Use spaces, where appropriate, to identify these marks. For example, St. Louis would be
entered as “ST LOUIS” without a period.

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WPT KEY
Airport Information

Once a waypoint category and identifier have been selected, the GNC 250XL will
provide extensive information through a set of waypoint pages for the selected category. The pages available for each waypoint category are presented here in the order
they appear on the waypoint menu page: airports, VORs, NDBs, intersections and
user waypoints.
Airport Information
Airport Identification Page

Airport Comments Page

Airport Position Page

If the city or facility name information is too long
to fit the screen, the name will scroll across the
page every few seconds so the complete name can
be read.

Airport Runway Page

Airport Communication Page

To scroll through the airport pages:
The airport position page shows the position,
field elevation and available fuel types for the
selected airport.

40

1. Make sure the cursor is not present. If it is, press C.
2. Rotate O in either direction to scroll through the available pages.

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The GNC 250XL features five airport pages:
airport identification— allows entry of desired airport by identifier,
facility name or city; displays region and/or country of facility.
airport position— allows entry of desired airport by identifier; displays
latitude, longitude and elevation; indicates usage and fuel availability;
displays available approaches and airport control/radar capability.

WPT KEY
Airport Pages

SECTION

3

airport communication— allows entry of desired airport by identifier;
displays radio frequencies/usage, and sector and altitude restrictions.
airport runway— allows entry of desired airport by identifier; indicates
runway designations, length, surface and lighting information; displays
ILS/localizer and/or pilot-controlled lighting frequencies.
airport comments— allows entry of desired airport by identifier; displays
user comments for the selected airport.
Waypoint Type
and Identifier

Airport communication page. The down arrow
next to the identifier indicates additional frequencies may be displayed by rotating the K knob.

Region/Country

{

Location
(city/state)

Facility Name

The airport identification page displays a selected airport’s identifier, region and
country, city/state and facility name. The identification page is always the first airport
page available, allowing you to quickly review an airport facility or select another
facility by entering the identifier, facility name or city of the desired airport.

Airport runway page. The down arrow next to
the identifier indicates additional runways may be
displayed by rotating the K knob.

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The airport position page displays the latitude, longitude and elevation of the
selected airport, as well as usage or fuel availability, available approaches and airport
control/radar capability. The following descriptions and abbreviations are used on the
airport position page:

WPT KEY

SECTION

3

Airport
Position Page

1

2

Elevation— In feet or meters
Usage/Fuel— If the airport is for military use, it will display ‘military’.
If it is private, the GNC 250XL will display ‘private’. If it is a
public airport, it will display the fuel type(s) available:
• av gas— 80-87 octane, 100 LL, 100-130 octane, or mogas is
available
• jet—
Jet A, Jet A-1 or Jet A+ fuel is available
• av/jet— Both av gas and jet fuel are available

3

Position— In degrees/minutes or degrees/minutes/seconds of latitude
and longitude.

4

5
Airport Position Page

1. Identifier (selectable)
2. Elevation
3. Fuel Availability
4. Airport Position
5. Approach Information
6. Controlled Airspace/Radar Capability
42

6

Approach Information— displays the airport approaches available
• no apr— No approach is available
• np-apr— Non-precision approach is available
• loc—
Localizer approach is available
• ils—
ILS approach is available
Controlled Airspace Information— displays controlled airspace type
• class B
• cta
• class C
• tma
Radar— displays approach/departure radar capability
• radar— indicates radar is present

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The airport communication page displays the radio frequencies and usage for
the selected airport, as well as sector and altitude restrictions.
To view the communication page from any of the airport information pages:
1. Rotate O with the cursor removed to display the communication page.

WPT KEY
Airport
Communications Page

SECTION

3

2. Rotate K in the direction of the arrow prompt to view additional frequencies. You may
also view additional frequencies with the cursor on the page by rotating the O knob.

The following descriptions and abbreviations are used on the communication page:
Frequencies without restriction information:
• ats - Automatic terminal information service (ATIS)
• ptx - Pre-taxi
• clr - Clearance delivery
• gnd - Ground
• twr - Tower
• uni - Unicom
• mul - Multicom
• atf - Aerodrome traffic frequency
• ctf - Common traffic advisory frequency (CTAF)
• mf - Mandatory frequency
• oth - Other frequencies
Frequencies with restriction information:
• dep - Departure
• apr - Approach
• arv - Arrival
• class B
• cta - ICAO control area • tma - ICAO terminal control area
• class C
• trsa - Terminal radar service area
‘Receive only’ frequencies will be followed by an ‘rx’ indicator, while ‘transmit
only’ frequencies will display a ‘tx’. If a frequency has sector and/or altitude restrictions, they will also be displayed. Sector restrictions define a range of radials from the
facility, while altitude restrictions may describe an area above, below or between
altitudes. Additional instructions, if available, will be displayed on the bottom line.

Airport communications page for KCLT. Note
the ‘rx’ (receive only) indication on the ATIS
frequencies.

Frequency page with sector restrictions.

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WPT KEY
Airport
Runway Page

The airport runway page displays runway designations, length, surface and
lighting for the selected airport, as well as ILS/localizer and/or pilot-controlled lighting frequencies.
To view the runway page from any of the airport information pages:
1. Rotate O with the cursor removed to display the runway page.
2. To view additional runway information, rotate K with the cursor removed.
The scrolling arrow prompt, located beside the identifier field, indicates which direction to
scroll for additional runway information.

If a localizer and/or ILS are used on the same runway, rotating K will sequence
through both sets of information.
Airport runway page for KICT.

The following descriptions and abbreviations are used on the airport runway
page:
Runway surfaces:
• hard - Hard (concrete, asphalt, etc.)
• seal - Sealed surface
• dirt - Dirt surface
• unkn -Unknown surface

• turf - Turf (grass)
• grav - Gravel surface
• soft - Unknown soft surface
• watr - Water landing site

Runway lighting:
To view additional runways, rotate the K knob in
the direction of the arrow prompts.

44

• pt lights - Part-time lights
• ft lights - Full-time lights
• pc Pilot-controlled (with frequency) lights
• no lights - No runway lighting

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VOR Information
The GNC 250XL features three VOR waypoint pages:
VOR identification— allows entry of desired VOR by identifier,
facility name or city; displays region and/or country of facility.

WPT KEY
VOR Information

SECTION

3

VOR position— allows entry of desired VOR by identifier; displays
latitude, longitude and frequency; provides magnetic variation, weather
broadcasts and DME/TACAN information.
VOR comments— allows entry of desired VOR by identifier; displays user
comments for the selected facility.
VOR information is accessed by entering the desired facility by identifier, city or
facility name (see page 39) on a VOR waypoint page. The VOR identification and
comments pages are identical in form and function to their airport page counterparts.

VOR identification page

To scroll through the VOR pages:
1. Make sure the cursor is not present. If it is, press C.
2. Rotate O in either direction to scroll through the available pages.

In addition to displaying the VOR frequency, magnetic variation and position, the
VOR position page indicates if a DME or TACAN is co-located at the facility. The ‘wx
bdcst’ field indicates that the VOR also transmits weather information.
VOR position page showing co-located TACAN
facility and weather broadcast.

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NDB Information

SECTION

3

WPT KEY
NDB Information

NDB Position Page

The GNC 250XL also uses identification, position and comments pages for NDB
information. The NDB waypoint pages are used in the same manner as VOR pages:
NDB information is accessed by entering the desired facility’s identifier, city or name
(see page 39) on the NDB identification page.
NDB identification page

To scroll through the NDB pages:
1. Make sure the cursor is not present. If it is, press C.
2. Rotate O in either direction to scroll through the available pages.

The NDB position page (see above) displays the selected facility’s identifier, frequency and position, as well as any weather broadcasts available. The NDB comment
page will display any user comments for the selected NDB (see page 54 for instructions on entering user comments).

NDB comments page

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Intersection Information

WPT KEY
Intersection
Information

SECTION

3

Intersection Position Page

The last database waypoint category available is intersections. Two intersection
pages are available: intersection position and intersection comments. Intersections
may be entered by identifier only (not city or name) on either intersection page.
To scroll through the intersection pages:

Intersection comments page

1. Make sure the cursor is not present. If it is, press C.
2. Rotate O to toggle between the available pages.

The intersection position page displays the selected facility’s identifier, region and/or
country, latitude and longitude, and the identifier, distance and bearing to the nearest
VOR (not necessarily the VOR used to define the intersection). The intersection comment page will display any user comments for the selected intersection (see page 54).

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User Waypoint Information

SECTION

3

WPT KEY
User Waypoints

In addition to the airport, VOR, NDB and intersection waypoints contained in your
NavData® card, the GNC 250XL allows you to store up to 1,000 user-defined waypoints. Once a user waypoint is created, two user waypoint pages will display the following information:
•
•
•
•

User waypoint page

Waypoint identifier
Position in latitude and longitude
Identifier, range and bearing from a reference waypoint
User comments

To scroll between the user waypoint position page and the user comments page,
rotate O. User waypoints may be created or modified using the W key. After selecting the waypoint identifier, as shown on page 39, you will be prompted to enter information if the waypoint is new. There are three ways to create a user waypoint’s position from the W key:
1. Enter the exact position of the new waypoint.
2. Reference a known waypoint by range and bearing.
3. Enter a range and bearing from your current position.
To create or edit a user waypoint:
1. Press W.

User waypoint comments page

2. Press C twice and use O to highlight the ‘user?’ field. Press E.
3. Use K and O to enter the waypoint identifier. Press E.

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If the waypoint identifier entered does not exist, you will be prompted to select a
method to enter the new waypoint’s position into memory. If the waypoint exists (i.e.,
you’re just reviewing or editing a user waypoint), skip step 4 and move on to the next
set of instructions.
4. Select the desired waypoint entry method using O and press E.

WPT KEY
Creating
User Waypoints

SECTION

3

You will automatically be placed on the latitude and longitude field (if you
selected ‘enter posn?’), the ‘from’ field (if you select ‘ref wpt?’) or the ‘bearing’ field (if
you select ‘rng/brg from posn?’).
To enter/edit the position of the user waypoint:
1. Use K and O to enter the latitude. You may select either north or south and enter a
latitude up to (but not including) 90°.

Selecting a method to enter a new user waypoint.

2. Press E.
3. Use K and O to enter the longitude. You may select either east or west and enter a
longitude up to (but not including) 180°.
4. Press E.

Once the latitude and longitude have been entered, the cursor will move to the
reference waypoint field,where you may enter a reference waypoint to calculate a
bearing and distance to the new waypoint position. If you are not entering a reference
waypoint:
5. Press E to advance the cursor to the ‘ok?’ prompt and press E to save the new
waypoint in internal memory.

Entering the user waypoint’s exact position.

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To enter/edit a user waypoint position from a reference waypoint:

SECTION

3

WPT KEY
Reference Waypoints

1. Use K and O to enter the reference waypoint’s identifier.
2. Press E. The waypoint’s position will appear.
3. Use K and O to enter the bearing from the reference waypoint.
4. Press E.
5. Use K and O to enter the distance from the reference waypoint.
6. Press E. The latitude and longitude will be calculated for the waypoint.
7. Press E to confirm the ‘ok?’ prompt and save the waypoint position.

Entering a user waypoint by referencing another
waypoint.

If you have chosen to create a waypoint at a certain bearing and distance from
your current position, your current position will be displayed and you will enter the
bearing and distance at which you would like the new waypoint to be located.
To create a user waypoint offset from your present position:
1. Use K and O to enter the bearing from your position.
2. Press E.
3. Use K and O to enter the distance from your position.
4. Press E. The latitude and longitude will be calculated for the new waypoint.

50

To create a user waypoint from your present position, leave the reference waypoint field blank and
enter a bearing and distance from your present
position. The GNC 250XL will calculate the new
waypoint’s coordinates automatically.

5. Press E to confirm the ‘ok?’ prompt and save the waypoint position.

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The GNC 250XL’s AutoStoreTM function provides another method of creating
user waypoints. AutoStore is used to instantly capture your present position as a user
waypoint with a touch of a button and add the new waypoint to the end of a specified
route if desired.

WPT KEY
Creating Waypoints
with AutoStore

SECTION

3

To perform an AutoStore:
1. Press N and rotate O to display the position page or map page.
2. Press E.

This will display the ‘Save waypoint’ screen, which will allow you to rename the
waypoint and choose the route to which it should be added. The GNC 250XL will
assign the next available three-digit number as the default waypoint name, preceded
by a ‘+’ sign. This will help you differentiate AutoStore waypoints from other user
waypoints.

AutoStore waypoint with default name.

To change the default name or route of an AutoStore waypoint:
1. Rotate O to select the name or route number field.
2. Use K and O to enter the name or route number. If you do not want to add the waypoint to a route, be sure to keep the route field blank.
3. Press E to accept.
4. Press E to confirm the ‘ok?’ prompt.

If the waypoint name you entered is already assigned to another waypoint, you
will be informed with the message ‘WPT exists ______’. The default waypoint name
will be redisplayed, and you may enter a different name.

The default waypoint name may be changed
before saving the waypoint.

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WPT KEY
Proximity Waypoints

The second page available from the GNC 250XL’s W key is the proximity
waypoints page. This page allows you to define an alarm circle around a selected
waypoint and is useful in defining alarm circles around towers or obstructions. Up to
nine proximity waypoints can be entered, each with an alarm radius of up to 99.9 nm.
To create or edit a proximity waypoint:
1. Press W and use O to display the ‘Proximity waypoints’ page.
2. Press C twice and use O to highlight the first available field.
3. Use K and O to enter the identifier. It may be an airport, VOR, NDB, intersection or user
waypoint. Press E.
4. Use K and O to enter the radius of the alarm circle. Press E.

Proximity waypoints page

If two proximity waypoints are entered and their regions overlap, you will be
informed with the message ‘Proximity overlap’. This message will be displayed each
time you turn on the GNC 250XL for as long as the overlap remains. Warning: If you
enter the overlap area you will only be informed of the nearest proximity waypoint.
To remove a waypoint from the proximity waypoints page:
1. Press C twice, if necessary, to obtain a cursor in the GPS window.
2. Press \ to erase the name, and then E to delete.
To scroll through the proximity waypoints list:

Proximity alarm message. Pressing N will
display the position page with the bearing and
distance from the proximity waypoint indicated
on the bottom line.

52

1. Rotate K with the cursor inactive (or use O with the cursor active) to scroll through the
available proximity waypoints. The scrolling arrow prompt will indicate the direction to
scroll to view additional waypoints, if available.

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The third page available from the GNC 250XL’s W key is the user waypoint
list, which can be used to quickly scan, review, rename or delete user waypoints.
To display the user waypoint list:
1. Press W and use O to display the user waypoint list.

WPT KEY
User Waypoint
List

SECTION

3

2. To scroll through the list, rotate K.

The total number of user waypoints is displayed at the top of the page, with the
individual user waypoints listed two at a time in alphabetical order below. The
scrolling arrow prompt, located at the top left of the page, will indicate which direction to scroll to view additional waypoints. The status of each waypoint will be displayed to the right of the identifier when it is the active-to waypoint, part of an active
or stored route or a proximity waypoint. To edit, rename or delete waypoints, the cursor must highlight the desired waypoint.
To highlight a waypoint:

User waypoint list showing the current active-to
waypoint and a proximity waypoint.

1. Press C twice and use O to highlight the desired waypoint.
To edit a highlighted waypoint’s position:
1. Press E to obtain the waypoint position page. Edit the waypoint position as described on
page 49. (Note: The active-to waypoint cannot be edited.)
To delete a waypoint from the list:
1. Highlight the desired waypoint and press \. Press E to confirm the deletion.
To rename a waypoint from the list:
1. Highlight the desired waypoint. Use K and O to enter a new
identifier for the waypoint.
2. Press E on the confirmation page to change the name, or press \ to cancel.

Renaming a user waypoint.

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WPT KEY
Waypoint Comments

The last page available through the GNC 250XL’s W key is the waypoints with
comments page, which lists all waypoints that have a user comment. User comments may be added to 250 waypoints stored in the user or NavData® database, and
allow you to note two lines of special information concerning a particular waypoint.
To enter user comments:
1. Enter the waypoint identifier from any waypoint page (see page 39), and press C to
remove the cursor.
2. Rotate O to display the ‘comments’ page.
3. Press C twice and use O to highlight either the second or third line.
4. Use K and O to enter the comment.

Entering waypoint comments.

5. Press E to accept, and repeat steps 4 and 5, if necessary, to enter information on the
other line.
6. Press C to remove the cursor.
To view the ‘waypoints with comments’ list:
1. Press W and use O to display the ‘Wpts with comments’ page.
2. Use K to scroll through the list.

The GNC 250XL will display the waypoints with comments in alphabetical order,
up to six waypoints at a time. The scrolling arrow prompt will indicate which direction to scroll to view additional waypoints.
Waypoints with comments page

To view comments for a selected waypoint:
1. Highlight the desired waypoint and press E (or press \ and E to delete).

54

2. Rotate O to display any other available pages for the selected waypoint.

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The GNC 250XL’s extensive waypoint database makes it possible for several waypoints to share the same identifier. To ensure that you are selecting the waypoint
desired, the GNC 250XL will always offer the waypoint confirmation page (which
shows the waypoint’s position) when an identifier is entered for a particular function.

WPT KEY
Waypoint Confirmation
Duplicate Waypoints

SECTION

3

To accept the waypoint position:
1. Press E with the cursor over the ‘ok?’ prompt.
To reject the waypoint position:
1. Press \ with the cursor over the ‘ok?’ prompt.

Once a waypoint has been accepted or rejected, the previous page will be displayed. If there is more than one waypoint available for a selected identifier, the GNC
250XL will display a duplicate waypoint page for you to choose the desired waypoint.
The waypoint identifier and number of duplicates will be shown at the top of the
page, with the waypoint type and region of each duplicate indicated below. The waypoints listed are sorted by the distance from your present position.

Waypoint confirmation page

To scroll through additional duplicate waypoints:
1. Rotate O with the cursor active, or K with the cursor inactive.
To select the desired waypoint from the duplicates list:
1. Activate the cursor and rotate O to highlight the desired waypoint.
2. Press E. The waypoint confirmation page will appear.
3. Press E over the ‘ok?’ prompt to accept the waypoint or \ to reject the waypoint
and return to the duplicate waypoints list.

Duplicate waypoints page

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WPT KEY
Locked Waypoints
Waypoint Scanning

Possible messages for locked waypoints.

Because the GNC 250XL relies on a NavData card for most waypoint information,
there may be instances when waypoint information is not available for use. Locked
waypoints exist when a waypoint contained in a route, used as a proximity waypoint
or with a comment is not contained on the NavData card, or no card is inserted in
the unit. If this condition exists, you’ll be alerted with a ‘Proximity wpt locked’,
‘Route wpt locked’ or ‘Wpt comment locked’ message when the unit is powered up.
The identifier of a locked waypoint will be replaced with a ‘lockd’ message, which
indicates you cannot obtain waypoint information or navigate to the waypoint. The
identifier of a locked waypoint may be displayed by highlighting ‘lockd’ and pressing
E. Locked waypoints may be deleted from routes, the proximity waypoints list or
waypoints with comments page by following the instructions in the appropriate
section of this manual.
The waypoint scanning feature provides a fast way to scan through airports,
VORs, NDBs and intersections in the database by identifier, facility name or city.
Waypoint scanning may be used from any blank identifier field in the GPS window.
To enter a waypoint by scanning the identifier, facility name or city:
1. With the cursor over a blank identifier field, press W. If the identifier field is not blank,
highlight the field with the cursor and press \ before pressing W.
2. Use O to highlight the waypoint category you wish to scan.
3. Press E to activate the scanning mode.
4. Rotate O to place the cursor over the field you want to scan (identifier, facility or city
name).

To blank a waypoint field, highlight the field and
press the \ key.

56

5. Use K and O to enter the letters of the identifier, city or facility name. The GNC 250XL
will scan the database and display the first waypoint that matches your entry.
6. Press E to accept the waypoint, and E again to confirm the waypoint for the
function being used.

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Section 4
Nearest Waypoints
The GNC 250XL’s T key provides detailed information on the nine nearest airports,
VORs, NDBs, intersections and user waypoints within 200 nm of your current position.
In addition, it will display the two nearest Flight Service Station (FSS) and center
(ARTCC/FIR) points of communication, plus alert you to any Special Use Airspace (SUA)
you may be in or near. The T key can be used in conjunction with the GNC 250XL’s
direct-to function to quickly set a course to a nearby facility in case of an in-flight emergency.

NRST KEY
Overview

SECTION

4

To view the nearest waypoint information:
1. Press T.

This will display the nearest airport to your present position, subject to the runway
surface type and minimum runway length selected (see page 79).
To scroll through the next eight nearest airports, rotate K.

Nearest airport with other frequency information.
If an airport has multiple frequencies available,
they may be quickly viewed without activating
the cursor by pressing the \ key repeatedly.

You may examine both the communication frequencies and the runway information
directly from the nearest airport page. You may also place the displayed frequency into
the standby field by pressing E from the nearest airport page.
To view more comm/runway information:
1. Press C twice and rotate O to highlight the comm field or the runway field.
2. Rotate K to scroll through more information, if available.
To perform a direct-to on any of the nearest waypoint pages:
1. Press D. The waypoint confirmation page will appear.
2. Press E to accept the waypoint or \ to cancel.

Nearest FSS page. To view additional frequencies
(if available), highlight the frequency and rotate
the O knob.

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NRST KEY
Special
Use Airspace

The nearest waypoints for other categories (VORs, NDBs, etc.) may be viewed
by rotating O. Rotating O continuously to the left will stop page selection on the
nearest airport category.
The next page available under the GNC 250XL’s T key is the SUA (special-use
airspace) alert page. The SUA alert page will alert you to as many as nine controlled or
restricted airspaces near or in your flight path, according to the following conditions:
• If your projected course will take you inside an SUA within the next 10
minutes, the message ‘SUA ahead < 10 min’ will be displayed.
• If you are within two nautical miles of an SUA and your current course will take
you inside, the message ‘SUA Near & Ahead’ will be displayed.

Nearest SUA

• If you are within two nautical miles of an SUA and your current course will not
take you inside, the message ‘Near SUA < 2nm’ will be displayed.
• If you have entered an SUA, the message ‘Inside SUA’ will be displayed.

Nearest SUA with controlling agency displayed.

58

NOTE: The GNC 250XL will flash the U next to the M key
to inform you of SUA alerts. You do not have to repeatedly
check the Nearest Waypoint page for SUA information. It is
provided to supply more information on the SUA and its
boundaries. The GNC 250XL will not flash alerts, however, if
it has been turned off or if your altitude is such that you will
not enter the buffered airspace. Turning off SUA alerts and
setting the altitude buffer is described on page 84.

Note that the GNC 250XL’s SUA alerts are based on 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. Once
you have met one of the described conditions, the message annunciator will flash, alerting you of an SUA message.
To view an SUA message:
1. Press the M key.
2. Press M again to return to the previous page.

Once you are notified of a SUA alert, detailed information concerning the specific
SUA is provided by the T key.

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To view the SUA alert page:

NRST KEY

1. Press the T key.

Special
Use Airspace

2. Rotate O one stop to the right to view the SUA alert page.

The SUA alert page contains the following information:
Alert type

SUA number

SUA Name or
controlling
agency
Controlling
airport identifier

SECTION

4

ETE
(if applicable)

SUA type

SUA Ceiling altitude

SUA Floor altitude

The ‘SUA number’ field displays which SUA you are viewing (you may be alerted to up
to nine SUAs). SUAs are ranked with ‘sua1’ being the highest priority, and ‘sua9’ being the
lowest priority from your current position. The ‘SUA alert’ field displays the corresponding
alert message for this SUA, such as ‘near’, ‘near & ahead’, etc. (see page 58). The ETE (estimated time enroute), located at the top right of the page, will only be displayed if you are
projected to enter the airspace.
The second line of the SUA alert page displays the name or controlling agency of the
SUA, along with the type of SUA to which you are being alerted.
To toggle between the SUA name and controlling agency display:
1. Rotate K one stop in either direction.

If the SUA name or controlling agency is too long to fit on the display, the GNC 250XL
will automatically scroll to display the rest of the information.

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The following SUA types can appear in the SUA type field:

SECTION

4

NRST KEY
SUA Messages

SUA alert page

Message
alrt
caut
cl B
cl C
cta
dngr
moa
proh
rstc
tma
trng
trsa
unsp
warn

Airspace Type
- Alert
- Caution
- Class B
- Class C
- ICAO Control Area
- Danger
- Military Operations Area
- Prohibited
- Restricted
- ICAO Terminal Control Area
- Training
- Terminal Radar Service Area
- Unspecified
- Warning

The last line on the SUA alert page displays the SUA’s controlling airport identifier
and the ceiling and floor altitudes for the SUA alert. Controlling agency frequencies
may be viewed by highlighting the controlling airport identifier with the cursor and
pressing E. The following are examples of what can appear in the altitude fields:

Frequency information for SUA. If the information is too long to fit on the display, the GNC
250XL will automatically scroll to display the rest
of the information.

60

Message
8000ftM
3000ftA
ground
msl
notam
not sp
unlmtd

Meaning
- 8000 feet mean sea level (MSL)
- 3000 feet above ground level (AGL)
- Ground level
- Mean sea level
- See Notice to Airmen (NOTAM)
for altitude restrictions
- Altitude is not specified
- Altitude is unlimited

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NRST KEY
Special Use
Airspace

SECTION

4

SUA Settings Page

All SUA alert messages except for prohibited areas may be turned on or off
through the GNC 250XL’s unit settings options, found under the M key (see page
84). Alerts for prohibited areas will always be displayed, regardless of unit settings or
operating mode. SUA alerts may be turned off so the pilot can avoid continuous alerts
in areas with extensive special use airspace.
Important: Turning off the SUA alerts only stops the display of SUA messages.
Any applicable SUA alert pages will still be available from the T key.

Altitude buffer set at 500 feet. This provides an
added 500 foot margin beyond the floor and ceiling limits for an airspace.

The GNC 250XL also features an altitude buffer which may be set to provide a
greater level of protection from penetrating an SUA. By specifying an altitude in the
buffer, you can effectively stretch an SUA’s altitude boundaries in both directions. This
allows the pilot to add an extra margin of prevention around controlled or restricted
airspace. For instructions on setting the altitude buffer, see page 84.

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DIRECT-TO
& ROUTE NAV

Section 5
Direct-to & Route Navigation
One of the many benefits of GPS navigation is the ability to fly directly to a waypoint or fly a chain of waypoints without using ground-based navigation aids. To take
advantage of the convenience and efficiency provided by point-to-point GPS navigation, the GNC 250XL provides two basic methods of selecting a destination for your
flight: direct-to and route navigation. The direct-to function provides a fast way to
set a course to a destination waypoint from your present position. The route function
allows the pilot to create a chain of waypoints to fly in sequence.
KSTL

ROUTE TERMINOLOGY
The diagram at the right shows a basic route
consisting of five waypoints and four legs.

MAP
'ACTIVE FROM' WAYPOINT

The waypoint you are travelling to is called the
‘active to’ waypoint, and the waypoint immediately
behind you is called the ‘active from’ waypoint. The
course line between the active from and the active to
waypoint is called the ‘active leg’.

'ACTIVE TO' WAYPOINT

SGF
ACTIVE LEG
EOS

KTUL

As you pass each waypoint in the route, the GNC 250XL’s automatic leg sequencing and turn anticipation features will automatically select the next waypoint as the
‘active to’ waypoint and provide smooth steering guidance around the turn. If you are
not currently navigating a particular route leg (e.g., your starting position is not a
route waypoint), the GPS will select the appropriate leg as the active route segment.
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The GNC 250XL’s direct-to function provides a quick method of setting a course
to a destination waypoint. Once a direct-to destination is activated, the GNC 250XL
will establish a point-to-point route line along the great circle from your present
position to the destination and provide steering guidance and navigation data to the
waypoint until it is cancelled. If you are navigating to a waypoint and get off course,
the direct-to function may also be used to re-center the d-bar to proceed to the same
waypoint.

DIRECT-TO
Selecting and
Cancelling a Direct-To

SECTION

5

To select a direct-to destination:
1. Press the D key. The CDI page will appear with the destination field highlighted.
2. Use K and O to enter the identifier of the desired waypoint.
3. Press E to confirm the identifier, and E to accept the direct-to confirmation page.
To re-center the d-bar to the same active-to waypoint:
1. Press the D key, followed by E twice.

To select a direct-to destination, press the D key
and enter the waypoint identifier using K and O.

A direct-to may also be quickly activated from many pages that display a single
waypoint identifier (e.g., the nearest airport page) by simply pressing D and E.
For pages that display a list of waypoints (e.g., the user waypoint list page), you must
highlight the desired waypoint with the cursor before pressing the D key. Once a
direct-to is activated, the GNC 250XL will provide navigation guidance until the
direct-to is cancelled or the unit is turned off.
To cancel a direct-to destination:
1. Place the cursor over the destination field on the CDI page.
2. Press \. The destination field will go blank.
3. Press E. The GNC 250XL will resume navigating route 0 (the active route) if available.

To quickly select a direct-to from any page that
displays a single waypoint identifier (e.g., the
nearest airport page), press D, followed by E.

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DIRECT-TO
Manually Selecting
A Course

Whenever you perform a direct-to, the GNC 250XL will set a point-to-point great
circle course to your destination. You can also manually define the course to your
destination with the GNC 250XL’s course select feature. The course select feature is
available from the bottom line of the direct-to confirmation page and works like
selecting your desired course on a VOR indicator.
Waypoint Position, Facility
Name or City/Region
(selectable)

The waypoint sequencing field, located at the
bottom left of the direct-to confirmation page,
allows you to ‘hold’ on a selected route waypoint
and prevent the GNC 250XL from sequencing to
the next route waypoint.
If you have selected the ‘hold’ setting from the
waypoint sequencing field, your selected course
will appear at the bottom left of the CDI page and
the map page. You may change your selected
course right from this field by highlighting the
course field and rotating the inner knob. Press E
to confirm the course.

64

Waypoint Identifier Field

Waypoint
Sequencing Field
Course Select Field

To manually set a course:
1. Press the D key. The direct-to confirmation page will appear.
2. Rotate O to place the cursor on the course select field.
3. Use K to begin entry of the selected course (the O and K knobs may be used once
you have started editing the course select field).
4. Press E to accept the course, and E again to acknowledge the ‘ok?’ prompt.

The GNC 250XL will now use the selected course for your CDI and DTK steering
guidance. To reset the course to a GPS-calculated course from your present position,
simply press D, followed by E.

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The GNC 250XL lets you create up to 20 routes (numbered 0 through 19), with
up to 31 waypoints each. Routes are created, copied and edited through the R key,
which features two route pages selectable from the GNC 250XL’s outer knob: the
active route page and the route catalog page. The active route page provides information and editing functions for route 0, which always serves as the route you are
currently navigating. The route catalog page serves as the main page for creating, editing, activating, deleting and copying all routes.

ROUTES
Overview
Route Catalog Page

Routes 1-19 are used as storage routes, which are stored in the GNC 250XL’s internal memory. Once a storage route is ‘activated’, it is placed into route 0 for navigation
until it is cancelled, overwritten by activating another route or erased when the GPS is
turned off. If you want to save a route currently in route 0, be sure to copy it to an
open storage route (routes 1-19) before it is cancelled, overwritten or erased.

To add user comments to any route (except route 0):
1. Rotate K to display the route you would like to add comments to.
2. Press C twice and use O to highlight the bottom row.
3. Use K and O to enter comments, and press E. To erase press \, then E.

5

2

{

The GNC 250XL’s route catalog page is used to create, edit, delete or copy
routes, and serves as the main page for a host of functions. These include route activation, determining the closest point of approach and search and rescue operations. It
also displays a summary of routes currently stored in memory, with the departure and
arrival route waypoints and total distance for the selected route number. To scroll
through the available routes, rotate K. A one-line user comment may be added to
any storage route, which will be displayed on the route catalog page.

1

SECTION

3

5

4

Route Catalog Page

1. Route selection field
2. Route action field
3. Departure/Arrival waypoints
4. Cumulative distance of route
5. Comments/Parallel track offset field

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ROUTES
Creating &
Editing Routes

The route action field, located at the top right of the page, is used to select the
desired route operation. The following functions are available:
•
•
•
•
•
•
•

Activate Reverse Edit Delete Copy CPA Search -

activate the route for navigation
activate a route in reverse order
create a new route, or edit an existing route
delete a route
copy the current route to an empty route
calculate the closest point of approach
perform search and rescue ladder operations

The route editing function allows you to create new routes and edit existing routes.
Creating routes before takeoff can help make route operations faster and easier during
your flight.
Selecting the route edit function.

To create or edit a route from the route catalog page:
1. Use K to display the route number you would like to edit.
2. Press C twice.
3. Use K to select ‘edit?’. Press E. The route review page will appear.
To add a waypoint:
4. Rotate O to highlight the first blank waypoint field or the point where you want to enter the
new waypoint. The first waypoint field will already be highlighted if you’re creating a new route.
5. Use K and O to enter the waypoint’s identifier. Press E.

Adding a waypoint to route 2.

6. Press E to confirm the ‘ok?’ prompt on the waypoint confirmation page.
7. Repeat steps 4 through 6 to add the next waypoint, or press C to finish.

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To delete a waypoint:
1. Rotate O to highlight the waypoint you wish to delete.
2. Press \ to remove the name, then press E to delete.
3. Repeat steps 1 and 2 to delete additional waypoints, or press C to finish.

ROUTES
Deleting &
Activating Routes

SECTION

5

To delete an entire route:
1. Use K to display the route number you would like to delete (route 0 for the active route).
2. Press C twice and use O to highlight the action field.
3. Use K to select ‘delete?’. Press E to delete.

Once a route is defined through the route catalog page, it may be activated from
the route catalog page. Activating or reversing a route places the selected route into
route 0 and overwrites the existing active route.

Deleting route 0.

To activate a route:
1. Press R and use O to display the route catalog page.
2. Rotate K to display the route you would like to activate.
3. Press C twice and use K to display ‘activate?’. Press E.

After travelling a route or creating a route with the GNC 250XL’s AutoStore feature,
the route activation field may be used to activate the route in reverse order.
To activate a route in reverse order:
1. Press R and use O to display the route catalog page.

Reversing route 0.

2. Use K to display the route number you would like to reverse.
3. Press C twice and use K to display ‘reverse?’. Press E.

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ROUTES
Copying Routes
CPA Function

The route action field also features a copy function that permits you to copy any
route to another open storage route. The copy function can be used to save the contents of the active route (route 0) to an open storage route.
To copy a route:
1. Press R and use O to display the route catalog page.
2. Use K to display the route to which you would like to copy to. The route must be empty.
3. Press C twice and rotate K to select ‘copy?’. Press E.
4. Use K to enter the route you would like to copy. The departure/arrival identifiers will be
displayed for your reference. Press E to copy the route.

Calculating closest point of approach.

The CPA function calculates the closest distance that a route will pass to a reference waypoint, and helps when creating new route waypoints referenced to a NAVAID.
To calculate the closest point of approach (CPA) from the route catalog page:
1. Use K to display the route you would like to use for the CPA function. The route must
consist of at least two waypoints, and the reference facility must fall between the
waypoints of a route leg.
2. Press C twice and rotate K to select ‘cpa?’. Press E.
3. Use K and O to enter the identifier of the reference waypoint.
4. Press E. The bearing and distance of the closest point on the route will be displayed.

Closest point of approach to ‘TXK’.

68

5. Press E to add the cpa waypoint to the route, or \ to finish. If you do add the cpa
waypoint to the route, it will be named based on the reference waypoint plus a number (09) added to the end (e.g., KMCI3 for KMCI). If the waypoint does not fall between waypoints
on the route, the reference waypoint does not exist or a unique name cannot be assigned to
the CPA waypoint, you’ll be informed with the ‘Invald CPA wpt ____’ message.

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The GNC 250XL’s search and rescue function provides navigation guidance for
search and rescue operations, navigating in a ladder pattern to maximize coverage and
efficiency. This is done in reference to two waypoints called ‘anchor waypoints’. The
first leg will be a specified distance from the line connecting the anchor waypoints.
This is called the ‘offset distance’. The ‘increment distance’ is the distance between each
subsequent leg. The ladder can be created on either side of the anchor waypoints.

ROUTES
Search & Rescue
Operations

SECTION

5

To perform a search and rescue operation:
1. Create a route of only two waypoints.
2. Press R and use O to display the route catalog page.
3. Use K to select the 2-waypoint route.
4. Press C twice and use K to display ‘search?’. Press E.
5. Use K and O to enter the leg increment value and R or L. Press E.
6. Rotate O to highlight the initial offset, and use K and O to enter the initial offset
value, and R or L.
7. Press E three times to accept the operation values and begin navigation.

After activating a search and rescue, you will be informed with an ‘Offset nav in
effect’ message each time you traverse the route offset from the anchor waypoints and
the CDI page will guide you along each leg of the ladder pattern. Note that bearing
and distance information are referenced to the anchor waypoints. Once you’ve arrived
at the destination waypoint, the leg increment will be added to your present offset, and
the route will be automatically reversed. If a search and rescue is interrupted, note the
parallel track direction (R or L) and distance on the catalog page for route 0. When
you resume search and rescue operations, use this as the initial offset.

The map page will show the active leg of the
search and rescue pattern as a solid line with the
anchor waypoints joined together by a dashed line.

Performing a search and rescue operation.

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ROUTES
Parallel Track
Offset Navigation
Enter parallel track value after route activation.

During route navigation, it is sometimes desirable to navigate a specified distance
away from the ‘active leg’ to help avoid certain airspaces or regions. The GNC 250XL’s
parallel track feature will automatically guide you along a selected offset from the
active leg. Bearing and distance information will be to the waypoints along the original course, with the CDI (on the CDI page) centered on the offset course line.
To use offset navigation, or ‘parallel track’:
1. Press R and use O to display the route catalog page.
2. Use K to display route 0 (parallel track can only be used on the active route).
3. Press C twice and use O to highlight the parallel track value field.
4. Use K and O to enter the desired distance and direction (R or L) from the leg.

Parallel Track

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5. Press E to accept. The map page will display the offset route as a solid line and the
original route as a dashed line.

It is important to note that offset navigation is only available on route navigation,
not direct-to navigation. When offset navigation is activated, an ‘Offset nav in effect’
message will be displayed with the distance and direction noted on the route catalog
page for route 0. If you enter an offset which causes a leg to be reversed, you’ll be
informed with the message ‘Ofst too big for rte’. If you change the active route in any
way or perform a direct-to, you’ll be informed with an ‘Offset nav cancelled’ message.

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Flying and Modifying the Active Route
Once a route has been created and activated, the GNC 250XL will provide navigation to each route waypoint through the active route and CDI pages. From the active
route page, you may also create and modify the active route. The CDI page will display detailed navigation data on your progress to each route waypoint and provide
turn anticipation, waypoint arrival and next desired track information. By understanding the relationship between the active route and CDI pages and the role of the
waypoint sequencing selector, you’ll be able to get the most out of the GNC 250XL’s
advanced route features.
Whenever the GNC 250XL is navigating an on-route direct-to or route, the active
route page will provide a list of the route waypoints in sequence, along with distance, time and course information. You may also create and edit a route directly from
the active route page. If you want to save a route created from the active route page
(route 0), you must copy it to an open storage route (see page 68) before turning the
unit off or activating another route. The active route page may be displayed by pressing the R key and rotating O left continuously. It will also appear whenever a
route is activated.
To scroll through the active route waypoints:
1. Rotate K with the cursor inactive (or O with the cursor active).

The active leg identifiers field, located at the top left of the page, displays the waypoint identifiers of the route leg you are currently navigating. The first waypoint identifier displayed is the ‘active from’ waypoint. The second waypoint is the ‘active to’
waypoint. The line connecting these waypoints is known as the ‘active leg’. If you are
navigating a direct-to, the field will display the destination with a ‘goto’ designation.

ROUTES

SECTION

Active Route Page

5

USING THE ACTIVE ROUTE PAGE
The GNC 250XL’s active route page provides a
working list for the route you are navigating,
allowing you to view all route waypoints, along
with distance, timing or desired track information.
The scrolling arrow prompt to the left of the route
waypoint list indicates which way to scroll to
view additional route waypoints.
The active route page can also be used to manually select your next ‘active-to’ destination using
D, which allows you to fly directly to any waypoint in the route without modifying the route
itself. The GNC 250XL will resume navigation of
the remainder of the route in sequence once you
arrive at the selected waypoint.

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ROUTES
Active Route Page
Inserting Waypoints

The leg field can be selected to display cumulative distance or the distance for each
route leg. If cumulative is selected, the first leg’s distance will be displayed. The second
leg will represent the first leg’s distance plus the second leg, and so on. The time field
may be configured to display the estimated time enroute (ete), estimated time of arrival
(eta) or desired track (dtk) for each leg.
To change the leg and time fields:
1. With the cursor active, rotate O to highlight the field you want to change.
2. Rotate K to select the desired setting and press C.

Active route page with cumulative distance (cum)
and desired track (dtk) displayed.

The active route page may also be used to create a new route or edit the route you
are currently navigating, and provides a fast method of selecting any route waypoint as
your next destination waypoint without modifying the active route. If you are editing
the active route and want to save it in its original form, copy it to an open storage route
before editing.
To add waypoints to the active route:
1. Press C twice, if necessary, to activate the cursor.
2. Use O to highlight the first blank waypoint field, or highlight the waypoint before which
you would like to add the new waypoint.
3. Use K and O to enter the new waypoint identifier. Press E.

Active route page with leg distance and estimated
time enroute displayed.

72

4. Press E to accept or \ to cancel. The cursor will automatically move to the next
waypoint field, and the remaining route waypoints (if any are present) will move down the
list accordingly.

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To delete a waypoint from the active route:
1. Press C twice, if necessary, to activate the cursor.
2. Use O to highlight the waypoint you would like to delete from the active route.
3. Press \, followed by E. The next route waypoint (if available) will move up to take
the position of the deleted waypoint.

ROUTES
On-Route Direct-To
Waypoint Sequencing

SECTION

5

The active route page also allows you to select your next destination waypoint
manually from the active route waypoint list and resume the remainder of the route in
sequence. This procedure, referred to as an ‘on-route’ direct-to, allows the pilot to
fly directly to any waypoint in the active route without editing the active route itself.
To perform an on-route direct-to from the active route page:
1. Press C twice and rotate O to highlight the desired waypoint.

You can hold on a destination waypoint by setting
the waypoint sequencing field to the ‘hold’ position. A user-defined course may also be entered in
the course select field.

2. Press D, followed by E to confirm the ‘ok?’ prompt on the waypoint
confirmation page.

The GNC 250XL will now provide guidance to the selected waypoint and resume
navigating the remainder of the route in sequence once you arrive at the next destination waypoint. The waypoint sequencing field, located at the bottom left of the
direct-to confirmation page, allows you to select manual or automatic waypoint
sequencing of route waypoints. Setting the selector to the ‘hold’ setting holds your
current ‘active-to’ waypoint as your navigation reference and prevents the GPS from
sequencing to the next waypoint in the route. The waypoint sequencing selector may
be used in conjunction with the course select feature (see page 64) to manually select
the course to the ‘hold’ waypoint.

Whenever waypoint sequencing is set to ‘hold’, the
desired course is displayed at the bottom left of the
CDI page. See page 64 for more details.

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ROUTES
Waypoint
Sequencing

To ‘hold’ on the active-to waypoint:
1. Press D and E. The direct-to confirmation page will appear.
2. Rotate O to highlight the waypoint sequencing field, and rotate K to select ‘hold’.
3. Press E. The cursor will advance to the course select field where you may manually
enter the desired course to the ‘hold’ waypoint. The default course is the GPS course calculated from your present position.
4. Press E to accept the course select field.
5. Press E to confirm the ‘ok?’ prompt. The map page will display the inbound course as
a solid line and the outbound course as a dashed line.

As you approach a route waypoint, the graphical
CDI will be replaced by a flashing ‘Next dtk xxxº’
prompt indicating the desired track of the next leg.
When using the map page, the desired track readout will flash and indicate the dtk for the next leg.

74

If the turn angle and your present speed will
require a bank angle that exceeds 25º, you’ll be
notified with a ‘Steep turn ahead’ message
approximately 90 seconds before arrival at the
active to waypoint.

During route operations, the CDI page is used to provide turn anticipation, next
desired track and waypoint arrival information to the pilot. The GNC 250XL’s turn
anticipation feature will smooth out the transition between adjacent route legs by
providing CDI guidance along a curved path segment. This leg transition is based on
the aircraft’s actual ground speed and the difference between the course angle of the
two legs. The GNC 250XL will automatically sequence to the next leg when you are
abeam the ‘active to’ waypoint on the curved transition segment, and the to/from
indicator on the CDI will flip momentarily. During the transition, the CDI display will
be referenced to the dotted line illustrated at the left of this page. As you approach a
route waypoint, the graphical CDI on the CDI page will be replaced by a flashing
‘Next dtk xxxº’ prompt and the desired track readout on the map page will flash,
both indicating the desired track of the next route leg.
Turn anticipation will not be provided if you have set the waypoint sequencing
field to ‘hold’ or your current ground speed and the course angle between the two
legs would require a bank angle greater than 25º. If the leg transition is too short for
a smooth transition, a ‘Leg not smoothed’ message will appear, and the pilot should
expect a rapid change in the CDI deflection.

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Section 6
Messages and Unit Settings
The GNC 250XL’s M key provides access to system messages and allows you to
customize the unit to your own preferences through a settings submenu. Whenever the
GNC 250XL needs to alert you to a navigation, communication or system message, the
annunciator light (U) next to the M key will flash. Some messages are advisory in
nature (e.g., the arrival and countdown alarms), while others may require your immediate attention (e.g., a stuck microphone message). For a complete list of GNC 250XL
messages, please see Appendix D.
To view a message, press M. Press M again to return to the previous page.

UNIT SETTINGS
Messages &
Settings Submenus

SECTION

6

To view a message, press M.

The GNC 250XL’s settings submenu is also accessed from the M key.
To view the settings submenu, press and hold M for more than 2 seconds.
Once the settings submenu has been accessed, the following setup pages are available
by rotating O with the cursor inactive:
•
•
•
•
•
•

Map page settings
Nearest airport search
Battery saver
Backlighting settings
Navigation units
Map datums

•
•
•
•
•
•

CDI scale settings
Mag. var./arrival alarm settings
Display screen settings
Trip timer settings
SUA settings
I/O Settings (channel 2 only)

To access the settings submenu pages, press and
hold the M key for two seconds. The GNC
250XL will return to the last submenu viewed the
next time you access the unit settings.

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UNIT SETTINGS
Map Page Setup

The GNC 250XL’s map page is designed to be a flexible tool that can be customtailored to your navigation needs. The map setup page provides access to many of
the features and functions that will help you configure the map page to your own
preferences. From the map setup page you can set the map orientation, automatic
zoom, and specify which waypoints and airspace boundaries you wish to display.
The map orientation setting allows you to orient the top of the map display to
your current ground track (‘trk up’), fix the top of the map to north like a paper chart
(‘nrth up’) or set the top of the map along your desired track (‘dtk up’).
To change the map orientation:
1. Press and hold M, then rotate O to select the ‘MAP Setup’ page.

Map Setup Page

2. Press C twice to highlight the orientation field.
3. Rotate K to select ‘trk up’, ‘dtk up’ or ‘nrth up’.

The automatic zoom feature will automatically adjust the map display scale during your flight. Starting at an en route scale of 300 (nautical miles, statute miles or
kilometers) the scale will adjust through each lower scale, stopping at a scale of 1 as
you approach your destination waypoint.
To turn the automatic zoom feature on or off:
1. Press and hold M, then rotate O to select the ‘MAP Setup’ page.
The map orientation may be set to north up, track
up or desired track up. This determines what
direction the top of the map display is oriented to.

76

2. Press C twice and rotate O to highlight the ‘auto zoom’ field.
3. Rotate K to select ‘on’ or ‘off’.

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The map setup page also allows you to control whether or not the various waypoint types and the identifiers for these waypoints are displayed. Settings for each
waypoint type allow you to select the maximum scale at which that feature should be
displayed, or you may turn that waypoint type off for all scales. For example, by setting ‘VOR’ at 80, VOR waypoints will appear on the map display at all scales from 80
on down, but not at 120, 200 or 300.

UNIT SETTINGS
Map Page Setup

SECTION

6

To display airports, navaids and/or user waypoints:
1. Press and hold M, then rotate O to display the ‘MAP Setup’ page.
2. Press C twice and rotate O to highlight ‘apt’, ‘vor’, ‘ndb’, ‘int’ or ‘user’.
3. Rotate K to select the maximum map scale for that waypoint type, or select ‘off’ to disable the waypoint type entirely.
To display waypoint identifiers:
1. Press and hold M, then rotate O to display the ‘MAP Setup’ page.
2. Press C twice and rotate O to highlight ‘apt ident’, ‘vor ident’, ‘ndb ident’, ‘int ident’,
or ‘user ident’.

The automatic zoom feature will automatically
adjust the map display through progressively
lower scale settings as you approach your
destination waypoint.

3. Rotate K to select the maximum map scale for that waypoint category, or select ‘off’ to
disable the waypoint identifiers.

The boundaries for airspaces that appear on the map display may be enabled or
disabled by airspace type. As described above for waypoints, you select the maximum scale at which the airspace should appear or turn the airspace type off entirely.
Airspace categories for Class B/CTA, Class C/TMA, MOA, restricted and other SUAs
are provided. ‘Other sua’ includes alert, caution, danger, training and warning areas.

A scale setting of ‘200’ for airports will display
airport locations on the map display for all scales
from ‘200’ on down. Airports will not appear on
the map display at a scale setting of ‘300’.

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To enable/disable airspace boundaries on the map:

SECTION

6

UNIT SETTINGS

1. Press and hold M, then rotate O to select the ‘MAP Setup’ page.

Map Page Setup
CDI Settings

2. Press C twice and rotate O to highlight ‘class B/cta’, ‘class C/tma’, ‘moa’,
‘restricted’ or ‘other sua’.
3. Rotate K to select the maximum map scale for the designated airspace type, or select
‘off’ to never display.

The next page under the settings submenu is the CDI settings page, which
allows you to define the scale of the GNC 250XL’s course deviation indicator.
To change the CDI scale:
1. Press and hold M, and rotate O to select the ‘CDI Settings’ page.
When the ‘auto’ CDI setting is selected, the
GNC 250XL will automatically change the CDI
scale when you are within 30 nm of a departure
or arrival airport.

The ‘auto mag’ setting will automatically calculate
the magnetic variation based upon your current
position.

78

2. Press C twice and rotate K to select ‘Auto’, ‘+- 5.0 nm’, ‘+- 1.0 nm’ or ‘+- 0.3 nm’.
3. Rotate O to highlight ‘ok?’ and press E to approve.
(Note: the selected CDI scale will not take effect until approved.)

The scale values represent full scale deflection of the CDI to either side. The
default setting is +- 5.0 nm. The ‘Auto’ setting will start the CDI scale at 5 nm (en
route), and gradually ramp down the scale to the 1 nm range once you are within 30
nm of a departure or arrival airport (terminal area). For auto CDI scaling to occur,
you must have an active direct-to or route with an airport as your final destination
waypoint, or be within 30 nm of a departure airport. Note that the GNC 250XL uses
Receiver Autonomous Integrity Monitoring (RAIM) to cross-check its position.
The RAIM protection limits listed below follow the selected CDI scale, changing automatically with the ‘Auto’ setting:
CDI Scale
RAIM Protection
+/-5.0 nm or Auto (en route)
2.0 nm
+/- 1.0 nm or Auto (terminal)
1.0 nm
+/- 0.3 nm
0.3 nm

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The GNC 250XL has three magnetic variation options: true, auto, or user-defined.
To set the magnetic variation:
1. Press and hold M, and use O to display the ‘Mag Var/Arvl Alarm’ page.
2. Press C twice and use K to select ‘auto mag’, ‘true hdg’ or ‘user mag’.

UNIT SETTINGS
Magnetic Variation
Arrival Alarm

SECTION

6

3. If user is selected, use O to highlight the magnetic variation value, and use K and O to
enter the value and ‘E’ or ‘W’. Press C to finish.

If ‘auto’ mag var is selected, all track, course and heading information will be corrected
to the magnetic variation computed by the GPS. The ‘true’ setting will reference all information to true north, and the ‘user’ setting will correct information to an entered value.
The GNC 250XL’s arrival alarm can be set to notify the pilot with a message when
you have reached a user defined distance to a final destination waypoint (the direct-to
waypoint or the last waypoint in a route). Once you have reached the set distance (up to
99.9 units), an ‘Arrival at _____’ message will be displayed.

Setting the arrival alarm to 10 nautical miles.

To set the arrival alarm distance:
1. Press and hold M, and use O to display the ‘Mag Var/Arvl Alarm’ page.
2. Press C twice and use O to select the arrival distance field.
3. Use K and O to enter the desired distance. Press C to finish.

The nearest airport search settings allow you to define the runway length and
surface type used in determining the nine nearest airports displayed. A minimum runway
length and surface type may be entered to prevent airports with small runways, or runways that are not of appropriate surface, from being displayed. The default settings are ‘0
ft/mt’ for runway length and ‘any’ for runway surface type.

The runway length and surface type settings allow
pilots of large, high-performance aircraft to direct
the T key function to ignore those airports at
which if would be difficult, if not impossible, to
land their aircraft.

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To set the minimum runway length and runway surface:

SECTION

6

UNIT SETTINGS
Nearest Airport Search
Battery Saver

1. Press and hold M and use O to display the ‘Nearest apt search’ page.
2. Press C twice and use K and O to enter the minimum runway length upon which
your aircraft can land (up to 9999 units). Press E to accept the distance.
3. Rotate K to display the surface selection you desire. Choices include:
• any surface
• soft/hard surface

• hard only surface
• water only surface

4. Use O to select ‘ok?’ and press E to confirm.

Display timeout settings. As shown, the display
backlight will turn off after 30 seconds to conserve
power in the optional battery pack.

The GNC 250XL’s battery saver feature can be programmed to automatically
turn off the backlighting when using the optional remote battery pack. This will
increase the remote battery life in the event of power failure. During this time, the
GNC 250XL will continue to navigate and track satellites, but will not backlight the
display until a key is pressed or a knob is turned.
To set the display timeout:
1. Press and hold M and rotate O to display the ‘Battery saver’ page.
2. Press C twice to activate the cursor.
3. Rotate K until the desired value is displayed (0, 30, 60 or 90 seconds). Entering 0 will
leave the display on at all times. Press C to finish.

80

The GNC 250XL features automatic contrast and backlighting control to adjust
the display for optimum viewing in any condition. This is done using a photocell at
the top left corner of the display bezel. It is important that this photocell not be covered to ensure proper display adjustment. You may also select manual control of the
display contrast and backlighting to tailor the GNC 250XL to your needs.

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To change the display contrast settings:
1. Press and hold M and rotate O to show the ‘Display’ page.

UNIT SETTINGS

2. Press C twice and use K to select ‘auto’ or ‘manual’ control.

Display Settings

3. Press E.

SECTION

6

4. If ‘manual’ is selected, use K to set the display constrast level. (If ‘auto’ is selected you may
also change the offset level to your preference.)
5. Press C to complete.

The ‘mode’ selection allows you to display on-screen characters as black on a light
green background (positive) or light green on a black background (negative). With the
‘auto’ setting the photocell selects the best mode for day or night viewing.
To change the display mode settings:
1. Press and hold M, and rotate O to show the ‘Display’ settings page.

The display contrast may be set to automatically
adjust to varying lighting conditions, using the
built-in photocell.

2. Press C twice and use O to highlight the ‘mode’ field.
3. Rotate K to select ‘pstv’, ‘ngtv’ or ‘auto’.
4. If ‘auto’ is selected, rotate O to highlight the threshold level, and use K to select the level
at which the display will switch from positive to negative for night time use. (Note: Some
experimentation may be necessary to obtain the desired response level.)

The backlight intensity settings control the backlighting level and allow for automatic
adjustment using the built-in photocell or manual adjustment.
Setting the display mode to ‘negative’ will display
on-screen characters as light green on a black
background. This setting is suitable for night time
operation.

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UNIT SETTINGS
Backlighting
Trip Timer

To change the backlighting intensity:
1. Press and hold M, and rotate O to display the ‘Backlight intensity’ page.
2. Press C twice to highlight the ‘mode’ field.
3. Rotate K to select ‘auto’ or ‘manual’.
4. If ‘manual’ is selected, rotate O to highlight the ‘level’ field, and use K to select the
desired backlighting level.

The trip timer provides a running clock on NAV Menu 2 (see page 29), and can
be configured to run when power is on or when your ground speed exceeds a userdefined minimum.
To change the trip timer settings:
The backlight intensity settings page is used to
set/adjust the screen backlighting for day or night
time operation.

1. Press and hold M, and use O to display the trip timer settings page.
2. Press C twice to activate the cursor.
3. Use K to select either ‘pwr is on’ or ‘gs exceeds’.
4. If you choose ‘pwr is on’, press C to complete.
5. If you choose ‘gs exceeds’, use O to highlight the speed field.
6. Enter the speed using K and O.
7. Press E to accept, and press C to complete.

Trip timer settings, showing timer active when
groundspeed exceeds 100 knots.

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The GNC 250XL can be configured to display data in standard or metric units of
measure. These apply to: distance, position, speed, altitude, fuel, pressure and
temperature.

UNIT SETTINGS

SECTION

Units of Measure

To change the units of measure:

6

1. Press and hold M and rotate O to display the nav units page.
2. Press C twice and rotate O to highlight the field you would like to change.
3. Use K to change the unit of measure.
4. Rotate O to advance to the next field, or press C when finished.

The available units of measure are:
position :

• degrees, minutes and seconds (dms) [hddd° mm’ ss.s”]
• degrees and minutes (dm) [hddd° mm.mmm’]

altitude :

• feet (ft)

vertical speed : • feet per minute (fpm)
• meters per second (mps)

• meters (mt)
• meters per minute (mpm)

nav units :

• nautical miles and knots (nm, kt)
• statute miles and miles per hour (mi, mh)
• kilometers and kilometers per hour (km, kh)

fuel :

• gallons (gl)
• kilograms (kg)
• liters (lt)

• imperial gallons (ig)
• pounds (lb)

• inches of mercury (hg)

• millibars (mb)

pressure :

temperature : • degrees Fahrenheit (°f)

Default units of measure settings.

• degrees Celsius (°c)

Units of measure settings with all metric values
displayed.

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UNIT SETTINGS
SUA Settings
Altitude Buffer

The SUA settings page with all airspace alerts
enabled and the altitude buffer set to 100 meters.

The Special Use Airspace settings page will allow you to turn the controlled/
restricted airspace message alerts on or off. This will not affect the alerts listed on the
nearest page. It will simply turn off the warning when you are approaching or near an
SUA. Warnings can be turned on/off for the following airspaces:
class B/cta : ICAO control area
class C/tma : ICAO Terminal Control Area
rstcd:
Restricted areas

moa: Military operations area
other: Other areas includes: alert,
caution, danger, training, warning

SUA warnings for prohibited airspace cannot be turned off. The ‘alt’ field,
located at the bottom of the SUA settings page, is an altitude buffer which ‘expands’
the vertical range of the SUA, so you will be notified if you are within a certain range
of an SUA. For example, if the buffer is set at 500 feet, and you are more than 500 feet
above or below an SUA, you will not be notified with an alert message; if you are less
than 500 feet above or below an SUA and projected to enter it, you will be notified
with an alert message. The default setting for the altitude buffer is 200 feet.
To set the warnings or change the altitude buffer:
1. Press and hold M, and use O to display the SUA settings page.
2. Press C twice.
3. Rotate O to highlight the field you would like to change.
4. Use K to change to ‘on’ or ‘off’.

The SUA settings page with ‘other’ airspaces disabled and the altitude buffer set to 500 feet.

84

5. To change the altitude buffer, highlight the buffer value, and use K and O to change the
data. Press E to accept.
6. Press C to complete.

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The NavData card contains over 100 map datums for you to use when navigating.
By default, your unit calculates positions using the WGS 84 map datum. If you are
using charts based on another datum, you must set the GNC 250XL to use the same
datum. Using a map datum that does not match the charts you are using can result in
significant differences in position information. If you are using maps for reference
only, the GNC 250XL will provide correct navigation guidance to the waypoints
contained in the database, regardless of the datum selected.

UNIT SETTINGS
Map Datums

SECTION

6

To change the map datum to one listed in Appendix F:
1. Press and hold M, and use O to highlight the map datum page.
2. Press C twice.
3. Use O to highlight the current map datum.
4. Use K to change the datum.
5. Press C to complete.

Map datum page showing the default WGS 84
datum. This setting should be used unless your
paper chart specifies a different datum.

To create a user datum:
1. Press and hold M, and use O to highlight the map datum page.
2. Press C twice.
3. Use O to highlight ‘Define user datum?’. Press E.
4. Enter the five parameters of the map datum using K and O. Press E to accept a
field. The signs of each value (+/-) should follow the convention: WGS84-local geodetic
system.
5. Use O to highlight ‘ok?’, and press E.
6. To activate the user datum, select ‘USER’ on the map datum page as described above.

User datum page. To use this function you must
enter the parameters as differences from the WGS
84 default.

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UNIT SETTINGS
I/O Settings

The last page available under the GNC 250XL’s setup menu is the I/O setup page.
The I/O setup page lets you configure the GNC 250XL to input RTCM SC-104 correction
data, output to a RS-232 mapping device or a PC (with the optional GARMIN PC Kit or
other mapping software) and select the appropriate baud rate. The I/O setup page only
provides access to I/O channel 2 input/output. For information on using I/O channel 1,
please see your GNC 250XL installation manual.
To change the output settings for I/O channel 2:
1. Press and hold M, and rotate O until the I/O setup page is displayed.
2. Press C twice, and rotate K to select ‘off’ or ‘plotting’ for output to an RS-232 device.
3. Rotate O to advance the cursor to the baud rate field.

I/O page settings

4. Use K to select the desired baud rate (300,1200, 2400, 4800 or 9600).
5. Press C to finish.

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Page 87

Appendix A
NavData® and User Data Installation and Operation

NAVDATA CARD
Saving User Data

The NavData card supplied with your GNC 250XL can be installed or removed
when the GNC 250XL is on or off. Insert the card with the thumb tab at the top, and
the beveled corner at the bottom. If the NavData card is not present when the unit is
powered on, you will receive a ‘No Jeppesen database’ message on the database confirmation page, and you will only be able to use user waypoints for navigation. If the
NavData card is removed during operation, a ‘No data card present’ warning will
appear, asking you to reinsert the data card within 30 seconds. If the card is not
replaced within 30 seconds, the GNC 250XL will automatically reinitialize. You may
also reinitialize the unit manually by pressing E.

APPENDIX

A

An optional user data card can be used to make a backup of user waypoints,
routes, etc. and transfer information to another GNC 250XL.
To save user data to the user data card:

Insert the card with the thumb tab at the top, and
the beveled corner on the bottom right.

1. Install the user data card.
2. Rotate O to highlight ‘Save user data?’. Press E to confirm.

The message ‘Saving to card’ is displayed while the GNC 250XL transfers all user
data to the User Data card. It may take a few minutes to complete the transfer. When
all user data is transferred, the GNC 250XL will instruct you to turn the unit off,
remove the user card and insert the Jeppesen NavData card. After this is complete, the
GNC 250XL is ready for normal operation.

Data card warning

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To restore user data from a user data card to the GNC 250XL:

APPENDIX

A

NAVDATA CARD

1. Install the user data card.

Saving User Data

2. Rotate O to highlight ‘Restore user data?’.
3. Press E.

The GNC 250XL will ask you which type of data to replace. You may choose
checklists, scheduler messages, user waypoints, proximity waypoints, routes, waypoint
comments, or all data.
4. Rotate K to select the type of data to replace.

Data transfer page

You may either replace or update the information in the database. Replacing the
data will replace ALL user data with the data from the card. Updating the data will
not delete unrelated material, but will only change what is necessary to use the data
received from the user data card.
5. Rotate O to select either ‘Replace?’ or ‘Update?’.
6. Press E to begin transferring data to the GNC 250XL. The GNC 250XL will now transfer
all of the data requested. This may take a few minutes.
7. To continue with more data transfer types, repeat steps 4, 5 and 6. Otherwise, press E
when ‘ok?’ is highlighted.
8. Turn the GNC 250XL off and replace the user data card with a NavData card. The GNC
250XL is now ready for normal operation.

Restore data page

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Page 89

Appendix B
Installation, Removal and Maintenance of the GNC 250XL

INSTALLATION &
MAINTENANCE

APPENDIX

B

The aviation rack is designed to allow easy removal of the GNC 250XL. This enables you to
use the unit at home to create routes, interface to a PC, etc. using an optional AC adapter.
To install the GNC 250XL into the aviation rack:
1. Insert a 3/32” allen wrench in the small hole adjacent to the dual knob.
2. Rotate the wrench counterclockwise until it stops to ensure the pawl latch is in the
proper position.
3. Insert the GNC 250XL into the aviation rack and rotate the wrench clockwise to secure the unit. To ensure
proper connector seating, gently press on the left side of the unit until tightened.

3/32” ALLEN
WRENCH

To remove the GNC 250XL from the aviation rack:
1. Insert a 3/32” allen wrench in the small hole adjacent to the dual knob.
2. Rotate the wrench counterclockwise until the GNC 250XL can be removed from the rack.

The GNC 250XL is built to exacting standards and
does not require user maintenance. If the faceplate and
lens require cleaning, use a soft cloth and non-abrasive
cleaner.
The user data is maintained by an internal battery with
a projected life of 3 to 5 years. If the GNC 250XL
detects a low memory battery, you will be informed
with the message ‘Memory battery low’. Failure to
have the battery replaced may result in loss of data
each time you turn your unit off. This will greatly
increase satellite acquisition time and no user data will
be saved. This condition will be accompanied by the
message ‘Stored data lost’.
The GNC 250XL contains a crystal oscillator which
may drift after many years of operation. If the unit
detects excessive oscillator drift, you will be informed
with the message ‘Osc needs adjustment’. When this
occurs, contact an authorized GARMIN service center
for service. Failure to do so may result in severely
degraded acquisition performance.

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Page 90

SIMULATOR

The GNC 250XL’s simulator mode allows you to plan and practice flights in your
home and office using an optional remote battery pack or AC adapter. The simulator is not accessible when the GNC 250XL is running off the master avionics
switch. All waypoint and route planning done in simulator mode will be saved in the
unit’s internal memory.
To operate the GNC 250XL in simulator mode:
1. Turn the unit on by rotating the B knob clockwise. The welcome page will appear while
the unit conducts a self test. Once the self test is complete, the welcome page will be
replaced by the operating mode page.
2. Rotate O to move the cursor over the operating mode field (‘Normal’) .

Operating mode page

3. Rotate K to select ‘Simulator’ and press the E key. The cursor will advance to the
‘ok?’ prompt.
4. Press E to confirm.

Once the GNC 250XL has been placed in simulator mode, the database confirmation page will appear, showing the operating dates, cycle number and database type
available.
To acknowledge the database information:
1. Press E.
Selecting the simulator mode.

90

After the database has been acknowledged, the initial position reference page will
appear, where you may specify the starting position for your simulated trip. You can
define the initial position by entering a waypoint identifier in the reference field, or
by manually entering coordinates in the lat/lon field.

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To enter an initial position reference by waypoint identifier:
1. Rotate O to highlight the waypoint identifier field.
2. Use K and O to spell out the identifier of the desired airport, navaid or user waypoint.

APPENDIX

SIMULATOR

C

3. Press E to confirm the identifier. The waypoint confirmation page will appear, displaying the waypoint’s position.
4. Press E to confirm the ‘ok?’ prompt.

The position page will now appear, and you may now use most of the GNC
250XL navigation features for practice and planning. You’ll also receive a ‘Do not use
for nav’ message to remind you that the simulator mode should never be used for
actual navigation. During simulator operation, you will be able to enter a ground
speed from the CDI page, and define a course to a destination from the direct-to confirmation page. Altitude may only be entered by using the VNAV function available
from the NAV menu 1 page (see page 26).

Database Confirmation Page

To enter a ground speed from the CDI page:
1. Press N and rotate O to display the CDI page.
2. Press C twice to activate the cursor in the GPS window.
3. Rotate O to highlight the ground speed field.
4. Use K and O to enter the desired speed. Press E to accept, and C to finish.

To exit the simulator mode, the GNC 250XL must be turned off by rotating the
B knob counter-clockwise until the unit shuts down. All waypoints and routes created in simulator mode will be retained in the GNC 250XL’s internal memory.

Entering an initial position reference.

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APPENDIX

D

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MESSAGES &
ABBREVIATIONS

Altitude input fail

Arrival at _____
Arrvl at offst _____

Battery low

Battery rqrs service

92

Page 92

Appendix D
GNC 250XL Messages and Abbreviations
The GNC 250XL uses the Message Page to communicate important information to you. Some
messages are advisory in nature, others are warnings that may require your intervention. This appendix provides a complete list of GNC 250XL messages and their meanings.

- The altitude serializer input is not available for
the GNC 250XL. Check the I/O settings and/or
the serializer installation. If enough satellites are
available for a 3D position fix, no pilot action is
required, providing no RAIM warnings are present. If only a 2D fix is possible, the pilot
should enter an altitude within 1,000 feet of
current indicated altitude.
- Your craft has entered the arrival alarm circle for the
indicated waypoint.
- Your craft has entered the arrival alarm circle
for the indicated waypoint offset by the parallel
track distance.
- The optional remote battery pack is low on
power and limited operating time remains. The
battery should be recharged for continued
operation.
- A problem has been detected in the optional
remote battery pack. The battery should be serviced at an authorized GARMIN service center.

Cannot chng actv wpt - An attempt has been made to modify the position of
the ‘active to’ or ‘active from’ waypoint. The GNC
250XL will not allow the modifications.
Cannot nav lockd rte - An attempt has been made to activate a route
containing a locked waypoint. The GNC 250XL
cannot perform navigation in this situation.
Cannot ofst goto rte - An attempt has been made to engage the offset
navigation feature while the GNC 250XL is navigating using a single waypoint route. The GNC
250XL will not allow offset navigation in this
situation.
Checklist is full
- The selected checklist is full. No new items can
be added until existing items are deleted.
COM failed
- The comm in the GNC 250XL has failed. Take
the unit to an authorized GARMIN service center immediately.
Comment memory full -The waypoint comment memory is full. You
must delete existing waypoint comments before
adding new ones.

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Configuration reset

Data card failed

Data card write fail

Degraded accuracy

Do not use for nav
EEPROM write fail

Final altitude alert

Fuel/Air input fail

Page 93

- The GNC 250XL has detected a failure in its
installation configuration memory. Data from
the user memory has been used to reset the
configuration. Check the installation settings
for correctness. If the message persists, the
unit is not usable and should be taken to an
authorized service center for repair.
- The GNC 250XL has detected a problem
with the data card. The data is not usable
and the card should be returned to Jeppesen
or an authorized GARMIN service center.
- The user data card failed to program. The
card should be returned to an authorized
GARMIN service center.
- The GNC 250XL has detected poor satellite
geometry while RAIM is not available.
Additional cross-checking with a secondary
navigation source should be performed to
verify the integrity of the GPS position.
- The GNC 250XL is in the simulator mode
and must not be used for actual navigation.
- The GNC 250XL has detected a failure while
programming its installation configuration
memory. The unit is not usable and should
be taken to an authorized service center.
- The suggested altitude is within 1000 feet of
the final altitude entered on the VNAV
Planning page.
- The fuel and/or air data input is not available
to the GNC 250XL. Check the I/O settings or
fuel/air data system installation.

MESSAGES &
ABBREVIATIONS

Inside SUA
Invald CPA wpt _____

Invalid copy route

Invalid CPA route

Invalid SAR route
Leg not smoothed

APPENDIX

D

- You have entered a Special Use Airspace.
- The closest point of approach cannot be created
from the waypoint entered on the CPA Page.
This occurs when the computed point does not
fall on one of the route legs, or when a unique
waypoint name for the closest point of approach
cannot be found.
- A non-empty route was selected for a copy
operation. A route must be empty before
another route can be copied to it.
- The selected route contains less than two
waypoints and cannot be used for CPA operations.
- The selected route does not contain exactly
two waypoints and cannot be used for SAR
operations.
- The upcoming leg is too short for smooth
waypoint transitions. Expect a rapid change
in the CDI.

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APPENDIX

D

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Page 94

MESSAGES &
ABBREVIATIONS

Offset nav in effect
Ofst too big for rte
Osc needs adjustment

Poor GPS coverage
Prox alarm-press NAV
Memory battery low

Near SUA < 2 nm

No DGPS position
No RTCM input
Need alt - press NAV

Offset nav cancelled
94

- The battery that sustains user memory is low
and should be replaced by an authorized
GARMIN service center as soon as possible.
Failure to do so may result in loss of stored
data, including all user waypoints and routes.
- Your position is within 2 nautical miles of an
SUA, and your current course will not take
you inside.
- Not enough data is available to compute a
differential GPS (DGPS) position.
- DGPS data, in an RTCM SC-104 format, is
not available.
- The GNC 250XL needs altitude input in
order to start and/or continue 2D navigation.
Press the NAV key and enter your antenna
altitude on the Position page. The altitude
you enter should be as accurate as possible.
An inaccurate altitude will directly translate
into inaccurate position information.
- Offset navigation has been cancelled due to a
direct-to operation or modification of the
active route.

Proximity overlap

Proximity wpt locked

Proximity wpt moved

Proximty wpt deleted

Pwr down and re-init

- Offset navigation mode is in effect.
- The parallel track distance is too large for the
active route.
- The GNC 250XL has detected excessive drift in its
internal crystal oscillator which may result in
longer acquisition time. The unit should be taken
to an authorized service center immediately.
- The GNC 250XL cannot acquire sufficient
satellites necessary to provide navigation.
- Your craft has penetrated the alarm circle of a
proximity waypoint. Press NAV to see the bearing
and distance to the proximity waypoint.
- The circles defined by two proximity waypoints overlap. When entering the area of the
overlap, the GNC 250XL will warn you of
the closest proximity waypoint, but not both.
You should be certain this condition is
desirable.
- At least one proximity waypoint is locked
because the waypoint has been removed
from the Jeppesen NavData®, the data card
is missing, or the data card has failed.
- One or more proximity waypoints were
moved at least 0.33 arc minutes due to a
database change.
- One or more proximity waypoints were
deleted while receiving data from the PC
Interface Kit.
- The GNC 250XL is unusable until power has
been cycled and the unit re-initialized.
Abnormal satellite conditions may exist.

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Page 95

RAIM not available

- The GNC 250XL is unable to cross-check its
position using RAIM. You may continue to
navigate using visual flight rules. Your position
should be verified every 15 minutes using
other navigation sources. If you have selected
a CDI scale other than ‘Auto’, selecting a larger
CDI scale may remove the conditions causing
this message.
RAIM position warn
- RAIM has detected position errors. If you have
selected a CDI scale other than ‘Auto’, selecting
a larger CDI scale may remove the conditions
causing this message.
RAM failed
- The GNC 250XL has detected a failure in its
internal memory. If the message persists, the
GNC 250XL is unusable and should be taken
to an authorized GARMIN service center.
Rcvr needs service
- The GNC 250XL has detected a condition
requiring service in the receiver hardware. The
GNC 250XL should be taken to an authorized
GARMIN service center.
Ready for navigation
- The GNC 250XL is ready for navigation.
Receiver failed
- The GNC 250XL has detected a failure in the
receiver hardware. If the message persists, the
GNC 250XL is unusable and should be taken
to an authorized GARMIN service center.
Remote ENT key stuck - The remote ENT key is stuck in the ‘pressed’
state. Check the installation.
Remote XFR key stuck - The remote XFR key is stuck in the ‘pressed’
state. Check the installation.

MESSAGES &
ABBREVIATIONS

ROM failed

Route is empty
Route is full

Route wpt deleted

Route wpt locked

Route wpt moved

RTCM input fail

APPENDIX

D

- The GNC 250XL has detected a failure in its
permanent memory. If this message occurs, the
unit is unusable and should be taken to an
authorized GARMIN service center.
- An attempt has been made to activate an
empty route.
- An attempt has been made to add more than
31 waypoints to a route. The GNC 250XL will
not allow more than 31 waypoints per route.
- One or more route waypoints were deleted
while receiving data from the optional PC
Interface Kit.
- At least one route waypoint is locked because
the waypoint has been removed from the
Jeppesen NavData®, the data card is missing,
or the data card has failed.
- One or more route waypoints were moved at
least 0.33 arc minutes due to a database
change.
- The DGPS data signal was being received but
has now been lost. Check wiring.
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Page 96

SUA ahead < 10 min

APPENDIX

D

MESSAGES &
ABBREVIATIONS

Searching the sky

Start altitude chng
Steep turn ahead

Stored data lost

Stuck mic/tx disabled

96

- The GNC 250XL is in the search-the-sky
mode. Allow the unit to complete data collection before turning it off.
- The altitude change entered on the VNAV
Planning page is about to begin.
- This message appears approximately 90 seconds prior to a turn that requires a bank angle
in excess of 25 degrees in order to stay on
course. Turn anticipation will not be provided
for the turn.
- Stored user data, including waypoints, routes
and satellite orbital data have been lost due to
a low memory battery or inadvertent master
reset.
- The microphone/headsets have been transmitting continuously for 35 seconds, and the
transmitter has been disabled. Releasing the
transmit key will allow you to transmit again.
If this message persists, check the installation.

- The projected course and current speed will
take you inside an SUA within the next 10
minutes.
SUA near & ahead
- Your position is within two nautical miles of
an SUA and your current course will take
you inside.
Timer expired
- The approach timer has expired.
User data RX started
- Data receive operations have started.
Usr data TX complete - Data transmit operations are complete.
VNAV cancelled
- The VNAV function has been cancelled due to a
change in the active route.
WGS 84 datum selectd - The system map datum was changed to
WGS 84 because the selected map datum
has been removed from the NavData card,
the data card is missing, or the data card has
failed.
Wpt comment locked - At least one waypoint comment is locked
because the waypoint has been removed
from the Jeppesen NavData®, the data card
is missing, or the data card has failed.
Wpt exists _____
- You have entered a waypoint name on the
AutoStore™ Page or User Waypoint Catalog
Page that already exists in memory. Enter a
waypoint name that does not exist.
Wpt memory full
- The waypoint memory is full. You should
delete unused waypoints to make room for
new waypoints.

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Page 97

This section of Appendix D provides a complete list of GNC 250XL abbreviations and
their meanings.
ALTAPPAPRAPTARTCCARVATFATSAVGSAZMBRGCASCDICL BCL CCLRCPACTACTAFCTFCTRCTSCUMDALT-

Altitude
DEGApproach
DEPApproach
DISAirport Waypoint
DME Air Route Traffic Control Center DOPArrival
DTKAerodrome Traffic Frequency ELEVAutomatic Terminal Information ENDURService (ATIS)
EPEAviation Gas
ESAAzimuth (bearing)
ETABearing
ETECalibrated Airspeed
FIRCourse Deviation Indicator
FLOWClass B
FOBClass C
FPMClearance Delivery
FRClosest Point of Approach
FSSICAO Control Area
FTCommon Traffic Advisory
FTFrequency
GLCommon Traffic Advisory
GNDFrequency
GPSCenter (ARTCC)
GSCourse To Steer
HDGCumulative
HGDensity Altitude
IALT-

Degrees
Departure
Distance To Waypoint
Distance Measuring Equipment
Dilution of Precision
Desired Track
Elevation
Endurance
Estimated Position Error
Enroute Safe Altitude
Estimated Time of Arrival
Estimated Time Enroute
Flight Information Region
Fuel Flow Rate
Fuel On Board
Feet Per Minute
From
Flight Service Station
Feet
Full Time
Gallons
Ground
Global Positioning System
Ground Speed
Heading
Inches of Mercury
Indicated Altitude

MESSAGES &
ABBREVIATIONS

APPENDIX

D

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D

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Page 98

MESSAGES &
ABBREVIATIONS

ILSInstrument Landing System
IGImperial Gallons
INTIntersection Waypoint
JET A- Jet Fuel - Type A
JET B- Jet Fuel - Type B
KHKilometers Per Hour
KMKilometers
KTKnots
LBPounds
LCLLocal
LENLength
LFOB- Leftover Fuel On Board
LFLOW- Left Fuel Flow
LOCLocalizer
LTLiters
MAG VAR-Magnetic Variation
MBMillibars Of Pressure
MFMandatory Frequency
MHStatute Miles Per Hour
MIStatute Miles
MICMicrophone
MINMinimum
MIN - Minutes
MOA- Military Operations Area
MPM- Meters Per Minute
MPSMeters Per Second

MSAMTMULNDBNMNPNROBS-

Minimum Safe Altitude
Meters
Multicom
NDB Waypoint
Nautical Miles
Non-Precision
Nearest
Omni-directional Bearing Select
(Inbound Course Select)
OTHOther
ºCDegrees Celsius
ºFDegrees Fahrenheit
PCPilot Controlled
POSN- Position
PRES- Barometric Pressure
(Altimeter Setting)
PROX- Proximity
PRXProximity
PTPart Time
PTXPre-Taxi
PWR- Power
RDRRadar
REQRequired
RFReference
RFLOW- Right Fuel Flow
RNGRange

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RNWYRSTCDRSVRTERXSARSECSEQSGLSLCTSRFCSTRTACANTASTAT TEMPTMATRKTRNTRSATWRTXUUNIURAUSER-

Page 99

Runway
Restricted
Reserves
Route
Receive Only
Search And Rescue
Seconds
Sequence
Signal
Select
Surface
Steer To
TACtical Air Navigational Aid
True Airspeed
Total Air Temperature
Temperature
ICAO Terminal Control Area
Track Angle
Turn Angle
Terminal Radar Service Area
Tower
Transmit Only
UTC Time
Unicom
User Range Accuracy
User Waypoint

USRUTCVNVNAVVORWPTWXXFR-

User Waypoint
Universal Time Coordinated
(GMT/ Zulu)
VNAV or Vertical Navigation
Vertical Navigation
VOR Waypoint
Waypoint
Weather
Transfer

MESSAGES &
ABBREVIATIONS

APPENDIX

D

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Page 100

SPECIFICATIONS

Appendix E
Specifications
PHYSICAL
Size:
Weight:
Rack Size:
Rack Weight:

6.25”W x 5.8”D x 2”H (159mm x 147mm x 51mm)
41 ounces (1.16kg)
6.32”W x 5.64”D x 2”H (161mm x 143mm x 51mm)
11 ounces (0.31kg)

POWER
** Subject to accuracy degradation to 100m 2DRMS under
the US DOD-imposed Selective Availability Program.

Input:

10-15V DC with power cable (aircraft power)
Optional remote battery pack
115V or 230V AC w/ optional adapter

ENVIRONMENTAL
Temperature:

-4° F to 158° F (-20°C to 70°C) Operating
-67°F to 185°F (-55°C to 85°C) Storage

PERFORMANCE
Comm:
Whenever the GNC 250XL is connected to the
optional remote battery pack and power from the
master switch is lost, the unit will revert to battery
power. To continue navigation, press any key when
the power down page appears.

Receiver:
Acquisition Time:
Update Rate:
Accuracy:
Dynamics:

760 channel, aviation band 118-136.975 MHz
5 watt minimum transmit power
12 channel PhaseTrac12™
45 seconds (typical)
15 seconds (warm start, with ephemeris)
1 per second, continuously
15 meters (49ft.) RMS**
999 knots velocity, 3g acceleration

INTERFACES
100

ARINC 429, Plotting (NMEA 0183 V2.0), Aviation, PC Interface, Altitude
Serializer, Fuel Sensor, Fuel/Air Data Computer

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Page 101

Appendix F
Map Datums
ADINDAN

Ethiopia, Mali, Senegal,
Sudan
AFGOOYE
Somalia
AIN EL ABD 1970
Bahrain Island, Saudi Arabia
ANNA 1 ASTRO 1965
Cocos Islands
ARC 1950
Botswana, Lesotho,
Malawi, Swaziland, Zaire,
Zambia, Zimbabwe
ARC 1960
Kenya, Tanzania
ASCENSION IS 1958
Ascension Island
ASTRO B4 SOROL ATOLL Tern Island
ASTRO BEACON “E”
Iwo Jima Island
ASTRO DOS 71/4
St. Helena Island
ASTRONOMIC STN 1952 Marcus Island
AUSTRALIAN GEOD 1966 Australia, Tasmania Island
AUSTRALIAN GEOD 1984 Australia, Tasmania Island
AUSTRIA NS
Austria
BELGIUM 1950
Belgium
BELLEVUE (IGN)
Efate and Erromango
Islands
BERMUDA 1957
Bermuda Islands
BOGOTA OBSERVATORY Colombia
BUKIT RIMPAH
Indonesia
CAMP AREA ASTRO
Antarctica
CAMPO INCHAUSPE
Argentina
CANTON ASTRO 1966
Phoenix Islands
CAPE
South Africa
CAPE CANAVERAL
Florida, Bahama Islands
CARTHAGE
Tunisia
CH-1903
Switzerland
CHATHAM 1971
Chatham Island (New
Zealand)
CHUA ASTRO
Paraguay
CORREGO ALEGRE
Brazil
DANISH GI 1934
Denmark
DJAKARTA (BATAVIA)
Sumatra Island (Indonesia)

DOS 1968
EASTER ISLAND 1967
EUROPEAN 1950

EUROPEAN 1979
FINLAND HAYFORD 1910
G. SEGARA
GANDAJIKA BASE
GEODETIC DATUM 1949
GGRS 87
GUAM 1963
GUX 1 ASTRO
HERAT NORTH
HJORSEY 1955
HONG KONG 1963
HU-TZU-SHAN
INDIAN BNGLDSH NEPAL
INDIAN MEAN VALUE
INDIAN THAILAND VIETN
INDONESIA 74
IRELAND 1965
ISTS 073 ASTRO 1969
JOHNSTON ISLAND 1961
KANDAWALA
KERGUELEN ISLAND
KERTAU 1948
L.C. 5 ASTRO
LIBERIA 1964
LUZON MEAN VALUE
LUZON MINDANAO IS

APPENDIX

MAP DATUMS
Gizo Island
(New Georgia Islands)
Easter Island
Austria, Belgium, Denmark,
Finland, France, Germany,
Gibraltar, Greece, Italy,
Luxembourg, Netherlands,
Norway, Portugal, Spain,
Sweden, Switzerland
Austria, Finland,
Netherlands, Norway,
Spain, Sweden, Switzerland
Finland
Borneo
Republic of Maldives
New Zealand
Greece
Guam Island
Guadalcanal Island
Afghanistan
Iceland
Hong Kong
Taiwan
Bangladesh, India, Nepal
India
Thailand, Vietnam
Indonesia
Ireland
Diego Garcia
Johnston Island
Sri Lanka
Kerguelen Island
West Malaysia, Singapore
Cayman Brac Island
Liberia
Philippines
Mindanao Island

F

101

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Page 102

LUZON PHILIPPINES

APPENDIX

F

MAP DATUMS

MAHE 1971
MARCO ASTRO
MASSAWA
MERCHICH
MIDWAY ASTRO 1961
MINNA
NAD27 ALASKA
NAD27 BAHAMAS
NAD27 CANADA
NAD27 CANAL ZONE
NAD27 CARIBBEAN

NAD27 CENTRL AMERICA

NAD27 CONUS
NAD27 CUBA
NAD27 GREENLAND
NAD27 MEXICO
NAD27 SAN SALVADR IS
NAD83
NAHRWAN MASIRAH IS
NAHRWAN SAUDI ARABIA
NAHRWAN UNITD ARAB E
NAPARIMA BWI
NETHERLAND TRIAG ‘21
NOU TRIAG FRANCE
NOU TRIAG LUXEMBOURG
OBSERVATORIO 1966

102

OLD EGYPTIAN
OLD HAWAIIAN KAUAI
OLD HAWAIIAN MAUI
OLD HAWAIIAN MEAN
OLD HAWAIIAN OAHU

Philippines
(excluding Mindanao Isl.)
Mahe Island
Salvage Islands
Eritrea (Ethiopia)
Morocco
Midway Island
Nigeria
North American 1927- Alaska
Bahamas (excluding San
Salvador Island)
Canada (including
Newfoundland Island)
Canal Zone
Caribbean (Barbados,
Caicos Islands, Cuba,
Dom. Rep., Grd. Cayman,
Jamaica, Leeward and
Turks Islands)
Central America (Belize,
Costa Rica, El Salvador,
Guatemala, Honduras,
Nicaragua)
Mean Value (CONUS)
Cuba
Greenland (Hayes Peninsula)
Mexico
San Salvador Island
North American 1983Alaska, Canada, Central
America, CONUS, Mexico
Masirah Island (Oman)
Saudi Arabia
United Arab Emirates
Trinidad and Tobago
Netherlands
France
Luxembourg
Corvo and Flores Islands
(Azores)
Egypt
Kauai
Maui
Mean Value
Oahu

OMAN
ORD SRV GRT BRITAIN

Oman
England, Isle of Man,
Scotland, Shetland Islands,
Wales
PICO DE LAS NIEVES
Canary Islands
PITCAIRN ASTRO 1967
Pitcairn Island
PORTUGUESE 1973
Portugal
POTSDAM
Germany
PROV SO AMERICAN ‘56 Bolivia, Chile,Colombia,
Ecuador, Guyana, Peru,
Venezuela
PROV SO CHILEAN 1963 South Chile
PUERTO RICO
Puerto Rico & Virgin Isl.
QATAR NATIONAL
Qatar
QORNOQ
South Greenland
REUNION
Mascarene Island
ROME 1940
Sardinia Island
RT 90
Sweden
SANTO (DOS)
Espirito Santo Island
SAO BRAZ
Sao Miguel, Santa Maria
Islands (Azores)
SAPPER HILL 1943
East Falkland Island
SCHWARZECK
Namibia
SOUTH AMERICAN 1969 Argentina, Bolivia, Brazil,
Chile, Colombia, Ecuador,
Guyana, Paraguay, Peru,
Venezuela, Trinidad/Tobago
SOUTH ASIA
Singapore
SOUTHEAST BASE
Porto Santo and Madeira
Islands
SOUTHWEST BASE
Faial, Graciosa, Pico, Sao
Jorge and Terceira Islands
(Azores)
TANANARIVE OBSV 1925 Madagascar
TIMBALAI 1948
Brunei and East Malaysia
(Sarawak and Sabah)
TOKYO
Japan, Korea, Okinawa
TRISTAN ASTRO 1968
Tristan da Cunha
USER
User datum
VITI LEVU 1916
Viti LevuIsland/Fiji Islands
WAKE-ENIWETOK 1960 Marshall Islands
WGS 72
World Geodetic System 1972
WGS 84
World Geodetic System 1984
YACARE
Uruguay
ZANDERIJ
Surinam

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Page 103

Appendix G
Index
A
Abbreviations
Accessory list
Activating a route
Activating a route in reverse
Active frequency
Active to & from waypoints
Active route page
Adding waypoints to a route
Airport comments page
Airport communications page
Airport runway page
Airport position page
Airport identification page
Airport information
Altitude
Altitude buffer
Approach information
Approach timer
Arrival alarm setting
Automatic zoom
AutoStore™
Auto-tune
B
Battery saver
Backlighting

97-99
iii
67
67
3, 33
62
71
66, 72
40-41, 54
43
44
42
41
40
18
84
42
28
79
76
51
34

80
82

APPENDIX

INDEX

C
Cautions
ii
CDI
4-6, 12, 78
CDI page
4-6, 11-13, 78
CDI sensitivity setting
12, 78
Channel 2 I/O
86
Checking GPS coverage
20-21, 30
Checklists
27-28
Clear key
viii
Clock function
29
Closest point of approach (CPA)
68
Communication features
33-36
Communications pages
33-36, 43
Communication frequencies
3, 33
Communication window
3
Contrast
81
Controlled airspace
42, 58-61
Course select
64
Copying routes
68
Creating user waypoints
48-50
Cursor key
viii, 3
D
Database
Data fields
Date & time
Deleting user waypoints
Deleting routes
Deleting waypoints from routes
Density altitude

37
13-14, 16
29
53
67
67, 73
24

G

103

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INDEX

Page 104

Direct-to cancelling
9,63
Direct-to key
vii,5,63
Direct-to navigation
62-64
Display contrast
81
Display mode
81
Displaying airports
77
Displaying identifiers
77
Displaying airspace boundaries
78
DOP
20
Downloading data to another GNC 250 87
Duplicate waypoints
55
E
Editing routes
Editing user waypoints
ENT key
Entering waypoints
EPE
Emergency channel select
ETE (estimated time en route)
F
Foreword
Frequency restrictions
Fuel planning

104

66,72
49-50,53
viii
39,48-50
20
36
16

i
17,43
24-25

G
Going to a nearest airport
GPS planning
Ground speed
Ground track (TRK)

57
30
16
16

H
‘Hold’ on a waypoint

74

I
Inner knob
Installation of the GNC 250XL
Intersections
I/O Outputs

viii
89
38,47
86

K
Key functions
Knob functions

vii,viii
vii,viii

L
Locked waypoints
M
Magnetic variation
Map datums
Map display
Map orientation
Map page
Map scales
Map setup display
Measurement units
Messages
MSG key
N
NAVCOM page
NavData cards
NAV Key
NAV menu 1
NAV menu 2
NDBs
NRST key

56

79
85,101-102
6-7
15
6-8,11,14-16
8,15
76
83
2,25,31,58,92-96
viii, 75

4,8,11,16-17,35
33, 87-88
vii,4,11
11, 23-28
11, 28-32
38,46
vii,9,57

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Nearest airport
Nearest SUA
Nearest waypoints
O
OBS
Offset navigation
Orientation
Outer knob
P
Packing list
Parallel track
Position page
Power/volume knob
Power on (normal)
Power off
Proximity Waypoints
R
RAIM prediction
RAIM protection
Radar information
Receiver status
Reference waypoint
Removal of the GNC 250XL
Renaming user waypoints
Restoring user data
Reversing a route
Route catalog page
Route comments
Route key
Route navigation
Routes

Page 105

9,57,79
58
9,57

74
70
15
viii

iii
65,70
4,11,18-19
vii
1
10
37,52

30
78
42
21
19
89
53
88
67
65
65
vii
62
62-74

Runway page
Runway surface
S
Satellite acquisition
Satellite data page
Satellite information
Satellite status page
Scheduler
Search and rescue operations
Settings submenus
Simulator mode
Special Use Airspace (SUA)
Specifications
Standby frequency
Storing user data
SUA alert page
SUA altitude fields
SUA messages
SUA settings page
Sunrise/sunset planning
Squelch
T
Table of contents
Time
Transfer key
Trip planning
Trip timer
Trip timer settings
True air speed
Turn anticipation

44
44,80

APPENDIX

INDEX
2
22
21-22
2,11,20-22
31
69
75
90
58-61
100
3,17,33
87
59
60
58,61
61,84
32
vii, 35

G

v-vi
29
viii,3,33
23
29,82
82
24
74
105

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APPENDIX

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INDEX

Page 106

U
Unit settings
Units of measure
User data cards
User waypoints
V
Vertical navigation (VNAV)
Volume
VORs

26-27
vii,35
38,45

W
Warranty
Waypoint categories
Waypoint comment list
Waypoint comments page
Waypoint confirmation page
Waypoint entry
Waypoint holding
Waypoint identification page
Waypoint information
Waypoint key
Waypoint list
Waypoint menu
Waypoint scanning
Waypoint sequencing
Waypoints with comments
Winds aloft

iv
38
37,54
54
55
39
73-74
39
37-56
vii,37
53
37-38
56
73-74
54
26

Z
Zoom in/out
106

75-86
83
87
38,48-51,53

8,15

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Page 107

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Page 108

© 1997 GARMIN Corporation
1200 East 151st Street Olathe, KS 66062
GARMIN (Europe) LTD
Unit 5, The Quadrangle, Abbey Park Industrial Estate, Romsey, SO51 9AQ, UK
Web Site Address: www.garmin.com
Part No. 190-00067-60 Rev. A



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