Garmin GNC 250XL User Manual
GNC 250XL
Pilot’s Guide and Reference
Software Version 2.01 or above
© 1997 GARMIN Corporation
1200 East 151st Street, Olathe, Kansas 66062-3426, USA
INTRODUCTION
Foreword
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.
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
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.
i
INTRODUCTION
Cautions
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.
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
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.
CAUTION
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.
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.
INTRODUCTION
Accessories and
Packing List
Standard Package:
• GNC 250XL Unit & NavData® Card
• GPS Antenna
• Installation Rack & Connectors
• Pilot’s Guide & Quick Reference Guide
• Database Subscription Packet
• Warranty Registration Card
Optional Accessories:
• Remote Battery Pack
• AC Adapter
• PC Software/Interface Kit
• User Data Card
• 28 to 14 volt DC converter
To obtain accessories for your GNC 250XL,
please contact your nearest GARMIN dealer.
iii
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
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.
iv
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
PART TWO: REFERENCE
Section 1: Navigation with the GNC 250XL ( Nkey) . . . . . . . . . . . . . . .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 ( Wkey) . . . . . . . . . . . .37
Finding and using database and waypoint information
Section 4: Nearest Waypoints ( Tkey) . . . . . . . . . . . . . . . . . . . . . . . . .57
Finding nearest waypoints, SUAs and FSS/ARTCC frequencies
Section 5: Direct-to ( Dkey) & Route Navigation ( Rkey) . . . . . . . .62
Creating and using routes
INTRODUCTION
Table of Contents
To quickly and easily locate information
on specific tasks, please refer to the Index
on page 103.
v
INTRODUCTION
Table of Contents
Section 6: Messages and Unit Settings ( Mkey) . . . . . . . . . . . . . . . . . .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
vi
B
Key and Knob Functions
The power/volume knob controls unit power and radio volume.
INTRODUCTION
Key and Knob
Functions
Q
D
T
R
W
N
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.
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.
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.
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.
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.
vii
INTRODUCTION
Key and Knob
Functions
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.
viii
This manual will describe entering data using the
and Oknobs. 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.
K
\
E
C
O
K
The clear key is used to erase information or cancel an entry.
The enter key is used to approve an operation or complete data entry.
It is also used to confirm information, such as during power on.
The 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.
The outer knob is used to advance through pages, advance the cursor
or move through data fields.
The inner knob is used to change data or scroll through information that
cannot fit on the screen all at once.
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.
The Takeoff Tour assumes that the GPSCOMTMand 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
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
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 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.
TAKEOFF TOUR
Power On
To acknowledge the database information:
E key
1. Press the
.
The database confirmation page shows the
effective date of the Jeppesen database on the
NavData Card.
1
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 Nkey and use the Kand
O
knobs to enter the altitude shown on your altimeter. Press Ewhen 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 Mkey, 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 Magain.
:
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
Standby
Comm Window
TAKEOFF TOUR
Selecting Comm Frequencies
{
{
The Ckey 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.
To change the standby communication frequency:
1. Press Conce to activate the cursor in the comm window.
2. Rotate the outer knob (
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 Ckey twice.
O
) to select the MHz, and the inner knob (K) to select the kHz of
}
GPS Window
}
@
.
Status page with cursor active in comm window.
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
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)
Reference Waypoint Field
The position page displays your present latitude and longitude, altitude and a reference way-
point field. The altitude and reference waypoint fields are also selectable (see Section 1 for more
The map page combines a moving map display
and navigation data for complete situational
awareness.
The navigation communications (NAVCOM) page
provides a complete list of airport frequencies at
your departure and arrival airports.
4
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 Nkey:
• CDI page • Map page
• NAVCOM page • Position page
• Satellite status page • NAV menu 1
• NAV menu 2
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 Nkey
and rotating the outer knob, or by pressing the Nkey repeatedly.
{
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.
To select a direct-to destination:
D
1. Press the
key. The CDI page will appear with the destination field highlighted.
TAKEOFF TOUR
Direct-To
Navigation
2. Rotate the
tination 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
4. Repeat steps 2 and 3 to spell out the rest of the waypoint identifier.
5. Press
6. Press
K
knob to enter the first letter of the destination waypoint identifier. The des-
O
knob to the right to move the cursor to the next character position.
E
to confirm the identifier. The direct-to confirmation page will appear.
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
TAKEOFF TOUR
CDI & Map Pages
CDI page with ‘trk’ and ‘eta’ displayed.
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
The next page available from the Nkey 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
{
Data Fields
CDI page with ‘brg’ and ‘trk’ displayed.
6
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.
Airspace
Boundaries
Airport Waypoint
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
GS
TRK
TAKEOFF TOUR
Map Page
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.
DTK
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
TAKEOFF TOUR
Map Scales
NAVCOM Page
To change the map scale rotate the K knob clock-
wise to increase the scale or counterclockwise to
decrease the scale.
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:
K
1. Rotate the
2. Rotate the
knob clockwise to increase the map scale and show a larger area.
K
knob counterclockwise to decrease the map scale and show a smaller area.
Another page available under the GNC 250XL’s Nkey 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 Oone 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
2. Use the
C
key twice to activate the cursor in the GPS window.
O
knob to select the desired frequency. Press Eto place the frequency in
the standby field. The cursor will automatically advance to the next frequency on the list.
Once a direct-to is activated, the CDI page will provide navigation to the destina-
tion 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
2. Press
3. Press
C
key twice to activate the cursor in the destination field.
\
.
E
.
The GNC 250XL’s Tkey 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.
TAKEOFF TOUR
Cancelling a Direct-To
Nearest Waypoints
The nearest airport page shows up to nine
nearest airports from your present position.
To view the nine nearest airports
1. Press the Tkey. 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
To place a nearest airport frequency in the standby field
1. PressE. Press the @key to place the frequency in the active field.
To view the nearest list for other waypoint categories (VOR, NDB, etc.)
1. Rotate the Oknob to the right, or press the Tkey repeatedly.
2. Rotate Kto scroll through the list.
:
K
knob to the right.
:
:
To place a nearest airport frequency in the standby field, press E.
9
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 Ctwice to activate the waypoint field.
2. Press Eto display the waypoint identification page.
3. Rotate Oto view any additional waypoint information available.
4. Press Tto return to the nearest waypoint page.
:
To view additional nearest airports, rotate the
K knob.
To select a nearest waypoint as a direct-to destination
1. Press the Dkey. The direct-to confirmation page for the selected waypoint will appear.
2. Press Eto 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 Bknob to the left until the unit shuts off.
To review a nearest waypoint, highlight the identifier and press E.
10
:
Section 1
Navigation 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 Nkey and rotating the outer knob, or by pressing the Nkey repeatedly.
CDI page
Map page
NAVCOM page
NAV KEY
Overview
SECTION
1
NAV Menu 2
NAV Menu 1
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 Nkey pages are in use, the indicator light (U) next to the
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.
Satellite status page
Position page
N
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
Satellite Status page appears. The current receiver status is
displayed at the top left of the page.
N
key and rotating the outer knob until the
11
SECTION
1
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
Distance
Field
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).
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.
Active Waypoint
Time or Direction Field
WPT 1
S
T
R
L
NORTH
NORTH
WPT 2
BRG
TRK
G
S
DIS
A
IR
P
L
A
N
E
D
T
K
The following functions may be displayed in the ground speed field:
• 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.
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.
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.
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).
NAV KEY
Configuring the
CDI Page
SECTION
1
13
SECTION
NAV KEY
CDI &
1
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.
To change the map scale rotate the K knob clockwise to increase the scale or counterclockwise to
decrease the scale.
Map Pages
To change any of the selectable fields on the CDI page:
1. Press Ctwice to activate the cursor in the GPS window.
2. Rotate Oto highlight the field you would like to change.
3. Rotate Kto change the field to display the desired information.
4. Rotate Oto highlight another field, or Cto finish.
Map Display
Comm
Frequencies
{
Data Fields
The next page available from the GNC 250XL’s Nkey 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.
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.
14
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.
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.
NAV KEY
Map Page
SECTION
1
To select a map scale:
K
1. Rotate the
2. Rotate the
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.
knob clockwise to increase the map scale and show a larger area.
K
knob counterclockwise to decrease the map scale and show a smaller area.
The map page, showing only airports and airspaces on the map display.
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 \.
15
Navigation data is also provided on the map page to guide you during your flight.
SECTION
NAV KEY
Map &
1
The NAVCOM page lists the frequencies for your
departure (or nearest) and arrival airports in the
following order:
Departure Arrival
• Unicom • ATIS
• ATIS • Approach
• Clearance Delivery • Arrival
• Clearance Pretaxi • TCA
• Ground • TMA
• Tower • CTA
• Multicom • ARSA
• Other • TRSA
• Departure • Tower
• TCA • Multicom
• TMA • Other
• CTA • Ground
• ARSA • Unicom
• TRSA
16
NAVCOM Pages
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 - upper left corner
Ground speed (gs) - upper right corner
Ground track (trk) - lower left corner
Map scale - lower right corner (cannot be removed)
The next page available from the GNC 250XL’s Nkey is the navigation com-
munications (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.
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 Ctwice to activate the cursor in the GPS window.
2. Rotate Oto highlight the ‘brg?’ next to the frequency you wish to view.
E
3. Press
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.
Some frequencies in the NAVCOM page have tags which designate their usage:
‘tx’ – transmit only ‘rx’ – receive only
‘pt’ – part time frequency
To make any of the frequencies on the NAVCOM page the standby frequency:
1. Press Ctwice to activate the cursor in the GPS window.
2. Rotate
to begin viewing restrictions.
O
until the desired frequency is highlighted.
NAV KEY
SECTION
NAVCOM Page
NAVCOM page with receive only (rx) frequencies
and frequencies with restrictions (brg).
1
E
3. Press
matically advance to the next frequency on the list.
to make the highlighted frequency the standby frequency. The cursor will auto-
Frequency restrictions on 124.60, showing range
of applicable radials from 130º through 309º.
17
SECTION
1
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)
Reference Waypoint Field
{
Position page displaying MSA.
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
18
more complete information.
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 Ctwice to obtain a cursor in the GPS window.
2. Rotate Ountil the ‘alt/ESA/MSA’ field is highlighted.
3. Rotate Kto display the desired data. Press Cto return to normal navigation.
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
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 Ctwice to activate the cursor in the GPS window.
2. Rotate Oto highlight the category field after the fr.
3. Use Kto choose which waypoint type you would like displayed. (Choose ‘wpt’ if you
would like range and bearing from a specific waypoint to be displayed.)
4. Press Cto remove the cursor, or:
If you have selected ‘wpt’:
5. Rotate Oto advance the cursor to highlight the identifier field.
NAV KEY
Reference
Waypoint Field
Position page displaying the nearest airport
(KIXD) as the reference waypoint.
SECTION
1
6. Use the
7. Press Cto 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.
K
and Oknobs to enter the identifier name. (This waypoint identifier can be
an airport, VOR, NDB, intersection, or user waypoint.) Press
E.
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.
19
SECTION
1
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 Nand rotate Ountil the satellite status page appears.
EPE/DOP
Receiver Status
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.
The top line of the status page displays the receiver status and the current posi-
tion 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
Signal strength of
satellite being tracked (1-9)
• 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.
Satellite in view
but not receiving signal
EPE/DOP
value
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