Garmin 328 Manual

Mode S Transponder
pilot’s guide
GTX™ 328

© Copyright 2007
Garmin Ltd. or its subsidiaries
All Rights Reserved
Except as expressly provided herein, no part of this manual may be reproduced, copied,
transmitted, disseminated, downloaded or stored in any storage medium, for any purpose
without the express prior written consent of Garmin. Garmin hereby grants permission to
download a single copy of this manual and of any revision to this manual onto a hard drive or
other electronic storage medium to be viewed and to print one copy of this manual or of any
revision hereto, provided that such electronic or printed copy of this manual or revision must
contain the complete text of this copyright notice and provided further that any unauthorized
commercial distribution of this manual or any revision hereto is strictly prohibited.
This manual is written for software version 5.00 or later, and is not suitable for earlier software
versions. Some differences in operation may be observed when comparing the information in
this manual to later software versions.
Software License Agreement
BY USING THE GTX 328, YOU AGREE TO BE BOUND BY THE TERMS AND CONDITIONS
OF THE FOLLOWING SOFTWARE LICENSE AGREEMENT. PLEASE READ THIS
AGREEMENT CAREFULLY.
Garmin grants you a limited license to use the software embedded in this device (the
“Software”) in binary executable form in the normal operation of the product. Title, ownership
rights and intellectual property rights in and to the Software remain in Garmin.
You acknowledge that the Software is the property of Garmin and is protected under the
United States of America copyright laws and international copyright treaties. You further
acknowledge that the structure, organization and code of the Software are valuable trade
secrets of Garmin and that the Software in source code form remains a valuable trade secret of
Garmin. You agree not to decompile, disassemble, modify, reverse assemble, reverse engineer
or reduce to human readable form the Software or any part thereof or create any derivative
works based on the Software. You agree not to export or re-export the Software to any country
in violation of the export control laws of the United States of America.
CAUTION: The GTX 328 should be turned off before starting or shutting
down aircraft engine(s).
NOTE: Contact a Garmin dealer for software updates.
January 2007 Part Number 190-00420-03 Rev. A Printed in USA

Limited Warranty
This Garmin product is warranted to be free from defects in materials or workmanship for
two years from the date of purchase. Within this period, Garmin will at its sole option, repair
or replace any components that fail in normal use. Such repairs or replacement will be made
at no charge to the customer for parts or labor, provided that the customer shall be responsible
for any transportation cost. This warranty does not cover failures due to abuse, misuse,
accident or unauthorized alteration or repairs.
THE WARRANTIES AND REMEDIES CONTAINED HEREIN ARE EXCLUSIVE AND IN
LIEU OF ALL OTHER WARRANTIES EXPRESS OR IMPLIED OR STATUTORY, INCLUDING
ANY LIABILITY ARISING UNDER ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE, STATUTORY OR OTHERWISE. THIS WARRANTY GIVES
YOU SPECIFIC LEGAL RIGHTS, WHICH MAY VARY FROM STATE TO STATE.
IN NO EVENT SHALL GARMIN BE LIABLE FOR ANY INCIDENTAL, SPECIAL, INDIRECT
OR CONSEQUENTIAL DAMAGES, WHETHER RESULTING FROM THE USE, MISUSE, OR
INABILITY TO USE THIS PRODUCT OR FROM DEFECTS IN THE PRODUCT. Some states
do not allow the exclusion of incidental or consequential damages, so the above limitations
may not apply to you.
Garmin retains the exclusive right to repair or replace the unit or software or offer a full
refund of the purchase price at its sole discretion. SUCH REMEDY SHALL BE YOUR SOLE
AND EXCLUSIVE REMEDY FOR ANY BREACH OF WARRANTY.
To obtain warranty service, contact your local Garmin Authorized Service Center. For
assistance in locating a Service Center near you, visit the Garmin website (www.garmin.com)
or call Garmin Customer Service at one of the numbers shown below.
Garmin International, Inc. Garmin (Europe) Ltd.
1200 East 151st Street Unit 5, The Quadrangle, Abbey Park
Olathe, Kansas 66062, U.S.A. Industrial Estate, Romsey, SO51 9DL, U.K.
Phone: [phone] Phone: [phone]
FAX: [phone] FAX: [phone]
NOTE: The expected coverage from the GTX 328 is limited to “line of
sight”. Low altitude or aircraft antenna shielding by the aircraft itself may
result in reduced range. Range can be improved by climbing to a higher
altitude. It may be possible to minimize antenna shielding by locating
the antenna where dead spots are only noticed during abnormal flight
attitudes.

The GTX 328 transponder is powered on by pressing the STBY, ALT or ON keys, or by a remote avionics master
switch (if applicable). After power on, a start-up page is displayed while the unit performs a self test.
Mode Selection Keys
OFF  Powers off the GTX 328. Pressing STBY, ON or ALT
Key powers on the transponder displaying the last active
identification code.
STBY  Selects the standby mode. When in standby mode,
the transponder will not reply to any interrogations.
ON  Selects Mode A. In this mode, the transponder replies to interrogations,
as indicated by the Reply Symbol ( ). Replies do not include altitude information.
ALT  Selects Mode A and Mode C. In ALT mode, the transponder replies to
identification and altitude interrogations as indicated by the Reply Symbol ( ). Replies
to altitude interrogations include the standard pressure altitude received from an external
altitude source, which is not adjusted for barometric pressure. The ALT mode may be
selected in aircraft not equipped with an optional altitude encoder; however, the reply
signal will not include altitude information.
Any time the function ON or ALT is selected the transponder becomes an active part of
the Air Traffic Control Radar Beacon System (ATCRBS). The transponder also responds to
interrogations from TCAS equipped aircraft.
Code Selection
Code selection is done with eight keys (0 – 7) providing 4,096 active identification codes.
Pushing one of these keys begins the code selection sequence. Digits that are not yet entered
appear as dashes. The new code is activated when the fourth digit is entered. Pressing the CLR
Key moves the cursor back to the previous digit. Pressing the CLR Key when the cursor is on
the first digit of the code, or pressing the CRSR Key during code entry, removes the cursor and
cancels data entry, restoring the previous code. Press the CLR Key up to five seconds after code
entry is complete to return the cursor to the fourth digit. The numbers 8 and 9 are not used for
code entry, only for entering a Count Down time, and contrast and display brightness.

Important Codes:
1200 The VFR code for any altitude in the US (Refer to ICAO standards elsewhere)
7000 The VFR code commonly used in Europe (Refer to ICAO standards)
7500 Hijack code (Aircraft is subject to unlawful interference)
7600 Loss of communications
7700 Emergency
7777 Military interceptor operations (Never squawk this code)
0000 Military use
Avoid selecting codes 0000, 7500, and all codes in the 7600-7777 range. These codes
trigger special indicators in automated facilities. An aircraft’s transponder code is used for ATC
tracking purposes, therefore exercise care when making routine code changes!
Keys for Other GTX 328 Functions
IDENT Pressing the IDENT Key activates the Special Position Identifica-
tion (SPI) Pulse for 18 seconds, identifying your transponder return from
others on the air traffic controller’s screen. The word ‘IDENT’ will appear in
the upper left corner of the display while the IDENT mode is active.
VFR Sets the transponder code to the pre-programmed VFR code selected
in Configuration Mode (this is set to 7000 at the factory). Pressing the
VFR Key again restores the previous identification code. If the VFR Key is
disabled (dependent upon installation configuration) a ‘VFR Key Disabled’
message appears, to indicate that no operation took place.
FUNC Changes the page shown on the right side of the display. Display
data includes Pressure Altitude, Flight Time, Altitude Monitor, Count Up
and Count Down timers. Also displays Outside Air Temperature, Density
Altitude, Contrast, and Display (dependent upon installation configuration).
START/STOP Starts and stops the Altitude Monitor, Count Up, Count
Down and Flight timers.
CRSR Initiates starting time entry for the Count Down timer and cancels
transponder code entry.
CLR Resets the Count Up, Count Down and Flight timers. Cancels the
previous keypress during code selection and Count Down entry. Returns
cursor to the fourth code digit within five seconds after entry.
8 Reduces Contrast and Display Brightness when the respective fields
are displayed (dependent upon installation configuration) and enters the
number eight into the Count Down timer.
9 Increases Contrast and Display Brightness when the respective fields
are displayed (dependent upon installation configuration) and enters the
number nine into the Count Down timer.

PRESSURE ALT: Displays the altitude data supplied to the GTX 328 in feet,
hundreds of feet (i.e., flight level), or meters, (dependent upon installation
configuration.
FLIGHT TIME: Timer start is configured as either Manual or Automatic.
W hen Manual, d isplays the Flight Time, controlled by the START/STOP
and CLR keys . When Automatic , the timer begins when take off is sensed.
ALTITUDE MONITOR: Controlled by START/STOP Key. Activates a
voice alarm and warning annunciator when altitude limit is exceeded.
OAT/DALT: Displayed when the GTX 328 is configured with temperature
input. Displays Outside Air Temperature and Density Altitude.
COUNT UP TIMER: Controlled by START/STOP and CLR keys.
COUNT DOWN TIMER: Controlled by START/STOP, CLR, and CRSR
keys. The initial Count Down time is entered with the 0 – 9 keys.
CONTRAST: This page is only displayed if manual contrast mode is
selected during installation configuration. Contrast is controlled by the 8
and 9 keys.
DISPLAY:
This page is only displayed if manual backlighting mode is selected
during installation configuration. Backlighting is controlled by the 8 and 9
keys.
Altitude Trend Indicator
When the ‘PRESSURE ALT’ page is displayed, an arrow may be displayed to the right of
the altitude, indicating that the altitude is increasing or decreasing. One of two sizes of arrows
may be displayed depending on the vertical speed rate. The sensitivity of these arrows is set by
an authorized Garmin Aviation Service Center.
The GTX 328’s options are normally set at time of installation. To request any changes of
the GTX 328 parameters, contact an authorized Garmin Aviation Service Center.
Function Display

Timer Operation
To operate the Flight Timer:
1. Press the FUNC Key until ‘FLIGHT TIME’ is displayed.
2. If the GTX 328 is configured with Automated Airborne Determination, the timer begins
automatically when the unit senses that the aircraft has become airborne. The timer
may be reset to zero at every take off, continue accumulating time at take off or may be
controlled manually.
3. If desired, press START/STOP to pause or restart the timer.
4. Press CLR to reset the timer to zero.
5. If the timer is configured to start automatically it will stop when the Automated Airborne
Determination senses that the aircraft is on the ground.
To operate the Count Up timer:
1. Press the FUNC Key until ‘COUNT UP’ is displayed.
2. If necessary, press CLR to reset the Count Up timer to zero.
3. Press START/STOP to begin count up.
4. Press START/STOP again to pause the timer.
5. Press CLR to reset the timer to zero.
To operate the Count Down timer:
1. Press the FUNC Key until ‘COUNT DOWN’ is displayed.
2. Press CRSR and use the 0 - 9 keys to set the initial time. All digits must be entered (use
the 0 Key to enter leading zeros).
3. Press START/STOP to begin count down.
4. Press START/STOP again to pause the timer.
5. When the Count Down timer expires, the ‘COUNT DOWN’ banner is replaced with a
flashing ‘EXPIRED’, and the time begins counting up.
6. Press CLR to reset the timer to the initial time value.
Automatic ALT/GND Mode Switching
If the GTX 328 is configured for Automated Airborne Determination, normal operation
begins when take off is sensed. When the aircraft is on the ground the screen automatically
displays GND. The transponder does not respond to ATCRBS interrogations when GND
is annunciated. When a delay time is set in the Configuration Mode, the GTX 328 waits a
specified length of time after landing before changing to GND mode.
Failure Annunciation
If the unit detects an internal failure, the screen displays FAIL. When FAIL is annunciated
no transponder data is transmitted.

Mode S Data Transmission
In addition to 4096 code and pressure altitude, the GTX 328 is capable of transmitting
aircraft identification, transponder capability and maximum speed range. “Aircraft
Identification” is commonly referred to as FLT ID (Flight Identification). The GTX 328 may
be configured by the installer to allow the flight crew to enter FLT ID for each flight. An
example is when air-carrier service requires changing the FLT ID.
The FLT ID may consist of the aircraft registration or a flight number as agreed upon with
the local aviation authority. In either case, the FLT ID must be the same aircraft identification
that appears in the flight plan to correlate the aircraft identification seen on ATC radar with the
correct voice call sign for the aircraft. If no flight plan is filed with the aviation authority (as
may be permitted by regulations), the FLT ID entered is the aircraft registration marking.
When flight crew entry of the FLT ID is not required, the installer configures the
system to report the aircraft identification according to local aviation requirements. In this
configuration, alteration of the FLT ID by the flight crew is not possible.
Entering a Flight ID Number
When configured for FLT ID PWR-UP ENTRY at installation, the flight crew must enter
the Flight ID before the GTX 328 will operate. After the flight crew enters the correct Flight
ID, the aircraft identification that is transmitted in response to ATC radar interrogations is
properly correlated with the associated call sign for voice communication with the aircraft.
If the FLT ID PWR-UP ENTRY is required but does not appear at power up, contact a
Garmin authorized service center for GTX 328 configuration.
No space is needed when entering Flight ID characters. When a Flight ID contains a
space, the GTX 328 automatically removes the spaces upon completion of Flight ID entry.
At system power-up the FLT ID may
appear with no number (as shown) or with the
last FLT ID entered. The cursor covers the
entire FLT ID field.
If the Flight ID appearing at turn-on is
correct, press the CRSR Key to move the cursor
to the “OK?” field. Press CRSR again to accept
the FLT ID. The transponder then begins
normal operation.
When no FLT ID appears or the FLT
ID must be changed, press the number keys
corresponding to the alphanumeric character
entry. For example, to enter the letter “R” press
the 5 Key four times.

Each time an alphanumeric character is entered, press the CRSR Key to move the cursor
to the next blank field. Pressing the CLR Key moves the cursor back to the previous character .
After the complete FLT ID is entered, press the CRSR Key to move the cursor to the “OK?”
field. Press CRSR again to accept the FLT ID.
When FLT ID entry is complete the transponder begins normal operation.
If an error is made while entering a FLT ID, press the
CLR Key to back up to any point,
including highlighting the “OK?” field. If an incorrect FLT ID is discovered after the unit
begins operation, turn the GTX 328 off. Then turn it back on again and reenter the correct
FLT ID.
Audio Alerts
(Setting options; male/female voice or tone, and volume level.)
• “Leaving Altitude” Altitude deviation is exceeded.
• “Timer Expired” for countdown time.

© 2007 Garmin Ltd. or its subsidiaries
Garmin International, Inc.
1200 East 151st Street, Olathe, Kansas 66062, U.S.A.
Garmin (Europe) Ltd.
Unit 5, The Quadrangle, Abbey Park Industrial Estate, Romsey, SO51 9AQ, U.K.
Garmin Corporation
No. 68, Jangshu 2nd Road, Shijr, Taipei County, Taiwan
www.garmin.com
Part Number 190-00420-03 Rev. A