Part #:

Model: GTX-330D




Mode S Datalink Transponder

Part Number :

GTX 330D



  • Solid-state Mode S Level 2 datalink digital transponder with Diversity
  • Solid-state transmitter provides 250 watts nominal power output
  • Low power consumption, low heat emission, no warm up time
  • Easy-reading DSTN Liquid Crystal Display reverses yellow numbers out of black for optimal viewing
  • Dedicated VFR button allows for quick and easy 1200/VFR squawking
  • Offers timing functions such as flight time and count-up/down times
  • Other features include automatic ALT/GND switching and remote ident
  • Outside air temperature (OAT) display (temp input required)
  • Density altitude computations (temp input required)
  • Altitude monitor with voice audio alert
  • Datalink provides FAA Traffic Information Services (TIS) which receive traffic advisories and warnings from ATC to be displayed on MFD or GPS 400, GNC 420, GNS 430, GPS 500, and GNS 530
  • Available with black or gray face



TSO Compliance: C112, C112d, ETSO-C112d Temperature Range: -20C to +55C
Weight: 4.2 lbs installed w/rack & connectors Power Requirements: 11.0 to 33.0 VDC; Typical power input: 27 watts
Altitude: 55,000 feet Transmitter Frequency: 1090 MHz
Transmitter Power: 250 watts nominal Receiver Frequency: 1030 MHz
Receiver Sensitivity: -74 dm nominal for 90% replies Mode A Capability: 4096 ident codes
Mode C Capability: 25 foot increments from -1000 to 62,700 feet Dimensions: 6.25"W x 1.65"H x 11.25"D
Part Number: description:
011-00455-10 With Antenna Diversity, Black bezel, Mode S Datalink Transponder
011-00455-30 With Antenna Diversity, Gray bezel, Mode S Datalink Transponder


- Mode S Datalink Transponder
Price Condition Status
- Mode S Transponder w/ES (Gray)
Price Condition Status
- Mode S Datalink Transponder

NSN: 5841-01-571-2660

Price Condition Status

Click on a question below to see the answer. If you have a question about this model that is not answered below, please contact

Extended Squitter (or 1090 ES) is the Mode S transport protocol for ADS-B operation. 1090 MHz extended squitter is an ADS-B link for air carrier, commercial, and private aircraft. With 1090ES, the Mode S transponder supports an extended squitter (ES) message. Currently, this message provides position, velocity, and heading information.

The ES versions of the Garmin GTX33, GTX-330, and GTX-330D transponders comply with FAA TSO C-166A which dictates the minimum performance standards (MPS) for 1090 MHz ADS-B equipment. Existing Garmin GTX Mode S transponders without ES can be upgraded through Garmin to include the Extended Squitter feature. On average the Extended Squitter option costs an additional $1000-$1500 USD.

It is very important to note that in order for the ES data to be broadcasted, the transponder must be interfaced to a compatible GPS that meets TSO C145a/C146a. These TSOs explains the performance standards for WAAS GPS receivers. As of 2009, the CNX80, GNS480, GNS400W/500W series and G1000 are the only Garmin GPS receivers that meet this criteria.
Utilizing more than one antenna to improve the quality and reliability of radio signal is called antenna diversity.

Heavy and/or faster aircraft utilize top and bottom antenna configurations to eliminate the possibility of signal blind spots caused by shadowing. Lighter, slower general aviation aircraft typically only have 1 antenna and do not require antenna diversity. Although not completely uniform, the transmission pattern of a typical antenna provides adequate radiation above and below in relation to most GA aircraft even when the antenna is on the bottom of the aircraft.
The Mode S aircraft identification code is listed on AC Form 8050-3, Certificate of Aircraft Registration, as the International Civil Aviation Organization (ICAO) Aircraft Address Code. If the aircraft registration does not contain this information, aircraft owners with a Mode S transponder can obtain an aircraft identification code from the FAA Aircraft Registry in Oklahoma City, Oklahoma. This may be accomplished by writing to the following FAA address:

Federal Aviation Administration
Aircraft Registration Branch AFS-750
P.O. Box 25504
Oklahoma City, OK 73125-0504

You may also call:
Newly Overhauled parts obtained from Garmin are designated with an N in their part number. This usually follows the 010- in the part number. As with most Garmin 010 part numbers, the N part numbers are for ordering purposes only and do not actually appear on the dataplate of the unit.
In relation to the transponder technology, a squawk refers to a response that a transmitter responder (i.e. transponder) is making to an interrogation from Air Traffic Control (ATC). In a classic Mode A/C transponder, a squawk response included very basic aircraft ID, general status, and pressure altitude information.

A squitter or squit is a transmission that frequently sends aircraft ID and position data while not being interrogated. In some Mode S transponders and ADS-B devices, the squit transmission can include up to almost 50 parameters including lat/long position, direction of flight, velocity, and more.



Bendix/King, L3 and ACSS released the NXT-700/MST-70B as form fit replacement for the MST-67A. It is DO-260B compliant to meet the ADS-B Out mandate.

There are other options besides the MST-70B to gain ADS-B compliance. There are various STCs that allow the removal of the Bendix/King transponder system and installation of Rockwell Collins or Garmin transponders. Upgrade prices vary depending on actual installed equipment. 

Regarding ADS-B for the Garmin GTX-330 transponders, the best solution is to simply have the units converted by Garmin to include the ES (Extended Squitter) upgrade. This upgrade is about $2000 approximately. Additionally, a WAAS/GPS source will need to be interfaced. We can process the upgrade for you or any other Garmin dealer can as well.

In relation to NE (New) parts, many OEMs change their prices and availability without any notice to dealers or the industry. Therefore, through the REQUEST or RFQ indication, we ask that customers contact us for the most accurate price and availability.

In relation to SV & OH parts, the used parts aftermarket in the aviation industry is not an infinite supply. It is a dynamic, constantly changing market that is significantly affected by and susceptible to highs and lows in supply and demand. Therefore, although we attempt to, at times, we are unable to predict the exact moment when an item may be available. Once again, through the REQUEST or RFQ indication on our website, we ask that customers contact us for the most current and accurate price and availability.