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ADS-B Options

ADS-B Options

Single-band, dual-band, USB or serial, out options, tablet redundancy? You have lots of ADS-B choices…

The open nature of the GRT Avionics EFIS allows our customers many ADS-B choices and more competitive pricing than can be expected from “closed” systems. Often customers call us to ask which solution we recommend for their situation, so we have put our answers in writing.

ADS-B Out Requirements

ADS-B out (transmitter) is not required today, but will be required to operate in certain airspace in the United States after January 1, 2020. Two types of ADS-B output are available, ES (extended squitter using 1090 MHz), or UAT (universal access transceiver using 978 MHz).

Will you need ADS-B out?

Not necessarily. The requirements are similar to the need for mode C transponders today. Depending on where you live, and where you fly, it can be practical to fly without mode C transponder today, and ADS-B out in the future.

Starting Jan 1, 2020, exactly where in the US will ADS-B out be required, and which of the two types of ADS-B out will I need?

If you are going to fly above 18,000’ (Class A Airspace), your airplane will require a 1090 MHz extended squitter ADS-B output.

If you are going to fly in any of the following airspace, you will be required to have either the 1090 MHz extended squitter ADS-B output, or the 978 MHz Universal Access Transceiver (UAT) ADS-B output.

  • Class B or C airspace, or above it
  • Above 10,000 feet unless within 2,500 feet of terrain.
  • In class E airspace over the Gulf of Mexico, within 12 nautical miles of the US coastline, and at or above 3000 feet.
  • Within 30 nautical miles of any the airports listed in the appendix A.

I decided I need ADS-B out. Which type should I buy? ES, or UAT?

UAT Advantages: Can be less expensive, as it can be used with an existing Mode C transponder.

UAT Drawbacks: Limited to flight below 18,000 feet in the US. Fewer foreign countries may adopt this standard in the future.

ES Advantages: Allows flight at any altitude in the US. Most likely to be accepted around the world. Allows airplane-to-airplane traffic awareness.

ES Drawbacks: Can not be used with an existing transponder, except the GTX330.

I might fly outside the US someday. What foreign countries require ADS-B out now, or are expected to?

The most relevant foreign countries are listed here. As of September 2016:

  • Canada – Not required. No plans to mandate it. Extended squitter is supported in the Hudson Bay area, and provides additional ATC services.
  • Mexico – No mandate at this time, but a proposal would make it required using either UAT, or ES, as in the US mandate, beginning January 1, 2020.
  • Australia – ES required only above 29,000 feet, in some other airspace, and for IFR flights starting February 2017.
  • Europe – Required for all aircraft by June 7, 2020.

Does GRT Avionics recommend ES or UAT ADS-B output for US based aircraft?

We are comfortable recommending either UAT or ES ADS-B output for the vast majority of our customers, as this will allow flight in Mexico, Canada, and other nearby countries, such as the Bahamas, Dominican Republic, etc. Also, it is our opinion, that often the standards established by the US eventually become adopted by other countries, implying that even the UAT output may become a standard in other countries, especially those that may have US general aviation airplane traffic. Mexico’s proposal to adopt the US standard, including UAT out, is a good example. It seems unlikely US general aviation aircraft, which comply with all US mandates, would be forbidden to enter any nearby country due to future ADS-B regulatory requirements.

When should I equip my airplane with ADS-B Out?

It is your choice. If you are building a new airplane, we are close enough to 2020 to plan on including it in your new airplane, although plenty of time exists to add the ADS-B output in the future. The addition of the ADS-B out does not affect the instrument panel, and if you pre-wire for an ADS-B out device, it would not be hard to add it later. We would suggest waiting to purchase your ADS-B out until your airplane is nearing completion. Prices are slowly dropping, and more options are becoming available to GRT Avionics customers.

If you have a flying airplane, and you have a newer transponder that you expect to keep using, adding a uAvionix echoUAT is a good option that you can do at your lesiure. It is a one-box solution, easy to install, and you will immediately have weather and traffic.

I have a flying airplane, but don’t want to commit to add ADS-B out at this time. Any suggestions?

Yes. Why not add an ADS-B receiver? You will immediately have weather and some traffic, and if you are willing to put together a Stratux ADS-B receiver, this option can cost as little as $100. We built ours and found it to be a fun project, and the data it provides makes you wonder how you flew without it. The hardest part (and its not that hard) is loading the software onto the SD memory card. Get help, or buy one pre-programmed if you wish. If you don’t want to build one, you can buy them assembled, or opt for a Redenna SkyRadar or other commercially available ADS-B receiver. If you don’t need it for your airplane someday (because your future ADS-B out includes ADS-B in, for example) you can bring it home and watch the airliners fly over by connecting it to your phone or PC. Fun!

ADS-B In (Receivers)

ADS-B in is not required, but provides significant benefits, and typically at little or no cost. Different sets of data can be received on two bands, the ES band, and the UAT band.

Any GRT Avionics EFIS can display ADS-B traffic and weather provided by an ADS-B receiver includes a RS-232 serial, or USB output in the standard GDL-90 format. GRT Avionics prides itself on keeping our avionics usable as far into the future as practical, and this is why even our first display unit, produced more than 13 years ago when ADS-B did not exist, includes ADS-B capability via a free software update.

UAT Band

The UAT band provides the pilot with weather and traffic data from a ground station. The weather data include METARs, Nexrad weather, TFRs, and more. If your airplane includes valid ADS-B output, you will also see all airplanes with operating transponders or ADS-B output. The only drawback of the UAT band data is that it typically can not be received on the ground, or at low altitudes, and thus can not be used for flight planning, or for traffic awareness until reaching a sufficient altitude to receive data from the ground station. Be aware that if you do not have valid ADS-B out, you will see traffic triggered by other airplanes, but there is no assurance airplanes near you will be shown. Also remember that aircraft without transponders (or ADS-B output) will not show up.

ES Band

The ES band allows you to receive data directly from airplanes that are equipped with an ES ADS-B output. This is strictly airplane-to-airplane, and does not rely on a ground station. This means that you could see this traffic with ES ADS-B output, even when you are on the ground.

Which band does GRT Avionics recommend for an ADS-B receiver?

Most of the data you will use will be coming from the UAT receiver. UAT coverage as of September 2016 is already very good, even as low as 1500’ above the ground. This website illustrates the current coverage: http://www.faa.gov/nextgen/programs/adsb/ICM/

If you often operate at airports with commercial traffic, or at airports that do not have good UAT coverage, the ES 1090 band receiver may allow you to see airliner and other traffic while on the ground and near the airport. Low-flying airplanes, such as agricultural airplanes, may also be displayed using this receiver.

Of course if you choose a dual band receiver, you will have the best of both worlds.

What are the most popular choices with my GRT Avionics EFIS for ADS-B Out?

uAvionix EchoUAT

  • Requires an existing mode C or S transponder. 
  • Provides ADS-B UAT out.
  • Dual-band  1090MHZ / UAT receiver
  • Requires GRT Avionics ADS-B compliant GPS ($495)
  • Total Cost: About $1490

Trig TT22

  • Provides Mode S transponder output, and ES ADS-B output
  • Requires GRT Avionics ADS-B compliant GPS ($495)
  • Does not provide ADS-B in.
  • Any GRT EFIS can function as the transponder control head
  • Total Cost : About $2700


  • Provides Mode C transponder output, UAT ADS-B output
  • Provides ADS-B in on UAT Only
  • Requires GRT Avionics ADS-B compliant GPS ($495)
  • Total Cost: About $3000

Garmin GTX330-ES

  • Provides mode S Transponder output, ES ADS-B output

Garmin GTX345

  • Closed System – Format of the data output is proprietary to Garmin. Not usable at this time.


ADS-B Receivers Supported by GRT

Manufacturer Model Type Mount EFIS
uAvionix echoUAT 978/1090 MHz P Serial WiFI No $995
(Raspberry Pi – based)
Various 978/1090 MHz P Serial WiFi No  Varies from
$100 and up
Radenna SkyRadar-DX 978/1090 MHz T/P USB or Serial  WiFi  No $849 
  SkyRadar-D2 978/1090 MHz T/P Serial WiFi  No $649 
Navworx ADS600-BG 978 MHz P Serial WiFi  Yes $3,800 
Free Flight Systems  XPLORER* 978 MHz P Serial  WiFi No  $685 
RANGR-FDL-978-XVR 978 MHz P  Serial WiFi Yes  $3,995 
Dual Electronics XGPS170 978 MHz T  Serial Bluetooth  No  $699 
Levil technologies iLevil SW/AW 978 MHz T/P USB or Serial   WiFi  No $1,195/
Flight Data Systems Pathfinder 978 MHz P Serial  WiFi No $549 


Mount: T=Temporary/portable, P=Permanent installation

*Requires FreeFlight’s own certified WAAS GPS to be paired with an ADS-B Out transmitter for traffic.

Engine Data Broadcast to iPad: iLevil-AW can connect to a Grand Rapids Technologies EIS engine monitor via serial link and broadcast graphical engine data to an iPad along with backup AHRS data.
Traffic reception: On all above devices except ADS600-B/G and RANGR require separate ADS-B transmitter.
WiFi and Bluetooth-enabled: Receivers transmit ADS-B information to Android or Apple tablets with appropriate applications. See manufacturers’ websites for more information. GRT EFIS Bluetooth will not work for ADS-B, only the GRT Remote App.
USB Data notes: Sport SX requires USB 2.0 hub for Radenna Skyradar D2 and DX. HXr, HX and SX systems require powered USB hub for Dual XGPS170. Plugging the Dual directly into the EFIS USB port may overload the USB power circuit because the Dual’s battery charges thru USB.
HS and WS Users: Horizon/Sport HS and WS systems do not support ADS-B through USB. They require ADS-B receivers with RS-232 serial output.
FIS-B: Weather products currently displayed on GRT EFIS systems include METARs, TAFs, AIRMETs, and regional radar. We are working to include more of the available FIS-B products, notably TFRs.

ADS-B is NOT a substitute for a pre-flight weather briefing! Know before you go!

The radar “age” displayed on the EFIS display reflects the time the radar imagery packet left the ADS-B station. There is a 7-10 minute processing delay from the time the radar sweeps the precipitation to the time it reaches the ADS-B broadcast tower. ADS-B is often referred to as “real-time” weather by many vendors, but it is not. This delay is SIGNIFICANT. Strong cells, by their nature, develop quickly and can become dangerous before they even appear on a new ADS-B data packet. Be aware of this time delay and use ADS-B and XM for strategic long-range planning only!


Recommended ADS-B OUT Transmitting Devices

Manufacturer Model Type Mount 2020
Includes 2020
Compliant GPS
uAvionix echoUAT UAT Transceiver Remote Yes No


Trig TT21  1090-ES Transponder  Panel or Remote Yes No

$2,200 (Remote)

$2,499 (Panel)

Trig  TT31   1090-ES Transponder Panel Yes No $2,675
Garmin GTX330ES   1090-ES Transponder  Panel Yes No $3,649
FreeFlight Systems  RANGR FDL-978-XVR  UAT Transceiver  Remote Yes Yes $3,995


  •  Prices are for comparison only and typical from a reputable dealer. They may not be current.
  • The only Trig product sold through GRT is the TT22 Remote transponder package with single-display serial adapter. Dual-display serial adapter is available for an additional cost and enables control from two display units.
  • GPS Source: All of the listed transponders require WAAS GPS input for ADS-B Out operation. 2020 compliance requires a GPS position source certified to ADS-B TSO standard for traffic separation. See ADS-B OUT below for more details. Compliant GPS sources are available now from TRIG and FreeFlight Systems for around $3,000.

ADS-B: How does it work?

  • It’s important to remember one concept: There are ADS-B receivers and there are ADS-B transmitters. Some boxes do both (ie. uAvionix echoUAT  UAT Transceiver), but when thinking about ADS-B processes, always keep them separated.
  • Weather Information: Free weather information (FIS-B) is broadcast from ADS-B ground towers on 978 MHz (UAT). This is received by UAT ADS-B receivers inside ADS-B coverage.
  • Traffic Information: ADS-B traffic position data (TIS-B) is broadcast from ADS-B ground towers on 978 MHz and 1090 MHz. The towers relay ADS-B Out data from “participating aircraft” and radar positions from transponder-equipped aircraft when under ATC radar coverage. Traffic information may not always be received by ADS-B receivers – even while inside ADS-B coverage. See “Tower to Airplane” below. Traffic may also be transmitted from airplane-to-airplane. See “Airplane to Airplane” below.
  • ADS-B OUT: “Participating aircraft” broadcast their position using either 978 MHz UAT transmitters or 1090-ES “extended squitter” Mode S transponders. Both types of transmitter must be paired with a with a GPS position source that meets the standards of TSO-C129, 196, or 145/146 (WAAS) for accurate determination of location. Note that a GPS receiver may be WAAS-capable without certification. The GRT VFR GPS module fits this category and currently works for ADS-B Out with Trig transponders (but NOT with Garmin GTX 330ES). The ADS-B Out mandate will require a TSO’d and ADS-B compliant WAAS GPS when it takes effect in 2020. Note that IFR-Certified WAAS GPS units are not necessarily compliant and may require software and hardware upgrades.
  • Tower-to-Airplane: ADS-B ground towers only transmit traffic position information when they are “pinged” by nearby aircraft with ADS-B Out transmitters. Therefore, if you have an ADS-B receiver but are not participating in ADS-B Out, you will not receive traffic data from the ground tower unless there is a participating aircraft broadcasting its position near you and within range of the tower. For this reason, NEVER expect or rely on traffic data unless you are also a “participant” broadcasting ADS-B Out data.
  • Airplane-to-Airplane: Some aircraft are already operating 1090-ES transponders and transmitting ADS-B Out position data on 1090 MHz. Most commercial aircraft will eventually have 1090-ES because it can be an upgrade to their existing Mode S transponders. 1090-ES will be required for ADS-B Out in Class A airspace and many areas outside the United States in 2020. If you have a single-band 978 MHz UAT receiver, you will not see these 1090-ES aircraft outside of ADS-B ground coverage. Dual-band ADS-B receivers such as SkyRadar D2 receive position information from aircraft broadcasting ADS-B Out on either 1090 MHz or 978 MHz, even if they are outside of ADS-B ground coverage.
  • Mode C transponders: The Sandia STX 165R Mode C transponder is one of the remotely-mounted transponder options for Hxr. It is capable of sharing your squawk code with a certified FreeFlight RANGR FDL978-TX stand-alone ADS-B transmitter via the FreeFlight FTM-190c adapter module, thereby completing ADS-B Out requirements without a Mode S transponder. For more information on this ADS-B option, please contact FreeFlight Systems.
Types of Data Received by ADS-B Receivers: 978 MHz UAT
Receiver Only
Dual Band
Receiver Only
978 MHz UAT Rx +
ADS-B Out Tx
Dual Band Rx +
ADS-B Out Tx
Inside ADS-B Coverage
Weather Yes Yes Yes Yes
Mode C/Mode S Traffic Incomplete Incomplete Yes Yes
1090-ES Transmitting Traffic Incomplete Air->Air Yes Yes
978 MHz transmitting Traffic Air->Air Air->Air Yes Yes
Outside ADS-B Coverage
Weather No No No No
Mode C/Mode S Traffic No No No No
1090-ES Transmitting Traffic No Air->Air No Air->Air
978 MHz transmitting Traffic Air->Air Air->Air Air->Air Air->Air


  • Incomplete means some traffic may appear on the display, but it is an incomplete picture and should not be relied upon.
  • Mode C/S traffic targets are only seen in areas with overlapping ATC radar and ADS-B coverage.
  • This chart pertains to ADS-B only. Mode S transponders can still receive traffic in TIS coverage areas.

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