New Stratus ESG ADS-B Out transponder

3 min read

Pilots across the US have been relying on the Stratus ADS-B receiver for nearly 3 years now to deliver subscription-free in flight weather and traffic to their iPad and ForeFlight. While this portable receiver delivers all the tangible benefits promised from the FAA’s ADS-B system, it does not meet the 2020 ADS-B Out requirement that pilots need to comply with when flying in airspace that currently requires a transponder.

To satisfy this requirement, pilots will need to equip their aircraft with an ADS-B Out system, which takes the form of a new or updated panel-mount transponder (portable devices do not comply with the FAA’s stringent requirements). In addition the transponder must include or be connected to a WAAS GPS source to provide accurate aircraft position data.

While there are several low-cost ADS-B Out transponders on the market, the added complexity of integrating with a WAAS GPS has proven expensive for aircraft owners from both an equipment and installation cost standpoint. And even after the ADS-B Out system is installed, aircraft owners then face additional costs to add the ADS-B In solution to their panel for displaying weather and traffic.

The Stratus ESG 1090ES transponder includes a WAAS GPS and integrates directly with the Stratus 2 ADS-B receiver.

The Stratus ESG 1090ES transponder includes a WAAS GPS and integrates directly with the Stratus 2 ADS-B receiver.

Appareo, the developer behind Stratus, recognized the situation that many pilots face with this deadline and developed a new low-cost 1090ES ADS-B Out transponder, the Stratus ESG, that takes a new approach to this problem. This all-in-one solution replaces your existing transponder with a modern digital device that is approved for all altitudes, including the flight levels. The transponder includes an integrated WAAS GPS, eliminating the need to purchase or upgrade an existing GPS.

Appareo also recognized that the cost and complexity to install many of the existing ADS-B Out transponders is exceedingly high, so they focused on developing a system that would be simple for avionics shop to install. Stratus ESG connects directly to the existing belly-mounted transponder antenna and also includes a WAAS GPS antenna. For typical single-engine piston aircraft, Stratus ESG will require approximately half the installation time as compared to a remote-mounted 978 Mhz UAT ADS-B Out system.

What really makes the Stratus ESG unique though is its direct integration with the portable Stratus 2 receiver. Once installed pilots can connect their portable Stratus 2 with a few wires to the Stratus ESG, allowing the portable Stratus 2 to take advantage of the exterior remote-mounted GPS and ADS-B antennas to deliver position data, weather and traffic to an iPad running ForeFlight. In addition to improved reception, this allows you to mount Stratus 2 out of sight under the panel or in a glove box. This connection will also deliver power to the device, eliminating the need to charge it in between flights.

Pilots flying with the Stratus 2 portable ADS-B receiver will also see a significantly improved traffic picture in ForeFlight after equipping with Stratus ESG. As we’ve discussed in the past, the only way to receive the complete traffic picture in ForeFlight (or with any ADS-B In traffic display) is to participate in the ADS-B system by transmitting ADS-B Out, and flying with Stratus ESG allows you to satisfy that requirement.

Stratus ESG is currently in the FAA certification process and will complete final submission for certifications late this year. It will sell for $3,490, which includes the digital transponder, GPS antenna and install kit.

For more information on the ADS-B system, check out our latest webinar video on the topic: Understanding ADS-B, a Pilot’s Guide



72 replies
  1. D gill
    D gill says:

    Looks great ! Questions for APPAREO. 1) how does the new ADS-B OUT transponder receive PRESSURE ALTITUDE ? ( needed for the ADS-B OUT data transmission stream) . 2) can the new APPAREO ADS-B OUT transponder provide ADS-B IN received TRAFFIC DATA (via the STRATUS II ADS-B IN box) to other displays in the cockpit ? Getting “ALL” of the traffic data on Foreflight iPad displays is great but providing it to other existing displays in the cockpit would be best.

    • John Zimmerman
      John Zimmerman says:

      We’ll try to answer all your questions:

      1. Stratus ESG is connected to the aircraft’s altitude encoder which in turn is connected to the static port on the outside of the aircraft. One of the two cables going between the Stratus ESG Transponder and the Stratus 2 portable provides both data and power. It’s over this data cable that the transponder sends the pressure reading to Stratus 2.

      2. Short answer is no. Stratus ESG was designed specifically for legacy, non-glass aircraft where, in effect, the pilot uses his iPad and ForeFlight Mobile as his glass panel. One of the reasons it’s price is close to 1/2 of other systems that provide a panel mounted transponder with an internal GPS is that it’s not burdened with the extra cost and certification work needed to support glass panels. There are lots of great options for pilots with glass panels but the vast majority of the piston GA fleet is flying with steam gauges and that’s the segment that Stratus ESG is targeting.

  2. Doug
    Doug says:

    Love my Stratus 2 and ForeFlight. If it is compatable with my 430 W it is a winner especially if it’s easy and inexpensive to install. So same question as Gill D, we all want to have redundancy in the the cockpit. See you at Fun and Sun!

  3. Manny
    Manny says:

    The article states that WAAS is a transponder requirement to provide position data. This is incorrect. The FAA does not require WAAS to meet the mandate. Regular GPS is sufficient for position sensing.

  4. Jack Tyler
    Jack Tyler says:

    I’m disappointed with the price. So far Appareo has only described this product as providing ADS-B Out performance, coupled with transponder functionality all of us already have. I don’t find I need better ADS-B In station reception for my Stratus II nor do I have the need for another Stratus II charging capability, the two Stratus-related ‘benefits’. I thought I might be a likely customer for the ESG but now I’m not so sure, having seen some of the other, less expensive ‘Out’ boxes.

    • John Zimmerman
      John Zimmerman says:

      Jack, it’s important to focus on the total install price on any ADS-B Out package. Stratus is a 1090ES transponder, which is a little more expensive up front than a 978/UAT model, but it makes up for it during install in most cases. With a 978 box, you have to keep your existing Mode C transponder, and the ADS-B Out box is remote mounted. That often takes much longer to install than a 1090ES box that goes right in the radio stack. In a number of airplanes, it’s twice as long (and twice as expensive) to install – the interior may have to come out completely, for example.

      Also, many 978 solutions require the purchase of a separate control head so you can sync your ADS-B Out squawk code and your Mode C squawk code. This can easily add $1500 and a fair amount of hassle. That’s all assuming your current transponder is in good shape and passes the tests. With a 1090ES box, all of these issues are eliminated because you’re getting an all-in-one solution.

      Stratus ESG includes everything (even the GPS antenna). There is no extra control head to buy and it’s 50% less to install. You can even sell or trade in your existing Mode C transponder. It’s not the right answer for everyone, but make sure to read all the footnotes and do the installation math on whatever ADS-B Out you go with.

  5. AirCoach
    AirCoach says:

    Will it be a mode S transponder ? – and I to like D gill, was wondering about the altitude input to the transponder, built in or ??
    – and finally, who will be approved to do maintenance on this box in the future.

    • John Zimmerman
      John Zimmerman says:

      Yes, this is a 1090ES transponder, so it’s like a Mode S. Appareo is developing a complete dealer network to service these avionics.

  6. Luke
    Luke says:

    Looks like a great solution to me. So for install on this could you is it fair to assume cost to be inline with what install has cost in past for standard mode c transponder?

  7. Andy T.
    Andy T. says:

    Waiting for a solution with WiFi built in so info will be displayed on my iPad. The Stratus EGS is close to meeting my needs, I don’t need a new transponder, and I don’t have a Stratus portable (I have a SkyRadar). I will wait to see what develops in the next 4.5 years.

    • John Zimmerman
      John Zimmerman says:

      Andy, Stratus ESG will interface with portable ADS-B receivers besides Stratus 2. Stay tuned.

  8. P Ayres
    P Ayres says:

    Can you discuss how this unit will work for those of us that already have the common Garmin 430W? We don’t need an extra WAAS GPS receiver or a GPS antenna. In other words, does already having the Garmin 430W provide any advantage with the Appreo device?

    • John Zimmerman
      John Zimmerman says:

      The 430W doesn’t really add any advantage – Stratus ESG has its own GPS. The benefit is that it’s a simpler install – connecting that 430W to a transponder can be an issue sometimes.

      Since you already have a WAAS GPS antenna, you may be able to use a splitter, meaning you wouldn’t have to install another GPS antenna. That would save on installation, but not all shops like splitters.

  9. Andy T.
    Andy T. says:

    Oh yes add a AHRS to the unit along with WiFi you will have a winner for our legacy aircraft without Garmin 430W

    • John Zimmerman
      John Zimmerman says:

      The AHRS is built into the Stratus 2 portable, so you have that option. Because it’s in the portable instead of a certified unit, the price is much lower.

    • John Zimmerman
      John Zimmerman says:

      It meets the 2020 mandate for an ADS-B Out position source, but it cannot be connected to an existing GPS or MFD or anything.

  10. Tony Vallillo
    Tony Vallillo says:

    Will this interface with other ADSB in units than the Stratus, and will it work with other apps than Foreflight? I use and need Garmin Pilot as a primary navigator, for example, and I do not use Foreflight. And the Stratus apparently does not work with any other apps than Foreflight.

  11. john f
    john f says:

    If the past 5 years is any indication as to what the next 5 years holds (affordable technology in the cockpit), then I’m expecting to see a lot more capability for essentially the same cost (including installation) as the Stratus ESG.

    We’re still 4+ years out from the mandate. Buckle your seat belts folks; there’s still plenty more to come before you will be forced to part with your hard earned cash $.


  12. Charles Largay
    Charles Largay says:

    Looks like a goo d fit for me. I use steam gauges, Foreflight, and Stratus portable in. And I can go up to class A. Now this would provide me a WAAS gps and out in one box.
    Now, what about dimensions? VERY important for me, especially depth.

    • Bret Koebbe
      Bret Koebbe says:

      The front faceplate measures the same as the Bendix/King KT-76A, so it will easily replace most legacy transponders in the same space. The depth is approximately 9.69 in. behind the panel including connectors.

  13. HRM
    HRM says:

    Frankly, I consider this a great boon to the aging GA fleet. The probability of me putting in a fully glass panel is near nil. I have an aging NARCO AT-50B that will not last forever.Pulling it out and replacing it with not only Mode S and ADS-B out, but a data source for ADS-B in on my iPad is a godsend.

    I heard an ugly rumor that the Mooney M20 series is not on the STC list. Please tell me that is not rue.

    • John Zimmerman
      John Zimmerman says:

      Good news – one of the senior guys at Appareo owns a Mooney M20, so I’m pretty sure that airplane will be on the STC list, and early at that.

      • HRM
        HRM says:

        I knew Jeff Johnson was a fellow Mooniac and hoped that he might influence the STC process. But I also know the Feds Against Aviation and how they are determined to make the simplest thing into a multi-year ordeal!

  14. Old Bob Siegfried
    Old Bob Siegfried says:

    Looks great to me! With modern technology and good old competition, things will undoubtedly get cheaper and better. Very selfishly, I am interested in the size of the box. My Stearman has room for only very short panel units. For instance my GPS is the Garmin 300XL s that is the only unit short enough to fit. Sure would be nice if the manufacturers would build those boxes shorter!

    Happy Skies,

    Old Bob

  15. Andy T.
    Andy T. says:

    Thanks, Mr. Zimmerman, I fly a 1977 Mooney 201 with steam gauges and a Mode C transponder. I fly with a SkyRadar ADS-B receiver and 2 iPads. I will never spend $10K to $25K to buy a 430W or a glass panel (I’d rather buy fuel instead). So your solution intrigues me more that I’ve have learned I can interface with my SkyRadar. Let me know how it will interface?

    • John Zimmerman
      John Zimmerman says:

      There are plans to have a variety of interface cables that work with different ADS-B receivers. Price and availability TBD at this point.

  16. Dean Fawley
    Dean Fawley says:

    Is it plug and play for the AT150 TSO Mode C transponder I currently have in my Cherokee 180?

    • John Zimmerman
      John Zimmerman says:

      Probably not, because you will need a WAAS GPS antenna to connect to Stratus ESG. The transponder itself may be a “slide-in” replacement, or at least somewhat close to it, but there will be wiring work.

  17. James Naphas
    James Naphas says:

    Hi John
    Looks great for my airplane as I already have a stratus 2.
    2 questions-
    1. Will it fit in the slot that has my Narco AT150?

    2. Will my Cessna 170A be on the STC?

    I thought your ADS-b webinar was great!

    • John Zimmerman
      John Zimmerman says:

      The 170 won’t be on the initial list, but the 172 will be so a field approval should be a good option. Don’t know the specs on the AT150, but Stratus ESG is close to a Bendix/King KT-76C. 9.69″ deep, including connectors.

  18. J.D.
    J.D. says:

    Does the ESG contain its own altitude encoder, or do I have to continue to use the one currently connected to my old Narco transponder?

    • John Zimmerman
      John Zimmerman says:

      You will need to tie into your existing encoder. But Stratus ESG is very flexible on this in terms of connection type.

  19. Ron Simonton
    Ron Simonton says:

    While I am dropping my Foreflight subscription in favor of “friendlier” apps (not captive to a single ADS-B receiver) such as WingX, FlyQ, and iFly, I find this transponder to be a step forward. While Trig and King and Garmin offer compliant ES transponders, none have integrated the compliant position source as the Appareo has done. And, the all-in-one boxes, such as Freeflight, Garmin and Navworx, still need to hook to a transponder. Trig does combine the encoder in a couple of their units, which the Appareo does not have. It is interesting, since I am in the market for at least a compliant system.

  20. Jim Lloyd
    Jim Lloyd says:

    I have a Beechcraft Sundowner with a 430W and a Garmin 327x transponder. I also use Stratus 2 and an ipad. Will the 327 transponder now be useless if I install the ESG?

  21. John Bruns
    John Bruns says:

    This is looking like a great solution for my 172. I currently have a Garmin’s GTX320A transponder. Will the ESG fit the same panel space?

  22. Bill Thompson
    Bill Thompson says:

    The price is indeed disappointing. A WAAS gps chip is a mere $30.00, so how is this price justified when existing ADS-B units without a GPS are a thousand dollars less?

    I concur with the others – there is plenty of time between now and 2020 so there is no rush. More units will be forthcoming and the price pressure is finally hitting manufacturers as we are not going to spend $5k plus for a solution and the install price.

    • John Zimmerman
      John Zimmerman says:

      Bill, a GPS that meets the mandate (not just a basic WAAS chip; has to meet TSO-C145/C146) is over $1000 usually. There are critical standards for availability and reliability, not just the accuracy of it. Appareo has really broken a price barrier here with the this combination of features.

    • John Zimmerman
      John Zimmerman says:

      As Bret said above, the front faceplate measures the same as the Bendix/King KT-76A, so it will easily replace most legacy transponders in the same space. The depth is approximately 9.69 in. behind the panel including connectors.

  23. Ken Graham
    Ken Graham says:

    I have heard alot about simplicity of installation. Have heard nothing in the last three months about FAA Next Gen buying 10,000 L3 Lynk NGT 1000 units at a cost of $1,699.00 and we can go through Dexa Capital in Washington DC to finance these high cost installations. The FAA Next Gen will guarantee loans up to $10,000.00 to have all these units professionaly installed. Most IMPORTANT. They have advertised that if owners will have them installed before April 1, 2016. The government will reimburse the owners the cost of the NGT 1000 ( $1,699.00), but not the cost of installation. So where does the General Aviation Pilot/Owner stand on that issue? Thank you for your time. Looking forward to hearing a good answer for all of us aircraft owners who want to comply. But are willing to ground their aircrafts rather than spend $5-10,000.00 on a box they might use once or twice a year. Pilot waiting for an answer.

  24. Jim watters
    Jim watters says:

    I am an A&P and an IA. Can I inststal the unit into my Cessna 195? In the past I have installed all of my avionics. It seems that now if I want to upgrade my radios, I must have an ‘approved’ shop complete the job. Some of the instal techs are off the of the street type. Not always the best work!
    P.S. I really like the Stratus 2

    • John Zimmerman
      John Zimmerman says:

      You could install it Jim, but I’m not sure about the warranty implications if you’re not an Appareo dealer. Might want to contact them for details.

  25. Nor Becker
    Nor Becker says:

    Original Stratus 1 user, now with a 2 and love it and ForeFlight. Don’t forget all the Commander 112/114 owners with your STC. Most Rockwell Commanders have KT 76/A transponders like mine, so it would be nice if it would just slide in. I’ve had my plane for 36 years, so if you need any info. or help plz. call. 314-409-9540

    • John Zimmerman
      John Zimmerman says:

      While that’s not on the initial STC list, we will pass it on because that list will grow quickly. A field approval is also an option.

  26. HRM
    HRM says:

    FlyQ-EFB just added support for the Stratus.

    The ESG is a MODE S TRANSPONDER (that fits where your old Mode C is) and USES THE SAME ANTENNA.

    The price is very reasonable.

  27. Blair Barwick
    Blair Barwick says:


    Very interested in this as an option for my Cessna 140, a legacy aircraft !
    What will I need to add to have “in” capability, showing up on “Foreflight” displayed on an I-Pad ?

    Do you have a date yet for certification ?



  28. Nor Becker
    Nor Becker says:

    We have a large and active Commander Owners Group, and most are older models that would be interested.

  29. Bill Harpole
    Bill Harpole says:

    Finally a solution that make since for older small aircraft. I fly a 172B and have been looking at updating my transponder anyway. Now I can both update the transponder and be in compliance for close to the same cost as a transponder.

  30. Larry Jensen
    Larry Jensen says:

    I’m one of many Stratus I owners. How will the ESG work for us?!
    There’s only been talk about the Stratus II. Please explain in detail
    rather than anecdotal… hookups, costs, etc.
    Thanks for your great products!

    • John Zimmerman
      John Zimmerman says:

      Larry, you’ll be able to connect to the external ADS-B antenna through Stratus ESG, but there is no external GPS option on Stratus 1. However, you will benefit fully from the complete traffic picture that ESG will create for you.

  31. Larry Jensen
    Larry Jensen says:

    Thanks, John for your helpful input on Stratus 1. Will there be printed installation hookups, connections, info in the ‘box”? How is the Stratus 1 ‘wired’ to the ESG? Can the ESG use the Stratus 1 GPS data? And what about WAAS requirement? How does that work with Stratus 1?

    • John Zimmerman
      John Zimmerman says:

      Stratus ESG needs to be installed by an avionics shop, and they will have access to the full installation manual. Stratus 1 will use the power and ADS-B cables to connect to a remote port under the panel – makes it easier than plugging directly into the back of ESG. Stratus 1 cannot accept remote GPS input, so that’s not an option (it is on Stratus 2). Stratus ESG fulfills the WAAS requirement because it’s built in, it just can’t send that GPS info to Stratus 1.

  32. Gail A. Hammans
    Gail A. Hammans says:

    If the Stratus II has a built-in WAAS GPS, why is there also one on the ESG? Is this a possible conflict or problem and why is the antenna required on the ESG and not the StratusII?

    • John Zimmerman
      John Zimmerman says:

      The Stratus 2 has a built-in WAAS GPS, but it is not a certified GPS source, so it doesn’t meet the standard for ADS-B Out. That’s why Stratus ESG also has a GPS built-in, because it does meet the mandate.

  33. Jason Skelton
    Jason Skelton says:

    John, as I’m reading through all the comments I’m developing a great appreciation for your patience. Although there are some things that are yet to be worked out (mostly if the market will accept it as offered) I am wholly appreciative that you have a collaboration that is willing to make an offer at all.

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