uAvionix tailBeaconX

An all-in-one taillight and Mode S transponder.


uAvionix tailBeacon XuAvionix made a name for itself with the innovative skyBeacon and tailBeacon ADS-B Out solutions‭. ‬These 978‭ ‬MHz UAT devices‭, ‬intended to replace a wingtip strobe and taillight‭, ‬respectively‭, ‬proved popular for owners wanting a cost-effective way to get ADS-B compliance without having to‭ ‬invest in a new transponder or install other equipment inside the aircraft‭. ‬They have been especially popular among certified aircraft because of their ease of installation‭, ‬though they have penetrated the Experimental market as well‭. ‬A good product easily‭ ‬crosses over‭. ‬

With the tailBeaconX‭, ‬we can now see that these products were just a run-up in the company’s product-development plans‭. ‬Where the previous UAT devices would be fine for domestic U.S‭. ‬compliance below 18,000‭ ‬feet‭, ‬they wouldn’t work in Canada or into the flight levels‭; ‬for that‭, ‬you need a 1090‭ ‬MHz Mode S transponder‭. ‬

Believe it or not‭, ‬that’s exactly what the tailBeaconX is‮—‬a Mode S transponder‭, ‬WAAS GPS for position information and an LED taillight all in one crazy‭-‬compact‭ ‬unit‭. ‬Moreover‭, ‬uAvionix is working on Aireon compatibility‮—‬the GPS-based‭ ‬ADS-B equivalent Canada is considering‭. (‬If you’ve been paying attention‭, ‬you know that Transport Canada has been pressing for ADS-B compliance through Aireon‭, ‬which itself requires so-called antenna diversity‭, ‬or one antenna on the‭ ‬top‭, ‬one on the bottom‭. ‬That program‭ ‬was originally supposed to launch in‭ ‬2021‭ ‬but is currently on hold‭.)‬ Aireon testing has been completed but uAvionix has not yet received approval.

Weighing just 3.5‭ ‬ounces‭, ‬the tailBeaconX is a mere 4.4‭ ‬inches tall‭ (‬at the‭ ‬“wings”‭ ‬of the two antennas‭) ‬and 4.4‭ ‬inches deep as measured from the trailing edge of the antennas to the connector‭. ‬The depth inside‭ ‬the taillight well is only 2.3‭ ‬inches‭. ‬The antenna configuration is inherently‭ ‬“diverse‭,‬”‭ ‬with top and bottom elements that will be needed for Aireon compatibility‭. ‬Power consumption‭? ‬A flashlight-like half an amp‭.‬

The AV-20 display/control unit is quite compact and easy to install. Pitot and static lines plus power and data through the DB-9 connector.

Matter of Control

It’s fair to wonder that if the entire transponder is in the taillight‭, ‬how do you‭ ‬control it‭? ‬There are a few ways‭. ‬For‭ ‬one thing‭, ‬the tailBeaconX can be controlled through a common RS-232‭ ‬data‭ ‬connection‭. ‬And that means it must be connected by four wires‮—‬power‭, ‬ground and both input and output‭ ‬data‭. ‬Fortunately‭, ‬uAvionix has made the tailBeaconX compatible with existing data formats‭, ‬so it’ll respond the‭ ‬same way other remote transponders‭ ‬do‭, ‬making it an easy add-on for panels‭ ‬already equipped with ‬Grand Rapids‭, ‬MGL or other EFISes capable‭ ‬of managing a Trig STX-165‭ ‬or Apollo/Garmin SL 70‭. ‬If you have one of these EFISes and have been keeping that old Narco transponder on life support‭, ‬this may be the ideal replacement for you‭.‬

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For a lot of owners‭, ‬the tailBeaconX‭ ‬will predict installation of an AV-20‭ ‬or‭ ‬AV-30‭ ‬display head‭. ‬Formerly known by the Aerovonics brand‭, ‬the AV-20‭ ‬and AV-30‭ (‬see our preview in the October‭ ‬2019‭ ‬issue‭) ‬are lightweight‭, ‬affordable‭ ‬backup instruments‭. ‬The AV-20‭ ‬fits‭ ‬into a 2 1/4‭-‬inch hole while the AV-30‭ ‬has many more features and fits into a‭ ‬3 1/8‭-‬inch cutout‭. ‬For the tailBeaconX‭, ‬the AV-20‭ ‬or AV-30‭ ‬provides control‮—‬setting‭ ‬squawk codes‭, ‬sending an ident signal and managing modes‮—‬but also provides baro information‭ to the transponder.‬

uAvionix tailBeaconX installed
The tailBeaconX mounted in the expected location, where the taillight used to be. The unit is amazingly light and compact.

Install Notes

Obviously‭, ‬the tailBeaconX is intended to replace a conventional taillight‭, ‬like‭ ‬you’d find on thousands of Cessnas‭ ‬and Pipers‭, ‬as well as a bunch of RVs‭ ‬in the wild‭. ‬As with the tailBeacon‭, ‬it’s intended to be powered by the nav-light circuit‭. ‬And that was the brilliance‭, ‬so to speak‭, ‬of the skyBeacon and tailBeacon products‭: ‬They were close to‭ ‬straight swap-outs for the lights they‭ ‬replaced‭, ‬made even simpler because‭ ‬they didn’t need anything from the avionics inside the airplane‭. ‬

For a retrofit‭, ‬then‭, ‬the tailBeaconX‭ ‬will be a more complicated affair‭. ‬In addition to installing and setting up‭ ‬the AV-20‭ ‬or AV-30‭ ‬heads‭, ‬you’ll need to run a shielded pair of wires to the‭ ‬existing taillight‭. ‬For their part‭, ‬the‭ ‬AV-20‭ ‬or AV-30‭ ‬can be hooked up fairly‭ ‬minimally‭, ‬with connections only to‭ ‬power‭, ‬ground‭, ‬data and pitot/static‭. ‬A nice touch is that both units come with‭ ‬“industry standard”‭ ‬1/4‭-‬inch quick-release connectors for pitot and static lines‭. ‬The AV-30‭ ‬will accept other connections for GPS data right now and is‭ ‬expected to grow to include autopilot control in the future‭. ‬If you have a compatible EFIS‭, ‬then the install is a matter of running the data wires to the tailBeaconX itself‭.‬

AV-20 display transponder modes
The AV-20 display in attitude mode (left) and on the transponder page (right). All transponder modes are managed through this device.

I tested the Experimental-only version of the tailBeaconX in my GlaStar‭. ‬One complication‭: ‬It didn’t have a taillight‭. ‬In fact‭, ‬I’m not certain that even if it did‭, ‬that the tailBeaconX would‭ ‬have been happy there‭. ‬That’s because‭ ‬the GlaStar has a fairly stubby lower tail cone fairing that’s quite a bit over-hung‭ ‬by the aluminum elevator‭. ‬uAvionix‭ ‬says the unit wants a clear view of the sky for a good GPS position solution‭. ‬Um‭, ‬that won’t work‭. ‬Even if you don’t have a GlaStar‭, ‬it’s worth considering‭ ‬where your existing taillight lives in‭ ‬relation to metal parts that could block the GPS signal‭. ‬

The tailBeaconX inside the GlaStar tail cone—shining a light to nowhere, er, Bulkhead B.

For my application‭, ‬I mounted the‭ ‬tailBeaconX inside the GlaStar’s fiberglass tail cone‭. ‬Any concerns that the location would cause performance problems were disproved after my test flights‭. ‬The instrument itself shows NIC and‭ ‬NACp scores right on the face‭. ‬NIC is Navigation Integrity Category‭, ‬and ranges from 0‭ ‬to 11‭. ‬NACp is Navigation Accuracy Category for Position‭, ‬and also ranges from 0‭ ‬to 11‭. ‬In order to be considered functional‭, ‬NIC needs to be 7‭ ‬or greater and‭ ‬NACp 8‭ ‬or more‭. ‬In testing‭, ‬the tailBeaconX not only‭ ‬averaged above 9‭ ‬in flight‭ (‬and hit 8‭ ‬sitting in the hangar‭) ‬but the FAA PAPR reports showed no flags‭. ‬Likewise‭, ‬ATC had no issues with the transponder even‭ ‬at lower altitudes‭. ‬The tailBeaconX‭ ‬might be small‭, ‬but it had no problems getting the job done‭.‬

The User Experience

Obviously‭, ‬you’re going to interface with this transponder in an unconventional‭ ‬way‭. ‬For my flight testing‭, ‬uAvionix‭ ‬provided an AV-20‭ ‬head unit‭. ‬By itself‭, ‬it includes multiple clocks‭, ‬a backup attitude indicator‭, ‬a calculated angle‭-‬of-attack indicator and the new transponder interface‭. ‬The AV-20‭ ‬powers up on the transponder page‭, ‬which‭ ‬shows the squawk code prominently as well as NIC and NACp scores‭, ‬mode‭ ‬annunciation and other menu items‭. ‬It also powers up in the ALT mode‭, ‬so there’s really not much to do for a simple VFR flight‭.‬

To change the squawk code‭, ‬you first have to press both lower buttons at the same time‭. (‬Touching one or the other scrolls through the available screens‭.) ‬This step highlights the first squawk digit‭, ‬which you can change through‭ ‬the left-side buttons‮—‬it’s up to increment‭, ‬down to decrement‭, ‬one digit at‭ ‬a time‭. ‬Got it‭? ‬Then hit the right-side‭ ‬button to move to the next digit‭. ‬Press both lower buttons to accept‭. ‬

To change modes‭, ‬continue scrolling with the right button until the mode‭ (‬ALT‭, ‬ON‭, ‬STBY‭) ‬is highlighted‭, ‬then‭ ‬change it with the lower-left button‭. ‬When not in the digit‭- ‬or mode-setting process‭, ‬the upper left button tells the‭ ‬transponder to ident or‭, ‬with a long‭ ‬push‭, ‬to reset the squawk to 1200‭. ‬

This control scheme is logical but‭ ‬fussy‮—‬and not nearly as easy as using a traditional transponder‭. ‬Why‭? ‬It’s a small head unit‭, ‬none of the buttons is lighted and finding‭ (‬then pressing‭) ‬both buttons in the heat of turbulence simply isn’t as effortless as twirling knobs or jabbing a series of numbered buttons in sequence‭. ‬I appreciate the limitations of the small display and limited input choices‭, ‬but it’s still not an ideal interface‭. ‬

The AV-30‭ ‬head unit‭, ‬which was not available in time for this test‭, ‬has a lot more functionality than the AV-20‭ ‬and portends an‭ ‬easier time of it‭; ‬at least it has a rotary controller with a push-to‭-‬accept function‭. ‬I hope to update this story once an AV-30‭ ‬becomes available‭ ‬with the new transponder software‭.‬

The Bottom Line

Pricing for the Experimental-class tailBeaconX is‭ $‬2499‭. ‬uAvionix is currently offering bundle pricing, which makes the total $‬3194‭ ‬with the AV-20 control head‭ ‬or‭ $‬3794‭ ‬with the AV-30‭—that’s a savings of $200 to $300, depending upon the head unit chosen. ‬If you already have an EFIS that will talk to it‭, ‬this makes the‭ ‬uAvionix device a good alternative to‭ ‬remotely mounted Mode S transponders‭. ‬For example‭, ‬Dynon’s Mode S remote‭ ‬transponder runs‭ $‬2200‭ ‬but you’ll need some dedicated wiring for it as well as an antenna‭, ‬which is part of the tailBeaconX assembly‭. ‬It may also require a different‭ ‬GPS position source than you already‭ ‬have to be legal‭; ‬the tailBeaconX already‭ ‬has you covered with its internal GPS‭. ‬

The tailBeaconX is also‭ ‬less costly‭ ‬than Garmin’s GTX 345‭ ‬Mode S‭ ‬transponders that both have built-in GPSs‭, ‬though you also get ADS-B In features that neither the Dynon remote transponder nor the tailBeaconX offer‭. ‬And‭, ‬of course‭, ‬the panel-mount GTX 345‭ ‬is a stand-alone unit that requires no EFIS for control‭. ‬But for many new installations and retrofits especially‭, ‬the tailBeaconX is a terrific choice‭. ‬

For more information, contact uAvionix at 844-827-2372, or visit


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