A question from the under-educated:

What does a GDL82 or Skybeacon/Tailbeacon transmit if the master transponder is turned off after an initial VFR squawk? For example, after flying out of over-controlled airspace, xpdr is switched off intentionally.

Legally, one can not turn off the ADSB-out post January 1, 2020 but can one simply turn off the transponder to accomplish the same result?

(Note this does not apply to me. I have gone Mode-S width adsb-out)

mtv wrote:…..No, ADS-B is NOT the same as the transponder rule. Read the respective rules!
The transponder rule says the transponder, I’d installed must be ON at all times when operating in controlled airspace. The ADS-B rule doesn’t exempt the uncontrolled airspace. And that’s where a lot of the problems with this stuff is happening: in Class G airspace.

Transponder rule FAR 91.215 https://www.law.cornell.edu/cfr/text/14/91.215

"(c) Transponder-on operation. While in the airspace as specified in paragraph (b) of this section or in all controlled airspace, each person operating an aircraft equipped with an operable ATC transponder maintained in accordance with § 91.413 of this part shall operate the transponder, including Mode C equipment if installed, and shall reply on the appropriate code or as assigned by ATC, unless otherwise directed by ATC when transmitting would jeopardize the safe execution of air traffic control functions."

ADS-B rule FAR 91.225 https://www.law.cornell.edu/cfr/text/14/91.225

"(f) Each person operating an aircraft equipped with ADS-B Out must operate this equipment in the transmit mode at all times unless -
(1) Otherwise authorized by the FAA when the aircraft is performing a sensitive government mission for national defense, homeland security, intelligence or law enforcement purposes and transmitting would compromise the operations security of the mission or pose a safety risk to the aircraft, crew, or people and property in the air or on the ground; or
(2) Otherwise directed by ATC when transmitting would jeopardize the safe execution of air traffic control functions."

motosix wrote:A question from the under-educated:

What does a GDL82 or Skybeacon/Tailbeacon transmit if the master transponder is turned off after an initial VFR squawk? For example, after flying out of over-controlled airspace, xpdr is switched off intentionally.

Legally, one can not turn off the ADSB-out post January 1, 2020 but can one simply turn off the transponder to accomplish the same result?

(Note this does not apply to me. I have gone Mode-S width adsb-out)

That is an interesting question. I don't know. I suspect it continues to announce ads-b as there is no reason for it not to. Perhaps what you are really asking is if it will stay in anonymous mode...

-0-

It will not squawk a “mode” but instead will squawk your ICAO info and the FAA may send you a letter or call you to let you know your system is messed up. Anonymous mode is off the table and it shows that the GDL failed due to not receiving the requisite info.

Thanks to Hotrod180 for the tip about using the test position on your transponder to help with the Uavionix setup, (and possibly maintaining anonymity during startup). I am based at an airport within a mode C veil but was not getting any interrogations to ping my Narco AT-150 transponder while on the ground, and pushing my Maule to the end of the hangars to get a straighter line of site to the tower didn't help. I got my tailbeacon a week ago and have encountered some challenges with installation that I thought I'd share, since the few videos and support documents on the internet don't yet seem to provide a very direct path to a successful Maule install. Here's my tips:

Best document about installation (on an experimental): https://pointsforpilots.blogspot.com/20 ... n-and.html

None of the online videos or installation instructions I saw clearly described the use of the Molex Permaseal crimp tubes, they work amazingly well with the correct ratchet style crimper (unidirectional, make sure you identify the crimp side vs the insulation side of the splice) and a heat gun to shrink the protective covering. All of the videos I saw skipped the sealing part... I've always preferred soldering and heat shrinking my electrical connections but those Permaseal connectors have changed my mind.

My Maule used different screws to hold the original position light on the rudder... pan head sheet metal screws that were larger than #4 and smaller than #6. The tailbeacon mouting base requires flathead screws, and with a fabric covered rudder I was hesitant to open it up to install nutplates for the provided machine screws. I wasn't confident that there was enough substance to the rudder skeleton to tap the existing holes, so I scoured the internet and found two suppliers that sold #5 stainless steel flathead sheet metal screws in quantities of less than a thousand. McMaster Carr and Ebay both had solutions. I ordered some 5/8 and 3/4 inch long ones but after trial fitting the unit realized there was some fabric interference with the end of the tailbeacon unit in the Maule's rudder (M6-235).

I called Uavionix and asked if they could send me three or four more of the self adhesive gaskets to use as a spacer, and they had five of them in my mailbox in two days at no charge (Bozeman to KC). Four stacked together was perfect.

The flight test required for completion of the FAA's rebate process generated a private ADS-B performance report that was in my email inbox within minutes of filing the request online. I had a 6.25% failure rate in the Mode 3A section under "Other Checks" , after setting my altimeter threshold at 32 for the initial flight. This was based on some incorrect assumptions on my part that older transponders need lower threshold settings than newer ones. I believe the recent units ship with a setting of 35. The Uavionix app allows adjustment from 25-45 (there's a hidden unlock option if you swipe right on the setting bar that accesses the extremes of that range) . Everything I'd read suggested lowering the setting by 3-5 if you were getting the 3A failure or not getting a squawk to show up on the app's monitor.

I ran back out to the hangar after reading the above tip about self pinging with the test position on the altimeter. This worked great with my Narco AT-150 and allowed me to quickly check the squawk performance. I got no response when working down from 32 to 25, and was starting to doubt that my test function was actually generating a squawk response. But as I worked up from 32 I started to see the 1200 code at a threshold setting above 39, but lost it again at 43 and higher. 42 proved to be the most consistent for my setup, so I guess older doesn't necessarily equate to weaker when it comes to transponder output. The opposite sounds true in some cases.

I'm hoping to repeat the test flight tomorrow with clean results. It looks like a chunk of my rebate will be going toward gas for the flight testing, and it sounds like it's not necessarily a "once and done" performance evaluation. Pilots have reported receiving certified letters of noncompliant ADS-B out flights from the FAA, so getting the transponder connection dialed in correctly for your specific aircraft seems to carry more importance than I expected (it's a little less plug-and-play than anticipated). My A&P had experience with skybeacon installation on his own aircraft, and that encouraged me to choose the Uavionix option. The company also has a Qualified Installer program available. Uavionix support has been outstanding, even in the fourth quarter of the game.

Just because you get a “clean” PPR after installation, don’t assume you won’t still receive a phone call or email from the FAA down the road after you’ve made a number of flights. Mine came four months after the unit passed the verification flight.

There’s not much you can do other than go fly, though.

So far, the fed ive dealt with has been helpful and professional.

MTV

I've encountered two red flags on my own & a buddy's Tailbeacon flight tests:

1) under "missing elements", "flight ID".
Uavionix tech guy told me it was because I hadn't allowed the txp/encoder enough warm-up.
Made sense, engine was already warm so a short 100' taxi & immediate takeoff.
I made sure to allow more warmup time my next try & it passed.

2) under "other checks", "mode 3A".
Tailbeacon was not picking up the txp signal.
We turned the threshold down & verified the tailbeacon was reading the txp via the test switch trick.
Passed on the next try.

Hope this helps.

Did a second flight today in the mode C veil, after tweaking the threshold to produce the most consistent squawk recognition on the app using the test switch on my AT-150. My first flight, with threshold set at 32, yielded 6.25% Mode 3a failures, and today's second flight, optimized for squawk recognition on the ground with the app, yielded a 100% Mode 3a failure at what "seemed" to be the best ground setting of 42. Apparently the optimal setting for my Maule on the ground without the engine running is not necessarily the best for consistency in the air.

Waiting to hear back from Uavionix support on which direction to go, I'm guessing maybe 30 then 35, seems silly everyone has to repeat these test flights to sniff out the best threshold value for their own plane. I guess I've got two flights out of the way of the possible twenty settings between 25 and 45. There is an automatic setting option if you swipe right on the threshold selector, but I haven't heard if its functional.

kcblade wrote:…..I guess I've got two flights out of the way of the possible twenty settings between 25 and 45. There is an automatic setting option if you swipe right on the threshold selector, but I haven't heard if its functional.

As I recall, my app only has a scale of 30 to 40 on the threshold,
comes pre-set at 35.
Don't remember seeing an auto threshold setting,
I'll check that out later today.
Tried here at home but apparently the app won't even open unless there's a skybeacon / tailbeacon turned on nearby.

Tailbeacon PIREP

After completing our changeover from floats to skis Friday I was cleaning up the tools, ladders, etc. By the time I was done, my mechanic had the Tailbeacon installed and configured. 15 minutes.

I flew the test flight yesterday per Uavionix instructions. Let everything warm up for 5 min prior to takeoff. 20 mins in ADS-B coverage area(no Class C, veil, etc necessary). No steep or prolonged turns. Landed, submitted report; received a clean report card via email within 20 minutes. Cessna 180.

As a bonus, the LED tail light is very bright. I'd definitely recommend this unit.

Maybe not applicable to your flight, but FWIW I believe your flight must include 30 minutes in "rule airspace" to qualify for a rebate.

The LED nav light is indeed bright.
I just wish uAvionix had incorporated a strobe feature into the Tailbeacon as they did with the Skybeacon,
or else a flashing nav light feature.
Hopefully they'll upgrade the software sometime in the future to include that.

Thanks, I was unable to get a rebate slot and therefore the test flight requirements are simpler.

Yes, I'd prefer the tailbeacon had a strobe. However, I just saw a Skybeacon strobe for the first time. It is not as bright as the modern standard LED flashers, Whelen, Aeroled, etc.

hotrod180 wrote: As I recall, my app only has a scale of 30 to 40 on the threshold, comes pre-set at 35.
Don't remember seeing an auto threshold setting,
I'll check that out later today......

At the hangar now, just checked the app.
As i recalled, mine shows a threshhold range of 30 to 40.
It does have an auto threshhold feature,
you have to swipe the threshhold section over to the right.
It says that in order to use it, your txp must be interogated (by radar or by test equipment) at least once per second.

Swipe right and you get an automatic setting detection option, swipe left and you can unlock the expanded range of 25-45. When I ran the automatic setting option while running on the ramp, it suggested a threshold of 37. Today I did three more flights, at 30,35,and 37. Previously flew at 32 and 42. All failed. I'll try and post a plot of my five data points, I'm not very encouraged by how this curve is looking though. The Uavionix support portal ticket I submitted yesterday seems to have fallen into a crack in the internet, so I'll give them a call tomorrow. Starting to think about that Appareo Stratus ESG. Calling the fuel truck twice in one day is no bueno. Thanks for the help!

35, 37, and 42 were wasted flights.

Go down to 27.

Curious,

Is anyone having issues with the 335 and 345 transponders? My 345 has no issues since installed 6 months ago.

Kurt

G44 wrote:Curious,

Is anyone having issues with the 335 and 345 transponders? My 345 has no issues since installed 6 months ago.

Kurt

I had a 335 installed in my old 170 about 5 or 6 years ago.... never had any issues at all.

G44 wrote:Curious,

Is anyone having issues with the 335 and 345 transponders? My 345 has no issues since installed 6 months ago.

Kurt

You wouldn't expect a 1090ES solution like the 345 to have issues because it doesn't need to sync up to an external transponder in any way. It really is the best ads-b solution from the perspective of simplicity and reliability, but it's missing anonymous mode, so the FAA knows where your airplane is at all times.

I posted on VAF this morning and a guy that has been testing this replied with some useful information:

.....the GDL-82 WILL stay anonymous outside radar interrogation if its pin 5 is grounded. It seems to do its own transponder interrogation to see your baro alt and 1200 code outside ATC radar. If it sees 1200 and a grounded pin 5, it remains anonymous.

That is very interesting. It means that the Garmin really is anonymous.

He also wrote:

I just used my scanner and avare adsb recorder on Skybeacon TSO with 1.4.0 current software and the Anonymous mode performance is unchanged.

Startup is not anonymous.

Once in ATC radar contact with 1200 code, reply lights and anonymous mode selected, the id changes from N# to VFR.

Turn off transponder (lose 1200 replies) and 1 minute later real ICAO # and N# rebroadcast.

That tells me that the Garmin GDL-82 and echoUAT are the only solutions that are truly anonymous. The Garmin because it interegates the transponder to verify VFR squawk, and the echoUAT because it can verify VFR squawk over serial.