Installing an ADS-B GTX-45R with Avidyne TAS 600 Traffic

[Rick]

Sorry for the thread drift, guys. Getting back to TRAFFIC... Like Don and others, I also have both TAS600 and ADS-B traffic, and I get both on the MFD, at the same time. You can tell the difference by the symbol used to display the traffic. Usually I only see ADS-B traffic symbols, but occasionally a target shows up with the old TAS symbol. I assume those targets are not ADS-B out and are also not being rebroadcast by any ATC station. Somehow the GTX345 is smart enough to not show a duplicate TAS symbol when it has ADS-B information for a target, but it shows a TAS symbol when it sees something out there that it doesn't know about via ADS-B.

[greg]

Interesting. Working from memory, the traffic target deduplication happens inside of the GTX345 where the TAS output is input into the GTX before the G1000 ever "sees" it. Assuming my memory is correct, you shouldn't be able to select between the traffic systems as the G1000 only has the output from the GTX as its input.

Agreed that the traffic aggregation "should" happen in the GTX, and not the G1000. It's just that in my case, it doesn't work. The input from the TAS600 into the GTX can be disabled by a configuration setting in the GTX (no idea how as I don't have the configuration software), and that was the only way they could get the GTX to work properly.

I wouldn't discourage the OP from going ahead, since my experience seems to be very atypical. But I don't understand why it should be so hard to diagnose - I assume all the signalling between the TAS and GTX would be digital, which shouldn't be that hard to get right.

[MarkA]

I also have an ADS-B GTX345R installation scheduled in November for my 2010 XLS.

I believe the document you want to look at is attached. It describes the G1000 changes introduced when a GTX345R is installed including how ADS-B and TCAS traffic are merged and displayed and how to select ADS-B or XM weather data source.

GTX 3X5 Series Transponder G1000 Pilot's guide 190-01499-01_A.pdf

(351.81 KiB) Downloaded 103 times

[smoss]

Clarification for everyone on the TAS "old" symbols that show up with integration. These are usually NOT actual targets from the TAS600, but rather non-ADSB targets being rebroadcast via TIS to the GTX without directional info or tail number. After getting mine installed, I spent considerable time figuring out how to tell of the setup is actually working. It is more difficult than it sounds... While foreflight tells nothing of the target origin, nor does the G1000, Garmin Pilot in fact tells you a breakdown of all the sources of the targets, as well as an individual target source if you click on it (ADSB and type, TIS, or TAS). The G1000 merely shows a tail# and directional info if available (ADSB or ADSBR), or a diamond with no # if TAS or TIS. The GTX prioritizes its "merging" of targets with ADSB being clearly its first choice of source, then apparently TIS, and lastly TAS. So consider you are in a radar coverage area, flying next to a plane with no ADSB--in this case you would see either a diamond or an arrow (depending on radar source sophistication) with no tail number, but the source is actually TIS, not the TAS600! Using Garmin Pilot, if you click on that target, it will show TIS as the source. So the only way to actually see a TAS source target is to go to an area with no radar coverage, and fly next to a plane with no ADSB. In this situation, you will see the diamond, and if you click on it in Garmin Pilot, it will show TAS as the source. Surprisingly, there are very few remaining areas not covered by radar. Outside of Las Vegas, there is a small area low and behind a mountain that is dead zone. I did this experiment with my friend in his non-ADSB plane, and sure enough, his target showed on my Garmin Pilot as TIS all the way to the radar dead zone, then changed to TAS once there. Save for that tiny area, there are essentially 0 radar free zones at normal flying altitudes in Nevada, California, Arizona, or Utah that I have found, so 99.99% of the time, the "old" style targets are from TIS for me, not my own TAS600. Even over the middle of the Sierras, or in the middle of nowhere central NV, there is good radar coverage, and typically ADSB tower reception. The one time you will see a few TAS targets is right off the ground after takeoff in a busy area with non-ADSB planes around. For literally just a few seconds (until you are high enough to pick up an ADSB tower and then get the TIS traffic) you see may see a few. When I was testing this a lot, I would catch it, but now, by the time I raise the flaps it is picking up a tower with TIS now the prevailing source. While I personally would not recommend Garmin Pilot for actual flying, (ForeFlight is much more user friendly), should anyone wish to verify or play with the traffic integration stuff, Garmin Pilot is indispensable. One more oddity to mention is that for some reason that neither ForeFlight or Garmin can explain or figure out, ForeFlight does not always display 100% of the targets seen on the G1000 or Garmin Pilot. My interpretation is that ForeFlight is not receiving the "merged" traffic from the GTX, but rather only the ADSB/TIS data relayed to it. I spent quite some time talking with ForeFlight and Garmin trying to figure this out, screen shots and all, with surprisingly little understanding on their end of how any of the stuff is actually programmed to work or how to remedy. None the less, at least a few times, we would see a very close target on the G1000 that was not displaying on ForeFlight, despite all the other targets showing up (so presumably not a Bluetooth issue).

[Rich]

Foreflight does show the source if you click on the target. It'll show something like 1090ES or 978 UAT or TIS 978 and whatever information it has on the target. I don't have TAS so I can't comment on what it might show in that case.

There are radar blind spots around here in mountainous areas even at not-scary-low altitudes. Around pattern altitude here at Prineville non-ADSB targets will appear and disappear, depending on where they are in the pattern. Remember also that there is very often significant latency as to the position of these targets. Many radars have 12-second sweep times. Actual ADSB planes are within a second.

Of course aircraft with no or inoperative transponders or flying with them turned off are invisible to all our electronic systems. There also seem to be some old Mode A units, where ATC says something like "altitude unverified".

[smoss]

Rich, you are correct that ForeFlight shows 1090Es, 978 UAT or TIS--I had forgotten. It never showed any TAS for me, never saw a single one via "clicking" on targets, that's when I bought Garmin Pilot to play with it more as there is a whole page that shows where the GTX target sources are originating from. I remember the first time I saw a TCAS target show up there, I was quite excited it was actually working. But in practical flying, the TCAS targets as a source are almost non-existent now in the GTX setup. In retrospect, it wasn't worth the extra time and money to integrate it, vs just tossing it and saving the weight / improving CG. Another difference, not mentioned before, is the GTX traffic alerts occur only under very close calls, as opposed to how the TAS600 would alert when it was in control. The TAS seemed to give aural alerts on a regular basis to me. The GTX now only gives them when you are really about to imminently run into someone, and almost never less than 1,000 AGL. Its sensitivity varies based on what part of flight you are in--so in the pattern, or landing for example, the alerts are very inhibited vs at cruise.