Garmin Pilot Full TIS-B Traffic and Ownship Detection

[Bob - S50]

One more thing you might check, although probably not the issue.  I don't remember where, but either in the GDL39 or Garmin Pilot settings, there is a setting concerning use in pressurized aircraft.  If you can find it, make sure it is set for an unpressurized aircraft.

[AaronDC8402]

I haven't adjusted that setting at all (at least not intentionally). I do plan to try turning it off and on though on my next flight just to see if it makes any difference.

 

[AaronDC8402]

Finally made a little headway with Garmin on my issue. I've been communicating via email with Garmin tech support, and I've also tried calling a couple of times. The guy I've been emailing with basically gave up on me, and suggested I take up the issue with an avionics shop. After getting that email, I called again. Now that I know my specific issue (altitude reference for traffic display not correct), Garmin phone support was much more helpful. 

I didn't have the GDL with me when I called, but the guy suggested that I have a problem with my barometer in the GDL. He told me how to view the pressure altitude that the GDL sees (Connext >> Situational Data >> bottom of the list). I got a chance to check that this morning. Sure enough, it's reporting negative FL201 while on the ground. The GDL has an internal barometer, and it seems to only be used as a reference for traffic display. 

My temporary work around is to activate the "pressurized cabin" setting. That forces the GDL to use geometric position (GPS) for altitude reference instead of the barometer.

The next step is to call Garmin again to figure out if anything can be done about the barometer. I'm not sure if it's faulty or out of calibration.

[Marauder]

Since we are talking about TIS-B, I think this is an example of Garmin Pilot showing full TIS-B on my GP because I was in someone's "hockey puck" (plane in the lower right) and as soon as I lost him, I lost TIS-B. Still have no explanation of the new target that showed up at the exact time I lost TIS-B. Some mysteries still exist...

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[cnoe]

Still have no explanation of the new target that showed up at the exact time I lost TIS-B. Some mysteries still exist...


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The new target was below you and climbing. Perhaps he was squawking ADS-B Out the whole time but his antenna was under his belly and shaded. Once your planes approached closer altitudes his signal was unmasked? Just a guess.

I've been "out" compliant for 3 years now and have seen plenty of weird traffic stuff over that time. I LOVE having the full traffic, but no way do I trust it entirely!

[AaronDC8402]

I was still under warranty for the GDL39, so Garmin issued a RMA. I'm expecting a new GDL in about a week. Hopefully that fixes everything.

 

[AaronDC8402]

The new GDL came in last week. Tonight, I finally got to go fly around with it. The ownship detection is working correctly, and other aircraft's relative altitudes are reporting correctly. Unfortunately, I didn't pick up any ground stations (probably due to flying low - sightseeing). Hopefully, once I'm flying at altitude, the TIS-B traffic starts showing up too.

 

[AaronDC8402]

Another update. Finally got the plane up to altitude yesterday with the new GDL in it. I'm now getting full TIS-B traffic. Everything is working as expected. 

Conclusion: The baro sensor in the GDL had failed. The discrepancy between the baro alt and geometric alt (GPS) caused the issues I was having.