ADS B ghost traffic. Garmin GNX 375

I’ve had this installation in my 170B for about six months and it works flawlessly. The other evening I took off and it reported traffic alert but did not talk, just lit up the screen. Showed it to be 100 feet below me in the same place. There was nothing there. Leaving the other airport later it did the same. Next day, worked flawlessly again. WX was VFR on all occasions. Normally it calls real traffic audibly “TRAFFIC. 11 O’Clock. Same altitude. Less than one mile” for example. I was below 500 feet on take off both times.

Question, is there some outside influence like atmospheric conditions or GPS glitch that would cause this?

Rich

Seeing itself?

Web

I can't speak about the Garmin GNX375. I can tell you to be very careful before you react to a traffic signal. My scary incident at LAX was long prior to ADS-B, using airline equipment. My system got very excited telling me to climb to avoid traffic. It hadn't even seen the other airplane approaching. I did not climb because I had just seen the traffic slide over the top of me. Shortly after that "climb" call it changed it's mind telling me to dive. I turned left and there was the traffic right where I would have hit it if I had followed the initial instruction even if I climbed a very small amount, right on my wing tip in the bank.

Web,
Pretty sure it was seeing itself, but I was wondering why as it had never done it before and hasn’t done it since. I have heard of this happening with other devices like Sky Beacon once in a while but there never seems to be a good explanation. Why yesterday and not today?Different satellites on different days? Right after take off maybe the GPS WAAS data was lacking?
A mystery of life I guess.

Pete, I always look for the traffic and find it most of the time.

The live tracking program Flightrader24 will on occasion report double images of the same aircraft. That's around Fairbanks AK. so maybe it's the receivers having a disagreement about position?

Edit: I assume with potentially multiple receivers there's some sort of "voting algorithm" that decides which position data to accept.

Gary

My hangar partner talked with me earlier this week about a "glitch" ATC was reporting with his aircraft on his last two flights... They are seeing double "mode-c" altitude reports, 100 ft apart with his tail number associated with both, and co-located on their radar screen. They kept asking him if he was a flight of two...

This wasn't ADS-B data they were receiving, but the actual Mode-C data from the "standard" squitter broadcast from his transponder. The separate ADS-B data block was there as well (and correct, by the way, since it uses a separate encoder for the UAT module). He has an appointment with an avionics shop scheduled to get it fixed...

My non-educated, scientific wild-ass guess is that his encoder is going bad, and alternating (cycling rapidly) between two altitudes instead of "averaging" the pressure readings and reporting either one or the other. It will be interesting to learn the actual resolution.

I have KT74 and it sees itself on occasion. Anecdotally more often when turning.

This may be anecdotal “Fighter Pilot” evidence that if one flys a tight enough circle then you will disappear up your own.....[emoji4]


Sent from my iPhone using SuperCub.Org

I watched a LJ45 fly from Bethel to Anchorage AK. this morning....double image shown on Flightrader24. Not saying it's the same deal as the false traffic here but something's odd.

Gary

I've seen the same thing and I think what is happening is the what I am seeing is the same target, whether ourselves or others, because I am near a tower broadcasting the TIS traffic data, at a delay, due to the built in network delay. Flying out of range of the ground station, I only see direct aircraft broadcasts so only one target.

There are two issues going on when I took this image. First the In is showing my airplane as a ghost target and secondly it is displaying my N number when I have the anonymous mode switched on. It stayed like this for maybe as long as 5 minutes.

The gps is a Garmin 796 being fed by a Garmin GDL 52, the transponder is a Becker and the Out system is a Garmin GDL 82.

I just installed a GNX 375 in my 182. And now every time i fly i get a text from my buddy who is tracking me on flight aware. How do i mask my N number with the 375? The manual isn't very clear. I am hope i can go Anonymous. I don't like Big Brother watching me all the time. Thanks for you help.

You can file a block request with the FAA but it won't keep your info off most internet tracking sites. Welcome to the reality of ADS-B.

https://www.ainonline.com/aviation-...018-02-14/few-answers-ads-b-security-concerns

Anonymous mode is only available with the UAT ADS-B Out devices. Your Garmin 375 is a 1090ES device, so no "anonymous" mode.

FWIW my own airplane shows up on the ADSB display on my tablet from my Stratux "in" device.
The altitude is usually "-125'" or similar.
If my Tailbeacon is set in anonymous mode, it either shows just the altitude or sometimes "VFR" plus the altitude.
If not in anonymous, it shows the tail number also.
I'd like to not have my "own ship" show up at all,
but I've messed with the app (Avare) settings, and the stratux setting,
and haven't been able to prevent it.

Also FWIW, I've gone online & gotten an ADSB performance report about once a month
since I installed the Tailbeacon about a year ago.
When it's in anonymous mode, sometimes I get a report that says no flight was detected.
But other times, I am detected & do get a report.
Go figure.