ADS B traffic question

[laytonl]

I have a GDL 88 and today my airplane popped up as a threat to me. The target stayed with me for most of the trip today. Attached is an image of Foreflight and you can see the aircraft identifier from the ADS B. What's causing the system to report itself as a threat?

GDL 88

GNS 530

Lee

[Bob_Belville]

Lee, in more than 2 years flying with the GDL 88 (w 750) I have had this "shadow" effect happen only once. I was flying from Lancaster PA to Acton MA and the boogie stayed around for 40-50 miles over Wilkesbarre PA into NY. Someone here explained in terms of a ground station but I do not remember the details.

[Andy95W]

Since you were on Foreflight, does that mean you were receiving the traffic alert on a Stratus? Or also through the GDL-88?

[Piloto]

When you see yourself is traffic data coming from a ground UAT station. The UAT reports all traffic in your area including yours. It puzzle me that it show you as -100ft below when it should be 00ft. You were probably in a climb. Check on the Foreflight manual for your own echo rejection. Maybe all you need to do is to enter your plane tail number somewhere.

 

José 

[FloridaMan]

I've had this happen with my Xaon unit a time or two. Try moving the receiver. Also, I noticed it was happening in the vicinity of clouds; I think I was picking up my own echo at times. 

[laytonl]

I failed to mention I saw this on both Foreflight ( with 1st gen Stratus) and on the GNS530W (using the GDL88). Transponder is a 330S.

Lee

[Bob_Belville]

I experienced it, just one time, on GTN 750. (My xponder is a GTX 327.) The "traffic" was converging at the same altitude from my left and passed right through me approximately over the Wilkes-Barre vortac then diverging as I traveled northeast for several more miles.

[N601RX]

Next time it happens look and see if it has your plane listed under ownership. See attached. This is with 978 out and a stratus 2.

[Piloto]

Lee what may be happening is that you have two sources of ADS-B Out That are causing your own traffic to show. The GDL-88 is showing traffic from the GTX-330ES and the Foreflight is showing traffic from the GDL-88. Try turning off the GDL-88 or the GTX-330ES, it should make a difference.

José

[laytonl]

Thanks guys. It didn't happen on a flight today, so maybe it was just an odd fluke. Lee

[1964-M20E]

My IFLY 720 used to do it seems they may have changed something since I have not seed it recently.

[Ftlausa]

This happens to me periodically as well.  It is disconcerting and has caused me to take evasive action -- until I see the threat is following me as I maneuver. 

[Marauder]

I have seen this a number of times on my Garmin GDL-39. Scares the crap out of you the first time you see it. 

[Bob_Belville]

I have seen this a number of times on my Garmin GDL-39. Scares the crap out of you the first time you see it. 

To say nothing of the traffic paranoid wife/copilot.

[jnisley]

This happened to me last fall while skirting around Chicago's class bravo airspace, I opted to go VFR because of Chicago Center being out of service so I was already nervous with all the traffic in the area. Wow, my heart almost ejected until I figured it out!

[Piloto]

Pop ups are not rare on ADS-B but they could easily be real traffic that just climbed to ATC radar coverage. One way to recognize real traffic is to momentarily set your transponder to NO ALT. If the indicated traffic shows no altitude or goes away it is then your own plane.

 

José