Bogus traffic indication?

[jdubner]

Can someone explain the (apparently bogus) traffic indication I saw yesterday?  This is from a 10-inch SkyView and SV-XPNDR-26X in an area where I normally don't normally receive traffic info via TIS.  It lasted only a few seconds.

 

[dabear]

This occurs in all systems (dynon and non-dynon) that use the FAA feed for traffic. I've seen it when the system thinks I'm a ghost (It is telling me about myself).

 

[DonFromTX]

For us not yet flying with our Skyview, I THINK I am seeing a bogus aircraft at your altitude and position. What I cannot understand is why it would be showing a course 90 degrees from yours? (or am I just reading it wrong)

 

[jdubner]

This occurs in all systems (dynon and non-dynon) that use the FAA feed for traffic

Thanks, Bear.  I didn't see anything about it in the Pilot's Guide but I agree: it is my aircraft. 

I THINK I am seeing a bogus aircraft at your altitude and position.  What I cannot understand is why it would be showing a course 90 degrees from yours?

That's how I see it too.  And I also do not understand the 90-degree different course although I was in maneuvering flight and that data may be a little old.

But it really gets my attention when "traffic" pops up at my altitude :-(  It's rather disconcerting; wish it could be "filtered out" or otherwise suppressed.

 

[Garrett]

It is a bug in the FAA's TIS traffic system that has been there since the system's inception. I does not matter who's equipment is installed in the aircraft. It just intermittently happens.

 

[dynonsupport]

This user is using TIS-A, which does have the ghost issue the most, especially when you first log in to TIS, and it is trying to correlate all the targets.

The vector isn't that interesting either- this report may have been from the very first time the radar swept you, so the estimate of your direction will be off until it gets a few more sweeps on you- of course that will also get it to correlate you with yourself and will remove you as a TIS target as well.

It's unfortunate, but it is the way TIS-A works. All we do is display the targets the ground radar tells us to. I think we all wish they had implemented a more robust initial correlation to remove these false alerts. It seems exceedingly unlikely that on the first sweep of a radar on a new target there would be two targets colliding at that very moment.

 

[jdubner]

Dynon's response and explanation is very reasonable.

Can I assume that someone with ADS-B traffic does not have this issue, even with the mode-S transponder? (I'm planning to add the Dynon ADS-B module someday.)

Perhaps a small blurb in the SkyView Pilot's User Guide is merited. (I searched for "traffic" and did not find this phenomena mentioned.)

Thanks,
Joe

 

[dynonsupport]

If you really want the details on TIS, check out the AIM:

http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0405.html

This does still occur with ADS-B at times as well, albeit less often than with TIS-A.