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ADS-B traffic picking up birds?

ClayR_9A

Well Known Member
Patron
I recently installed a GRT Safefly/uAvionix Echo UAT in my plane so I now have traffic on my GRT EFIS.

It is taking a little getting used to what I should expect with this system, as there have been times where I've seen airplanes but no indication of them on screen, and also have seen traffic on-screen, but could never find the airplane out the window.

This weekend, I saw a target in front and to the left of me about 100ft lower about 3 miles away. The target did not have an N-number, and it was coming and going on the display - not consistently displaying. As I got closer and closer, I was starting to worry, because I couldn't find the airplane, and it also didn't seem to be moving in any particular direction. Then, right where I expected to see a plane, I saw 3 turkey vultures circling in a thermal at about 2000'.

Now, unless the vultures are carrying transponders now, I don't know how ATC Radar would have been able to determine their altitude, or even see them at all... unless radar can see individual birds and determine altitude without a transponder in some cases. I understand some radar can, but thought ATC radar isn't supposed to be able to do that.

Has anyone else seen targets that they suspect were birds, and not aircraft?

Funny, I know.. but I have to ask.
 
Not birds but I have seen planes with working transponders not show up on my SkyView ADS-B or be called as traffic by ATC.
 
SHHHHHHHHHHHH......

Those vultures work for a three letter govt. group. Don't be tellin no strangers they are equipped.... The cartel doesn't know about aviaries and such. YET
 
It's possible you were seeing aircraft that had transponders but not 1090ES transponders. It's my understanding that you'll only see the 978 equipped aircraft if they are rebroadcast from a ground station, so you may have been on the edge of one of those towers' range?
 
It's possible you were seeing aircraft that had transponders but not 1090ES transponders. It's my understanding that you'll only see the 978 equipped aircraft if they are rebroadcast from a ground station, so you may have been on the edge of one of those towers' range?

My understanding is that the uAvionix Echo UAT has a dual band receiver. If it does, he should be able to get both 1090ES and 978 UAT equiped targets via air to air.
 
According to a friend who's a retired FAA tower controller, the terminal radars can see 'birds' (no definition of how big/how many) up to 30-40 miles away. Do the ADSB towers retransmit primary (negative transponder) targets?
 
From the FAA FAQ:

Q: Does TIS-B broadcast primary radar?

A: For tracks that are initiated with secondary radar, TIS-B will update the track if there is a momentary loss of secondary and only the primary is available. For surface service volumes, TIS-B uplinks primary-only tracks because vehicles operating on airport surfaces may not be equipped with transponders or ADS-B Out.

I suppose that means primary radar (no transponder signal) does not normally get transmitted, although it doesnt definitively say that. The explanation about the exception for surface vehicles because they may not be equipped with transponders is hokey since there are also some air traffic that isnt so equipped, and clearly it would be very helpful to see such traffic.

So I guess the bottom line is that non-transponder equipped aircraft wont usually show up as traffic? Thats disappointing.

Erich
 
For tracks that are initiated with secondary radar, TIS-B will update the track if there is a momentary loss of secondary and only the primary is available.
This "coast" track will only be available for a few seconds, then the entire track is dropped.

So I guess the bottom line is that non-transponder equipped aircraft wont usually show up as traffic?
You are correct.

:cool:
 
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So, It sounds like "non-transponder aircraft/birds" won't show up in the traffic feed at all.
 
From FAA FAQ: Does TIS-B broadcast primary radar?
For tracks that are initiated with secondary radar, TIS-B will update the track if there is a momentary loss of secondary and only the primary is available. For surface service volumes, TIS-B uplinks primary-only tracks because vehicles operating on airport surfaces may not be equipped with transponders or ADS-B Out.

A great geek out read. UND area study. Seems 10% of the time, even under ATC radar coverage by 2 stations, ADSB Altimetry errors can be reported up to 500'.

5 MB, 14 page pdf

https://www.google.com/url?sa=t&sou...FjAOegQIARAB&usg=AOvVaw1tfAGXI4lTSKvanAv5zlxx
 
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