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01-28-2019, 01:14 PM
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Join Date: Jan 2005
Location: Dallas, TX
Posts: 171
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ADS-B traffic picking up birds?
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.
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Clay R- RV9A - Flying since 2004 - 400 hours
VAF dues paid through end of 2020.
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01-28-2019, 01:21 PM
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Join Date: Jan 2005
Location: SC
Posts: 12,887
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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.
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Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
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01-28-2019, 04:06 PM
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Join Date: Nov 2013
Location: Prescott, AZ
Posts: 1,613
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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
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"Kindness is never a bad plan."
exemption option waived. Donation appropriate.
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01-28-2019, 08:58 PM
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Join Date: Jun 2007
Location: Atlanta
Posts: 743
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So----I guess its OK to use my Navworx after all???  |
01-29-2019, 07:52 AM
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Join Date: Oct 2009
Location: Victoria, BC, Canada
Posts: 3,926
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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?
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Rob Prior
1996 RV-6 "Tweety" C-FRBP (formerly N196RV)
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01-29-2019, 08:04 AM
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Join Date: Mar 2006
Location: Newport, TN
Posts: 7,496
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Quote:
Originally Posted by Snowflake
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?
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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. |
01-29-2019, 08:14 AM
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Join Date: May 2006
Location: Pocahontas MS
Posts: 3,884
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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?
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01-29-2019, 08:25 AM
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Join Date: Mar 2006
Location: Newport, TN
Posts: 7,496
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Quote:
Originally Posted by rv7charlie
Do the ADSB towers retransmit primary (negative transponder) targets?
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I have never been able to get a definitive answer to this question... I sure would like to know. |
01-29-2019, 08:49 AM
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Join Date: Mar 2010
Location: KSGJ / TJBQ
Posts: 2,034
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Quote:
Originally Posted by Brantel
I have never been able to get a definitive answer to this question... I sure would like to know.
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No it does not and you can read it on the FAA ADS-B FAQ, ADS-B IN section. The only "primary RADAR only" data available on ADS-B are some ground vehicles while you are the ground on a few very large airports.
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Galin
CP-ASEL-AMEL-IR
FCC Radiotelephone (PG) with Radar Endorsement
2020 Donation made
www.PuertoRicoFlyer.com
Last edited by GalinHdz : 01-29-2019 at 08:54 AM.
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01-29-2019, 10:57 AM
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Join Date: Aug 2006
Location: santa barbara, CA
Posts: 1,680
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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
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