ADS-B IN traffic

[RVDan]

I have the SV-470 for ADS-B in.  I generally have seen this to be very reliable in that if I see traffic outside, it is shown in the system.  Yesterday, while cruising at 7500 ft (I was flying KFDK to KITH (east coast)) and talking to NY Center, they called crossing traffic 500 ft above and 2 miles ahead (a Dash 8).  I had visual, then looked at the traffic display and no traffic is shown near me.  Nothing even close to being identified as the aircraft I had visual on.   The ADS-B status was all good.  Other traffic was shown, but not the aircraft that offered an immediate threat.  Center saw us, so our transponder was working well.

We know their transponder was working because Center could see them.  I know SV-470 depends on a ground station to repeat traffic info, and that I was receiving the ground station, as there was other traffic displayed.

No idea whether this was an ADS-B ground system failure or a failure of the Dynon system for some reason.

I don't have a screen capture or any other info at the time.  SW version 15.0.4.  Not sure what failed in the overall scheme of things so just reporting the event. 

 

[Dynon]

What was the actual ADS-B status message? Was it "ADS-B OK"?

 

[RVDan]

Yes it was ADS-B OK

 

[airguy]

I had a similar event this past weekend in Houston, "ADSB-OK" on my screen and had a bizjet cross in front of me at 3 miles and 1000' above - called out to me by ATC and in visual, but nothing on the screen. I know there are "issues" with the 472 unit and Dynon is working on that, so I just chalked it up to that issue.

 

[mrdaud]

Another data point. Flew from eastern NC to eastern TN last Sunday at 8,500'. Was in a 2 plane flight flying about a mile apart, with the other plane a Cirrus. Saw the Cirrus as traffic, but 3 or 4 times he just disappeared off the screen for several minutes, then showed up again. Flight following said he saw both of us on radar just fine when this happened. The Cirrus traffic EFIS was solid for traffic the entire trip. Several other traffic icons would also disappear, then come back during the flight. As far as I remember, the ADS-B was showing "OK".

 

[Raymo]

Keep in mind that airplanes that do not have ADS-B out will not reliably show on your screen. Your plane with OUT will trigger a broadcast from the ground station but it will only include aircraft within a certain distance from you.

Sounds like the Cirrus should have shown for you, though. Did it have OUT installed too?

 

[RVDan]

Keep in mind that airplanes that do not have ADS-B out will not reliably show on your screen. Your plane with OUT will trigger a broadcast from the ground station but it will only include aircraft within a certain distance from you.

Sounds like the Cirrus should have shown for you, though. Did it have OUT installed too?

Referring to the OP, I have the Dynon ADS-B OUT and so therefore should have had traffic at all times. Besides when the one target was missing from the display, there was other traffic displayed.

 

[mrdaud]

It wasn't that I wasn't seeing traffic at all, it was just intermittent. The Cirrus was full out/in and was seeing all the traffic all the time. I know this because I was talking to the Cirrus and ATC. The other intermittent traffic was commercial traffic from Greensboro and Raleigh which was well within the reporting distance and altitude.

 

[N11VX]

Flying in Southern Ca, I see a lot of traffic and will intermittently see targets disappear and, sometimes reappear minutes later--all while ADS-B OK. It's better than having no awareness, but something isn't quite right with the system somewhere between the traffic, ATC, and the system in my plane.

-Randy

 

[ChiefPilot]

Flying in Southern Ca, I see a lot of traffic and will intermittently see targets disappear and, sometimes reappear minutes later--all while ADS-B OK.  It's better than having no awareness, but something isn't quite right with the system somewhere between the traffic, ATC, and the system in my plane.

I see this frequently as well, using different hardware entirely. It's a problem with the ADS-B design as a whole, which is why it's advisory only.

I *regularly* see C-130s in and out of KMSP, for example, hanging on a string just a few miles ahead of me and perhaps 1000' above me. They cross over the top of my home drome (KSGS) when using 30L/R into Minneapolis. They *never* show up on my ADS-B display, although there are always Delta, Skywest, and other traffic in the vicinity with their data blocks and altitudes.

My experience is that if ADS-B thinks there is something there, there is something there. If ADS-B doesn't think anything is there however, better look because it might be wrong. In other words, the absence of a traffic alert doesn't mean there is no traffic...