FlightAware Discussions

Seeing Planes Visually that Don't Show up on ADS-B

I have an ADS-B receiver in Luck, WI, which is about 60 miles NE of MSP and 17 miles from the nearest other ADS-B receiver. I’m seeing (visually) a couple of GA aircraft each day which don’t appear on my piAware receiver.

I find it hard to believe that these aircraft are not ADS-B equipped. I suspect that they may have UAT. Is there a good option to add UAT capability to my receiver?

Yes. You will need a second dongle/antenna for 978MHz, then it’s just some minor configuration. You may want to consider running a second Pi for the second dongle as running two dongles off one Pi has a few challenges (both physically connecting two dongles, and also powering them reliably)

The “official” piaware docs for UAT are somewhat lacking but the forums are a good resource, here’s a starting point: Howto : Piaware SD card image 3.8.0 Quickstart Guide

I get the impression that with two dongles, you have two separate maps, one for 1090es and the other for UAT? Is there any way you can have a single map that shows all of the traffic?

This might answer your question. The map of user @wiedehopf is obviously capable to display both

It would be nice if FlightAware would provide a simple solution for a dual frequency receiver with a single map that showed all aircraft for those of us who are not technical gurus.

I think there is some confusion somewhere. Two frequencies require two radios.

What you are asking is equivalent to two car radios tuned to different stations piping into one set of speakers. I guess that could work, but Bach mixed with Metallica would be a mess.

Providing a single map for a two-dongle system is on the roadmap, somewhere.
We’re not actively looking at doing a dual-frequency board at the moment.

I can live with a two dongle solution. What I need is a simple turnkey solution on setting this up, with a single map.

I suspect that if you had this, a lot of people would upgrade their receivers to provide UAT coverage. Glad to hear that this is on your roadmap.

I recently added a UAT receiver and antenna. It works well on one Pi. TAR1090 shows both if you flip the flag in the config.

But note, I still get a random plane flying over once in a while that doesn’t show up on either. I’ve had this happen with low flying military helicopters lately. But I’ve seen it a few times with small GA aircraft as well. My MLAT works well, so not sure what’s up. They are not showing up on FR24 or FA either. So it’s not a problem with my station…

Have you heard of ModeC :slight_smile:
No MLAT for that.


Can you add a flag for that in TAR1090, thanks. :laughing:

While ADS-B adoption is quite high, it’s still technically only required in certain airspace; this can be best summarized as “near a busy airport” (ie one served by airlines). Someone living in a rural area and only intending to fly locally could get along just fine without ADS-B. There are also relaxed requirements for aircraft that were not originally certified with an electrical system; there are a lot of Piper Cubs and Aeroncas out there that fit this bill.

If you’re interested in the nuts and bolts and/or really enjoy reading federal statutes, FAR 91.225 has all the gory details.

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Thanks for the info. Makes a lot more sense than those conspiracy theories I was considering. And I do live on the edge of rural-ness.

Lots of military aircraft are also not yet ADS-B equipped.

ModeC isn’t even in the json coming from dump1090-fa, so not displayed in tar1090.
It’s only squawk + altitude, so it’s not interesting to look at either.

Sorry, I was attempting humor in my comment.

Which ones? What known is the fact that they sometimes turn it off.

I am living in range to Ramstein Air Base where the F-16 fighter located in Spangdahlem are often doing excercise flights.

They are all ADS-B equipped and visible as long as it’s niot disabled.
Sometimes i can watch F16 doing test refueling with a KC35.

Like this some weeks ago:

ADS-B transponders are usually not enabled often during workups, depending on the mission (OPs fall under another mode). They will be enabled for some of the more basic/nav ops, so will sometimes get a glimpse of what’s going on. This also depends on region. Some things don’t need to be publicized for obvious reasons.

I’m rusty in my avionics training but… it’s the same system that does all the Mode (123C4, etc)

And no, I’m not elaborating on the bracketed information.

You are correct, just different protocols, 1-3, 4,5 (IFF) vs. ACS. For the last year or so, military, DOD and other agencies can shut the system completely off due to security concerns.

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