Is the FAA even seeing ADS-B traffic?
 

Okay, I upgraded my Garmin 330 transponder to a 330ES a couple months ago. It's connected to a 430W with the latest software upgrade and should be now fully compliant. So far it's been really great. I'm displaying traffic on both the 696 GPS and iPad using the Garmin Pilot app. I can now see most of the traffic as it is triggering the ground stations to send the traffic up to my GDL-39 receiver to display. And my friend Randy, who flies next to me in his RV-8 frequently, also gets the benefit of seeing more traffic using his GDL because he's within my 15 mile hockey puck. When the traffic is shadowed behind hills from radar I'm not seeing them as expected.

In Oregon we have quite good ADS-B ground station coverage. I only lose it flying at low altitudes around hills. I recently discovered a cool website http://planefinder.net. What's interesting about this website is that you can see current air traffic, or you can go back in time and look for traffic at a specific time. So I've went back to a time when I know I've been flying and found my tail number scooting across the screen. Yes, big brother is watching our every move. What I don't get, is that it appears that I'm only seeing actual radar tracks and not any ADS-B position reports. If I go too low and am shadowed by radar then my track drops off the screen. When I'm talking too low it could be 3000 feet or higher but shadowed by radar. That's typical for this area with all the hills. In these cases I could guarantee that I probably had reception from at least three ADS-B ground stations at that location and altitude. I've checked multiple flight tracks and it's the same story for all of them.

Recently I made about a 45 minute flight using flight following. Seattle Center at one point said they didn't have me for a little while at 4500 feet because that was an area that I'd need to be a little higher. That in fact was an area where you could expect that to happen if you didn't have ADS-B. But it's an area of solid, multiple ADS-B ground station coverage. When I did see my radar track it did display tail number, altitude, speed and squawk code. I'm assuming that was probably info they received from my transponder direct to the radar site. Probably the same info they'd get from any TIS transponder.

So my question, is the FAA really seeing any ADS-B traffic? Or is our ADS-B position being sent to the ground stations and that's where it stops? The ADS-B is doing the job of triggering the ground station to send traffic images up, but it's like my position never makes it into the system via ADS-B. Could it be that we have until 2020 to upgrade because it may take them that long to figure out how to view our position and integrate it with the existing radar? Maybe ADS-B is only a benefit to the pilots today.

I'm far from an expert at the links between ADS-B ground stations and your local radar facility, but it is my understanding from talking to a lot of experts on ADS-B that the links are not there yet and thus ATC doesn't use ADS-B out at all yet, except maybe in a test area or two.

They need to build out the ground infrastructure first, and then they will upgrade the links to ATC facilities.

It's much more a benefit to pilots (WX and traffic) than ATC right now.

And FYI, planefinder is a private website and service, not a link to any FAA database of radar tracks.

--Ian Jordan
Dynon Avionics

Planefinder also relies on a network of volunteer folks to feed them the ADS-B data from their home receivers and computers. If you are out of range of one of these volunteers, you won't show up as an ADS-B target.

I have not dug into the TIS-B specs hard enough to determine what part of the system isolates one's own aircraft from the data stream. I suspect that it is the airborne receiver that decides which target is itself but I am not sure.

I have never seen a false target on my G3X system being fed data from the GDL39.

Yes Bruce, I have experienced exactly the same thing many times. You think you have traffic right on top of you but it's your own airplane. I normally get this when I'm out practicing commercial maneuvers like lazy eights where I have a sudden change of direction. I had this same thing before when I was only using TIS only before I added the GDL. That issue was better when I turned off the TIS in the 696 setup. The 696 still gets ADS-B without the TIS on. I turned the TIS back on because I actually get more traffic on the 696 with it turned on in the Portland area. There's traffic I don't see on the iPad with the GDL only that I see on the 696. Explain that one.

I'd respectfully disagree that sites like planefinder are not tapped into the FAA radar feed somehow. If you zoom out they display traffic all over the world. There's no way a little private network could capture all that traffic or have their own radar sites. And per my previous comments they are obviously are not displaying my ADS-B signal. The tracks on that site match exactly what I've experienced in the area using flight following with radar coverage shadows.

If the FAA really isn't using our ADS-B data yet I hope the marketing groups from ADS-B equipment suppliers don't try to sell equipment based on promises of us being seen better if we put that equipment in our airplanes. At this point it sounds like it would only help us been seen by the few other ADS-B equipped airplanes. But the current benefit for me is still worth it.

Mark,

The FAA air traffic is seeing and using ADS-B for separation in some areas. The ADS-B only has to perform as well as the current RADAR for coverage to be commissioned. After commissioning, the ads-b still has to be integrated into air traffic facility operation. Some of the central US has yet to be commissioned. All ads-b commissioning was terminated in March, due to the budget cuts. Commissioning will resume at some point.

I have seen this same thing while doing maneuvers such as steep turns during the 4 1/2 years I have been flying with the GTX-330 and TIS-B traffic. I just completed a panel upgrade from Cheltons to GRT Hxr. I installed the Radenna Skyradar D-2 for ADSB in on both 1090 and UAT. I also had my GTX-330 upgraded to the ES for ADSB out. Now I have a full time "own ship" target riding along with me. :mad: The interesting thing is that this "own ship" only shows up on the Hxr traffic display, and not on my 430W TIS-B traffic display. So, I guess it must be coming from the Skyradar receiver, which is wired directly to the Hxr via USB cable. GRT is working with me to come up with the "fix" for the problem and I am confident we will get it worked out.

THe GTX-330 cannot receive TIS-B even when upgraded to the ES version. It receives TIS....there is a big difference in TIS and TIS-B. TIS is only available in certain terminal areas and is being decommissioned. TIS is notorious for slow updates and ghost targets. TIS-B is much better and can be received anywhere there is a ADS-B ground station in range as long as you have compliant ADS-B out data either with a UAT or an ES enabled xponder.

My mistake! Thanks for explaining the difference to me.

If you are getting TIS services from a Mode S xponder, you very well may be getting better traffic when it is working verses the GDL-39 if you do not have a compliant ADS-B out solution onboard. Unless you have a UAT or an ES enabled xponder transmitting properly formatted data, you won't see the full power of the TIS-B services.

TIS services are well known to have slow updates and ghost targets. TIS-B is much better in this regard.

Planefinder and FlightAware and all those similar sites do have some sort of access to the FAA's system of radar data. Most if not all of them at this time that are reporting ADS-B enabled traffic are doing it by using a network of volunteer's with ADS-B receivers on the ground connected to their computers/Internet. There are many gaps in their coverage and if an ADS-B enabled plane does not show up, it might be in one of those gaps. Most of these sites are actively recruiting volunteers to host a receiver site. Some of them will even send you free gear to get a site up and running.