How does ATC use ADS-B?

[dwurfel]

This is not a criticism of ATC. I have alot of respect for all of them and have helped save my skin a few times. My question though is how does ATC particularly centers use ADS-B for flight following or IFR tracking. For illustration I was flying VFR through the first mountain range West of Pueblo CO. I was not at the MEA but at a safe altitude ( 12,500 ) for the valleys I was flying through to get to Buena Vista CO. I had picked up Flight Following from Denver Center in the flatlands. ATC told me they had lost me on radar and to SQAK 1200. ADS-B reception/transmission is very developed in the Colorado Rockies. My thoughts are ATC could easily track me on ADS-B even if I was sitting on the runway back in the mountains. Wandering why ATC continues to use radar exclusively and not use ADS-B as well. Somebody set me straight. Thanks as always for all the help this forum has provided to me.

[Rich]

I assume you have ADS-B out in your plane.

I too, am confused, as we are told around here that if we squawk 1200, ADS-B presentation is suppressed on ATC screens. So we’re requested, when in the vicinity of DSD (25 nm) to monitor center and squawk 1237. This makes us visible to them AND states we’re monitoring 126.15. This allows them to initiate direct requests to our N-number so to initiate conflict resolution. This does work.

Otherwise ADS-B feed to their scopes is suppressed. I have no clue why this would be.

[dwurfel]

Rich, I was flying IFR MEA in remote Arizona and asked Center if they had me on radar and ADS-B. They replied they had me on radar but they had to go through a number of items to get to ADS-B so it was a passive system basically. I love it in my Diamond but also wondering if all the things that the FAA advertised to happen have.

[Soareyes]

I too, am confused, as we are told around here that if we squawk 1200, ADS-B presentation is suppressed on ATC screens. So we’re requested, when in the vicinity of DSD (25 nm) to monitor center and squawk 1237. This makes us visible to them AND states we’re monitoring 126.15. This allows them to initiate direct requests to our N-number so to initiate conflict resolution. This does work.

Probably not pertinent to the subject but, where is DSD? I haven't heard of this alternate VFR squawk in the areas I usually fly.

[Rich]

I too, am confused, as we are told around here that if we squawk 1200, ADS-B presentation is suppressed on ATC screens. So we’re requested, when in the vicinity of DSD (25 nm) to monitor center and squawk 1237. This makes us visible to them AND states we’re monitoring 126.15. This allows them to initiate direct requests to our N-number so to initiate conflict resolution. This does work.

Probably not pertinent to the subject but, where is DSD? I haven't heard of this alternate VFR squawk in the areas I usually fly.

DSD is Deschutes VOR, just SW of Redmond, OR. This is a local procedure to deal with a special local problem. KRDM has a class D with a fair amount of airline and other traffic. DSD is really close to the SW boundary of that class D. It is on a number of airways, provides the only VOR approaches around here, and is also the initial/final missed approach fix for a number of instrument approaches. There is also a lot of VFR flight training and other flying into/out of 5 other public use and several private-use airports nearby that frequently causes conflicts with the various flight paths into KRDM. Yes, we're all "entitled" to do whatever in that class E airspace. This is a modest request from ATC to help them out with no real hardship to us.

The bad news is this procedure is not well-known, even among local pilots. It was published in a Letter To Airmen and does not appear as a NOTAM, in the chart supplement, or anywhere else a pilot would be expected to look.

[Colin]

I toured the LA TRACON facility and asked this very question about ADS-B on their scopes. They said they turned on the feature when it was first installed and there were ALL sorts of targets that didn't match the radar targets. In particular, there were a bunch on approach into LAX where they were talking to a plane when a target would pop up in front of that plane. Even though they were pretty sure it was a ghost they had to call it out as traffic. I think he said the feature was turned on for four hours and has been turned off since.

[DaveS1900]

This is right off the FAA Website, it looks like it is up to the local controllers to decide if it is displayed.
Dave S.
Ohio


ADS-B Out equipment transmits information about the aircraft's location, ground speed and other data once per second. The broadcast includes the aircraft's unique ICAO address, which for a U.S. registered aircraft is associated with its tail number, and the Mode A code ("squawk" code). The signal also includes the aircraft's flight ID, which for GA aircraft is generally the registration "N" number, or for commercial/government operator's, their call sign or airline flight number. Air traffic controllers can immediately see this information if they desire, however the controller has display options where they can suppress the N-number for VFR aircraft that are not receiving flight following services. Additionally, GA operators that are equipped with UAT transceivers, squawking 1200, and flying below FL180, have the option to select "anonymous mode". This enables the transceiver to broadcast a randomized flight ID and pseudo-ICAO address, but it disables ATC's ability to provide services. The transceiver reverts back automatically to the assigned ICAO address and default flight ID when the anonymous mode is turned off.

[CFIDave]

I learned that it's up to individual ATC Centers and TRACONs (and perhaps individual controllers) whether they choose to display ADS-B information on their scopes.

Where I live on the US east coast, most controllers don't use ADS-B. But when I was delivering a brand new DA40NG and flying cross-country across the state of Kansas, Kansas City Center ARTCC noticed that when tracking our aircraft via our 4-digit transponder squawk code, our ADS-B Flight ID didn't match our correct tail number that was included in our filed flight plan. (It turns out that Diamond misconfigured the ADS-B Flight ID before delivery.) So Kansas City Center *was* displaying and using ADS-B information.

I've been told that so many transponder ADS-B installations have this same problem (i.e., incorrectly configured Flight IDs) that most controllers have been forced to turn ADS-B on their scopes to "off."