You are right, Shorrick. But since 2011 ADS-B in & out has been under test with some airlines and Eurocontrol. Seems as if airliners younger 5years are capable of what you can find here:
We probably have 10+ percent of the fleet equipped in the US with some kind of ADS-B Out. The centers now have some of the data feeding their fused sources, but the TRACONs don’t have it yet. Regardless, a good percent, probably 50% would not qualify as usable for surveillance purposes and the data would be rejected and not forwarded to ATC. It will only accept the position reports from TSO C154c or C166b, the SDA and SIL values as well as the NACp, NACv, and NIC must all meet the criteria for use.
probably 50% would not qualify as usable for surveillance purposes
Is there a flag in the data packet which indicates the level of GPS the data came from?
And if ATC won’t use it, who can use it?
It certainly can’t be used at all for airliner TCAS (the one with resolution advisories, mutually negotiated between the two systems).
The various versions of 1090ES out and about self identify the RTCA DO that they comply with. Only those that comply with RTCA DO-260B may be used by ATC. SDA is a value set usually by the manufacturer of the ADS-B Out capable transponder. SIL includes configuration information entered by the installer and takes into account the availability of integrity data from the GPS source. In cases where a simple GPS position is provided, the interface from the GPS usually does not also provide the dynamic values of NIC, NACp and NACv, so the transponder sends nothing in these fields. This is another dead giveaway. Also the simple position sources do not provide a geometric altitude (AKA GPS based on WGS84), another clue you are dealing with a bogus GPS position. In the US, we also have UAT non transponder based ADS-B Out and these have to match the transponder code and pressure altitude emitted by the transponder. So it is not usually difficult to spot and ignore a bad system. A TSO ADS-B In device has to also ignore systems that have bad values.
Most of the air carriers that have ADS-B Out have version DO260A and some have the very old DO260 versions.
And if ATC won’t use it, who can use it?
FlightRadar24, and all the GA traffic advisory systems, like PowerFlarm ?
The current thinking at EASA seems to be that they want as many airspace users as possible to radiate ADS-B positions, even with SIL/NIC/NACp 0. While you cannot use such an ADS-B broadcast for separation, you can still use it for situational awareness, i.e. a traffic display.
OK… I am trying to get my head around why anybody bothers to radiate ADS-B at all, compliant or not.
Obviously they are not doing it for charitable reasons i.e. to support a million plane spotters watching FR24 
What is the legislation which mandates the installation? Presumably airliners (Part 25 or whatever classification is used) have to do it.
But then why radiate the noncompliant sort? What equipment can display it?
Specifically, should Avidyne ever get around to upgrading the firmware of the TAS boxes to accept ADS-B, will they discard the noncompliant targets?
While you cannot use such an ADS-B broadcast for separation, you can still use it for situational awareness, i.e. a traffic display.
Doesn’t that mean that in the ATC regulatory scenario, ATC will in practice not be allowed to use this at all? They can’t just rig up a laptop with FR24 on it, can they? I know they do at some smaller places (in the UK you have to pay c. GBP 100k/year for a radar feed) but they have to hide it when they have any kind of inspection.
In France no ATC uses ADS-B except in:
Ajaccio due to lack of radar coverage below 4000 ft (I’m not sure if it’s operational or for advisory purposes)
Remote area such as Tahiti, New caledonia, French Guiana…
ATC will in practice not be allowed to use this at all?
Those EASA people I spoke to in Friedrichshafen think they will and push into this direction.
There’s a NATS supported project going on to explore low cost low power ADS-B position emitters.
The current thinking at EASA seems to be that they want as many airspace users as possible to radiate ADS-B positions, even with SIL/NIC/NACp 0. While you cannot use such an ADS-B broadcast for separation, you can still use it for situational awareness, i.e. a traffic display.
A TSO device can’t display a target with SIL or SDA of 0.
What is the legislation which mandates the installation? Presumably airliners (Part 25 or whatever classification is used) have to do it.
But then why radiate the noncompliant sort? What equipment can display it?
Specifically, should Avidyne ever get around to upgrading the firmware of the TAS boxes to accept ADS-B, will they discard the noncompliant targets?
See https://www.eurocontrol.int/articles/information-aircraft-operators My understanding is that the European mandate has been pushed off to 2020. It applies to aircraft that are above 12500 pounds or an IAS of 250 Kts. See http://easa.europa.eu/agency-measures/docs/agency-decisions/2013/2013-031-R/Annex%20I%20to%20ED%20Decision%202013-031-R.pdf for technical details.
Here is the EU regulation document: http://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32011R1207&from=EN
ADS-B has been around for some time and many air carriers have voluntarily equipped with the earlier versions. Airbus and Being have been equipping new production aircraft with the compliant version, but most airlines have not done much retro fitting as of yet. The US 2020 mandate is driving much of the equipage.
Regarding the Avidyne system, it will support both active interrogation and in the future it is supposed to support ADS-B In. It will undoubtedly be certified under the same TSO as is required for ADS-B In and will not display ADS-B targets sourced from devices with a SIL/SDA of zero, but these targets will still be displayed as transponder targets using the TAS function, so they don’t disappear unless their is a non compliant ADS-B Out and no transponder on the target aircraft. Non certified systems such as many in the US use, for example ForeFlight/Stratus would display such targets on an iPad.
A TSO device can’t display a target with SIL or SDA of 0.
If I understand that correctly, that makes non-TSO ADS-B radiation a waste of time unless one has a tablet mounted somewhere to display the traffic.
No panel mount device will display those targets – unless they are non-transponding, but how many of those who are radiating ADS-B will be non-transponding.
