Silvaire wrote:
I suspect that the 75% ADS-B OUT equipped number quoted above for the US must apply to flights on a flight plan,
That is my number estimate. I assume there are 200,000 aircraft of US registry. The latest data from the FAA shows that 147414 aircraft have been equipped, 147414/200000 = 74%. The FAA monitors the ADS-B broadcasts and that is where they get their numbers from, not flight plans. 14059/147414 or 10% of the aircraft that are installed are not yet compliant with the rule. Most of these are installation setup issues or non compliant position sources. These pilots get letters from the FAA to get their equipment fixed.
NCYankee wrote:
ADS-B Out or a transponder is not required, even for IFR flight, as long as one remains below 10000 MSL and outside of B and C airspace.
Below 10,000 feet and outside of rule airspace, which for Class B has a volume several times larger than the lettered airspace it surrounds. For those of us operating around Class B the distinction continues to matter – it cost me $3K or so.
I suspect that the 75% ADS-B OUT equipped number quoted above for the US must apply to flights on a flight plan, flights using flight following, planes on FAA radar or some other subset of all the aircraft extant in the US. It’s certainty a high number that the FAA would like to promote but there are airports by my observation where likely not one aircraft is equipped, or perhaps just one. It’s a big country and most of the planes never go anywhere near rule airspace. On the other hand, it has become fairly easy to equip if the plane has a Mode C transponder – with a skyBeacon, a logbook entry, a test flight, an FAA performance report via the website, another logbook entry and submission of an A&P IA signed form 337.
FlightAware and other competitors have a link to the FAA, that is where they get the flight plan route information from and radar data from. ForeFlight uses FlightAware for its traffic feed. To use the traffic data, one has to agree not to display information on FAA blocked tail numbers. Without the FAA traffic feet, one will miss a significant number of flights. ADS-B Out equipage is roughly 75% of the fleet (90% of which is compliant), about 10% of the fleet are only primary targets, no transponder and no ADS-B Out, The remaining 15% is transponder equipped, but almost all Mode A/C. ADS-B Out or a transponder is not required, even for IFR flight, as long as one remains below 10000 MSL and outside of B and C airspace.
Many thanks NCyankee for looking into it.
Would FR24 really have a link to the FAA, rather than picking up just radiated signals?
Dimme wrote:
Flightradar24 doesn’t care about ATC. It receives signals on 1090 MHz and displays them.
No way for mode A/C transponders, there is no identification other than the transponder code which is not unique. Mode S can be detected by MLAT or ADS-B can be detected on 1090 MHz if the aircraft is equipped. About 25% of US aircraft don’t have ADS-B of any sort and of the remaining aircraft that are ADS-B equipped, about 20% use 978 MHz. ATC provides radar feeds if the vendor agrees not to provide tracking information for blocked aircraft.
Flightradar24 doesn’t care about ATC. It receives signals on 1090 MHz and displays them.
Unless they have a link to the FAA which is probably likely.
Dimme wrote:
They don’t have to be. A separate device can still emit Mode S (ES) with a Mode C transponder installed on the aircraft, or no transponder at all.
That would not be allowed in the US.
Dimme wrote:
So was that a retransmission by ground stations that the FR24 receivers picked up?
The flight plan was tagged up by the ATC computer with the wrong N number based on a controller error. ATC sees a fused target which consists of radar returns merged with ADS-B and Multilateration. The controller would probably have also seen a Flight ID mismatch indication.
NCYankee wrote:
All transponders in the US are not mode S
They don’t have to be. A separate device can still emit Mode S (ES) with a Mode C transponder installed on the aircraft, or no transponder at all.
NCYankee wrote:
a mode A/C transponder only replies with altitude and squawk code
That why this link doesn’t report any squawk code, it’s not a transponder: https://www.flightradar24.com/data/aircraft/n113ac#25bb409b
NCYankee wrote:
I called the pilot and ATC got his N number wrong. His transponder was setup correctly and later in the flight he corrected ATC. That is why there is a duplicate record, one for N113AC entered by ATC for the flight and the other tracked by his actual ADS-B Out broadcasts, which was for N413AC.
So was that a retransmission by ground stations that the FR24 receivers picked up?
I called the pilot and ATC got his N number wrong. His transponder was setup correctly and later in the flight he corrected ATC. That is why there is a duplicate record, one for N113AC entered by ATC for the flight and the other tracked by his actual ADS-B Out broadcasts, which was for N413AC.
Peter wrote:
I thought Mode S was not big in the US anymore…@ncyankee may know more about this.
N113AC has a hex code assigned of A0375B
N413AC has a hex code assigned of A4DF48
The aircraft in question is a 2019 SR22 which has only an ADS-B Out via a Mode S/ES transponder, so the transponder itself would have to have the incorrect N number entered into it.
Peter, if you wish, I can most likely contact the pilot to have him check.
Actually about 80% of the ADS-B installations in the US use 1090ES which uses a Mode S transponder. The other 20% use mode A/C and a UAT based ADS-B Out.
Current numbers for ADS-B equipped aircraft as of 10/1/2020 is 147,414 aircraft, 14.059 of which are not compliant.Dimme wrote:
All aircraft with a transponder emit Mode A/C/S.
ADS-B out is simply Mode S with more data on-top (Extended Squitter), which may actually be provided by a completely separate device like a uAvionix tailBeacon or SkyEcho 2.
A misconfiguration in that second device would show up like what happened in your case.
All transponders in the US are not mode S, it is not required and a mode A/C transponder only replies with altitude and squawk code. In the US, ADS-B Out may be based on a mode S transponder with ES or can be using a UAT ADS-B Out system that is separate from a transponder. In my aircraft, I have a mode S transponder and a separate GDL88 UAT based system. Many have UAT based systems and a mode A/C transponder.
