Somebody in the US yesterday with my Mode S config:
No defence at all Peter, because you are well known to make silly long trips
I suspect this being some kind of ADS-B out device, since the squawk remains at 0000 throughout the flight. Probably one of those the owner can configure on his own?
Exactly as I suspected. I found the culprit: N413AC
ADS-B out: https://www.flightradar24.com/data/aircraft/n113ac#25bb409b
Mode S: https://www.flightradar24.com/data/aircraft/n413ac#25bb2af0
Exactly the same path, same time, very similar callsign.
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.
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.
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.
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?
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.
