[Scan-DC] ADS-B Feeding

[dewey3 at gmail.com]

Thanks Jordan!

That was a mouthful, but it sure explains it.  There are four tracking site
that I am aware of, ADS-B Exchange, FlightAware, FlightRadar24, and
RadarBox, and your explanation solves the ADSBEx question.  Thank you for
showing how and where to expect the effects.

Dewey

-----Original Message-----
From: scan-dc-bounces at mailman.qth.net <scan-dc-bounces at mailman.qth.net> On
Behalf Of Jordan Hayes
Sent: Thursday, February 8, 2024 13:08
To: scan-dc at mailman.qth.net
Subject: Re: [Scan-DC] ADS-B Feeding

 >I wonder what affect this will have on ADSB-Exchange, the only website 
I am aware of that does not block "Blocked aircraft".

This issue is separate from the one that ADSB-Exchange eschews.

Any vendor that redistributes? resells? FAA-sourced data must block from 
retransmission any tail number or three-letter-code flight numbers which 
are on the LADD "block list" [ https://www.faa.gov/pilots/ladd ] -- 
examples:

https://www.flightaware.com/live/flight/TWY57 
https://www.flightaware.com/live/flight/N68885

These are the same aircraft. But of course ADSB-Exchange doesn't block 
them (because they don't get their data from the FAA, and thus aren't 
under the same rules), so:

https://globe.adsbexchange.com/?icao=a9247d&lat=37.355&lon=-121.927&zoom=5.0
&showTrace=2024-02-08

There's a *different* FAA program that allows an operator to change 
their Mode-S code to one that does not translate to a specific tail 
number; in order to still function correctly in the national airspace 
system, they further contract with a firm that manages 3-letter-codes 
for them, so that's what you'll hear on your scanner when they talk to 
ATC. Here's an example:

https://globe.adsbexchange.com/?icao=a1010e&lat=34.011&lon=-115.150&zoom=5.0
&showTrace=2023-10-04

You can see in the left column that the "DB flags" on ADSB-Exchange 
lists this one as PIA and links to this description:

https://www.faa.gov/air_traffic/technology/equipadsb/privacy/

And if you look up that code it translates to N164FG which has a funny 
looking "registration" record:

https://registry.faa.gov/aircraftinquiry/Search/NNumberResult?NNumbertxt=164
FG 


Anyway, on that day, that aircraft flew with a few different call signs 
(click on segments to see): The flight originated (back up one day) at 
Austin Executive (EDC) as XAA4644 to SNA; inbound to MRY from SNA was 
XAA3703; then it flew to Steamboat Springs as XAA2303; then to SNA as 
XAA1222; and finally back to St Louis (KSUS) as XAA9882. [XAA is the 
3-letter-code for ARINC and you'll hear ROCKFISH on the radio, much in 
the way you'll hear SPEEDBIRD for British Airways (BAW)]

That seems pretty airtight: unless you saw the aircraft on the ground at 
one of those airports, you'd have a hard time figuring out the tail 
number. I mean, it's not impossible to determine that it was actually 
FA7X N8200E, but it's pretty hard.

Anyway, the story linked to earlier just says that there's a few new 
places where you can continue to do this kind of thing; for various 
technical reasons routes over parts of the ocean weren't set up to 
handle it. You also can't, for instance, do it while flying 
internationally, because it's an FAA-only program: you have to put your 
real code in the transponder when flying to, say, London:

https://globe.adsbexchange.com/?icao=ab3338&lat=33.987&lon=-65.348&zoom=3.0&
showTrace=2024-01-17 


TL;DR: fewer flights will show on FAA-sourced sites like Flightaware; no 
change for ADSB-Exchange.

/jordan
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