Hi Alan,
Just a partial answer.
There are several different types of blocks.
FA, FR24, and the other public sites that also use official FAA data feeds honor blocking requests for aircraft owners that submit proof of ownership. That’s what the aircraft you saw did. The aircraft itself will still broadcast the correct mode-s code, which you can find on the FAA site for the registration. Anyone using a local receiver will receive and identify the aircraft just fine.
A year or so ago, the FAA started a privacy feature that only shows on the official FAA.gov registration page. Aircraft owners can choose to mask their name, address, and other personal details from that online page. If you look up an aircraft like this, the owner information will be completely blank. The rest of the aircraft details are still visible.
Corporations and others wanting FAA.gov registration privacy, and liability protection will often be registered as a corporation name or something like “N123 Flyers LLC”. That can hide the actual owner, but often private owners like that still use their home address, which doesn’t offer any privacy.
A few years back, the FAA started offering “SBS” blocking or obfuscation. With this, an aircraft requests a new, temporary mode-s code that does NOT identify their actual N-number tail. They program this code and then fly with it for a few months or so. When using the SBs code, you will visually see the painted N-number on the aircraft, but the transponder sends a mode-s code for the SBS identification. They also use a different voice callsign to hide the original identity.
You will receive a SBS mode-s code just fine. It will belong to an SBS N-number registration. If you look it up online at FAA.gov, it will show as something like “SBS program office”, so you know it’s a hidden ID. If you are able to match a visual N-number with a SBS mode-s code, then you can probably track that aircraft for a few months or so. The operator can use either the real mode-s code, or the temporary SBS mode-s code. Later, they can request a new SBS code. I don’t remember the exact timing, but I believe it’s a few months or so. Occasionally you will see an aircraft flying with an SBS mode-s code, but then incorrectly broadcasting their real “Flight ID” (normally N-number or callsign), which identifies the real aircraft. That’s a simple mistake on the transponder, and defeats the purpose of SBS.
Sites like adsbexchange will show SBS flights just fine, but make no attempt to do a matchup with the real aircraft.
If you’re curious, you can look up aircraft owner blocking on FA’s site. They explain how the owner requests it. You can also read about SBS at FAA.gov.
Reference aircraft in to Spokane. Remember that we are only talking about mode-s and ads-b aircraft. There are many military aircraft that fly mode-a/c only, even though they are ads-b equipped. Some even switch from ads-b to mode-a/c only during different phases of the mission. Mode-a/c position is much trickier, and you won’t be able to do anything with it on FA, FR24, or any of the more common big online sites.
You won’t see the mode-a/c only aircraft on the public sites, but you might occasionally see them when being rebroadcast as TIS-B by FAA ground sites using radar positions. The mode-s code for mode-a/c aircraft will be a pseudo code, and not actually identify the aircraft. I suspect your area likely has TIS-B and ADS-R rebroadcast. If you’re curious, you can search those terms and read about them.
Have fun watching. I think you are going to enjoy using adsbexchange and possibly some of the others that are similar.
Regards,
-Dan
