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Is There a Technical Reason to Include N Number in 1090ES Broadcast

Toobuilder

Well Known Member
We know that UAT has an "anonymous" mode - and presumably this strips out the N number from the broadcast when sqwawking 1200. Is there any technical reason why 1090ES does not offer this option?

I think ADSB out is fantastic. I also understand the importance of broadcasting relevant performance and configuration data about my airplane, but I can't understand why the system needs my registration data at all times. I don't mind being a target on a screen, but I do not like being a "specific" target. And based on this poll, I'm in a huge majority.

It seems to my uneducated brain that a bit of software in the transponder would simply "turn off" the N number part of the broadcast when the unit is set to 1200. Is there something I'm missing at the other end that "requires" a valid N number in the broadcast?

I'd like to start leaning on the AOPA to advocate "true" anonymity for 1090ES if it's technically possible, but stopping by here as a first step toward technical enlightenment if it's not.

I'd also ask that we not go down the familiar philosophical rabbit hole of privacy in a modern world. It's clear most of us want it, so let's find out how to have it from a technical standpoint.

Basically, can 1090ES function without broadcasting an N number or Hex address?
 
We know that UAT has an "anonymous" mode - and presumably this strips out the N number from the broadcast when sqwawking 1200. Is there any technical reason why 1090ES does not offer this option?

I think ADSB out is fantastic. I also understand the importance of broadcasting relevant performance and configuration data about my airplane, but I can't understand why the system needs my registration data at all times. I don't mind being a target on a screen, but I do not like being a "specific" target. And based on this poll, I'm in a huge majority.

It seems to my uneducated brain that a bit of software in the transponder would simply "turn off" the N number part of the broadcast when the unit is set to 1200. Is there something I'm missing at the other end that "requires" a valid N number in the broadcast?

I'd like to start leaning on the AOPA to advocate "true" anonymity for 1090ES if it's technically possible, but stopping by here as a first step toward technical enlightenment if it's not.

I'd also ask that we not go down the familiar philosophical rabbit hole of privacy in a modern world. It's clear most of us want it, so let's find out how to have it from a technical standpoint.

Basically, can 1090ES function without broadcasting an N number or Hex address?

My understanding is that 1090ES always broadcasts N-number because the specifications for Mode S transponders, and the international agreements on their use, require the registration to be broadcast at all times.

From a purely technical standpoint there's no reason 1090 systems couldn't work like that, but it would likely take a lot of modifying TSOs, ICAO agreements, and the like to allow it.

I can't back it up right now, but I suspect that Mode S (and later, 1090ES ADS-B) were expected to only be present on large commercial aircraft and business jets. I think the FAA simply assumed "little airplanes" would use Mode C (and later 978-based) systems.
 
The Nextgen ATC updates have included aircraft ID being transmitted from the aircraft so that controllers automatically have the data displayed on their scope tags without having to manually enter the data. This requirement was harmonized among the ICAO community first as a part of Mode S, then ADS-B. Further the general idea is for support of ADS-B In, TIS-B to allow other aircraft identify which aircraft shown on the traffic display was which. This will be especially helpful for when ?in trail? operations are approved in the future. For those who may not know, the goal is to have aircraft space themselves in VFR or IFR based on TIS-B traffic depictions, for operations where you are trailing another aircraft on approach.
I actually find it quite nice to be able to see the other aircraft ID so I can get the whole picture when listening to controllers give clearances to aircraft around me. Having an aircraft ID is a safety enhancement in areas with traffic, even around your local airport.

The whole snag became when ATC track data was made available to the general public. Not sure the how or why of that, but it happened.
 
The cargo part 121 that bought Apollo used to have the original merging and spacing hardware in part of the fleet.

It does not work that well. I grew up flying heavy formations. It is not perfect enough to just train up lightly.

Its research still burns tax dollars, but I don't think it is near.

It's last real use was 3 nights in 2010...
 
The S in mode S stands for ?selectable?. The idea was this: Sometimes two targets at the same radar azimuth and distance but different altitudes could have their transponder replies overlap and interfere. With mode S ATC can select one transponder and tell it not to reply next time, and then address the other and tell it not to reply on the subsequent sweep. To ?address? the transponder, it has to have a ?name?. The obvious name is its N number. It won?t work as envisioned without a name.
The obvious solution is the simple one. At one time the FAA posted airmen?s social security numbers all over the internet. It took some time, but now most of them are gone. It really shouldn?t be so hard to make the N number database private, for the simple reason that there?s no compelling reason for it to be public.
BTW, I have a different interpretation of the poll. I?d say that the overwhelming number of readers are so indifferent that they can?t be bothered to respond.
 
The S in mode S stands for ?selectable?. The idea was this: Sometimes two targets at the same radar azimuth and distance but different altitudes could have their transponder replies overlap and interfere. With mode S ATC can select one transponder and tell it not to reply next time, and then address the other and tell it not to reply on the subsequent sweep. To ?address? the transponder, it has to have a ?name?. The obvious name is its N number. It won?t work as envisioned without a name.

The other aspect of mode S is the ability of it to provide a data link to threat aircraft with TCAS II, which provides resolution advisories. The resolution advisories are coordinated between the 2 aircraft so that they are issued the appropriate advisory. In that sense, each aircraft TCAS II system must identify the other aircraft and establish the link.
 
BTW, I have a different interpretation of the poll. I?d say that the overwhelming number of readers are so indifferent that they can?t be bothered to respond.
This was my interpretation as well. ~110 responses from how many thousand VAF users? Overwhelming majority my Aunt Fanny.
 
The poll isn't the subject of this thread, but since you brought it up, the response rate is consistent with other polls on this forum. If this one is invalid as an indicator, then so are most.

But, like most polls, it's the respondents that provide the data. And in this case, the mandate is clear. It's not even close. If you want to count all the non responders in your camp to make you sleep better, that's fine with me. But the fact is, on other aviation sites I visit, there are people discussing stripping the electrical out of their airplanes to avoid the ADSB requirement or giving up flying altogether. Bottom line- Regardless of what the actual percentages are, there are a lot of your fellow pilots concerned about this issue so you better learn to accept it.

So back to the technical aspects- I'm hearing that 1090 ES was envisioned for the heavy system users and the registration info is a workload reduction for ATC. That's all well and good, but it also sounds like anonymity will work fine if you are VFR and NOT talking to ATC. It certainly can't be any worse than it was last month with mode C targets. And as for Radar trying to differentiate similar targets- I thought the whole purpose of NextGen was to move away from ground based radar? Doesn't an anonymous "VFR" target broadcasting all relevant position, speed and performance data provide all that's needed for collision avoidance? After all, we're not talking IFF here.
 
To ?address? the transponder, it has to have a ?name?. The obvious name is its N number. It won?t work as envisioned without a name.
It would work just as well if, when "anonymous mode" was selected, it generated a random "tail number" like VFR2Q8ZP or VFR868248 or something like that. 978 ADS-B already does this. From an engineering standpoint it should be a fairly easy thing to implement. The challenge is regulatory.

The obvious solution is the simple one. At one time the FAA posted airmen?s social security numbers all over the internet. It took some time, but now most of them are gone. It really shouldn?t be so hard to make the N number database private, for the simple reason that there?s no compelling reason for it to be public.
That's one part of the puzzle, plus
The whole snag became when ATC track data was made available to the general public. Not sure the how or why of that, but it happened.
But more so than that, I want to be anonymous to the FAA when operating VFR outside controlled airspace... just as I used to be when squawking 1200 on a Mode C.


BTW, I have a different interpretation of the poll. I?d say that the overwhelming number of readers are so indifferent that they can?t be bothered to respond.

As Toobuilder notes, response rates to voluntary polls on any topic tend to run only a small fraction of eligible participants anyway. I'd guess that there are plenty of people who would care, if they knew it was an issue.
 
The poll isn't the subject of this thread, but since you brought it up, the response rate is consistent with other polls on this forum. If this one is invalid as an indicator, then so are most.
You are exactly right. Most, probably all, internet polls are worthless.

:cool:
 
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