An ADS-B In Question

Grrr too many typos, so I'll kill my previous posts and correction on Google Groups at least and repost my original here...

On Wednesday, February 10, 2016 at 7:47:03 AM UTC-8, kirk.stant wrote:
On Tuesday, February 9, 2016 at 9:50:02 PM UTC-6, Mike Schumann wrote:

I believe that you are totally misinterpreting the information in the AOPA link you provided. While AOPA has been lobbying for years for the FAA to transmit all TIS-B data so that aircraft without ADS-B OUT will have access to this data, this is NOT what the FAA is doing. Instead, the FAA is actually clamping down and will no longer transmit TIS-B data to aircraft that are equipped with ADS-B OUT equipment that use GPS position sources that do not meet minimal performance standards.

If you want to reliably receive TIS-B data from an ADS-B ground station, your aircraft MUST be ADS-B OUT equipped.

Mike, please go back and carefully re-read the AOPA article. While poorly written, it specifically states that the FAA is implementing 2 changes: First, it will allow aircraft with non-conforming ADS-B out to be seen by certified ADS-B in (which covers people with experimental setups - perhaps even a Powerflarm GPS hooked up to a Trig TT21? Darryl, comment?)

Well yes and no. See below for more. The only change actually happening now will make the glider in your scenario visible to aircraft with certified ADS-B In receivers but it does so only by creating a TIS-B target for your glider, relying on SSR/Transponder positioning and broadcasting that to the client aircraft. So obviously that only works within SSR coverage, and still only broadcasts TIS-B data about that glider if it is within the "hockey puck" of an aircraft with a properly configured complaint ADS-B Out system.

and second, it gets rid of the "hockey puck" limitation on TIS-B traffic transmission, so now anyone with an ADS-B IN receiver will see all the TIS-B traffic around them, not just traffic sent to a nearby certified ADS-B out-equipped aircraft.

No it does not. To be clear what you are talking about is futureware/hopeware and nothing to do with what is actually happening now. See below.


It does talk about "certified ADS-B receivers". Does that include the inexpensive ones used with a tablet or smartphone? I may need to look into that myself.

A certified ADS-B receiver (and display) being talked about by the FAA here is something like say in the low/mid-range GA market like the new Garmin GTX 345 connected to a GTN650 display. If an avionics shop is installing it in the panel of a certified aircraft then it's one of those. Portable ADS-B receivers connected to iPads, tablets, etc. are *not* one of those.

Note: PowerFLARM does not support TIS-B and there has been no information provided by anyone that they are even thinking about adding this functionality to their product. That's a huge shortcoming in the product that is certainly not helping their sales efforts.

Again, PowerFLARM does EXACTLY what it was designed for - provide glider-to-glider (with some additions, like british military aircraft) COLLISION AVOIDANCE information, with the added benefit of seeing all mode S ADS-B and Mode C transponder aircraft nearby. It is optimized for the European environment (no idiotic UAT) but works pretty damn well here in the US.

No argument there.

Now, it looks like adding an inexpensive ADS-B in receiver will get TIS-B into your glider cockpit even if you don't have an ADS-B out setup.

No it won't. Not today. And even if it does in future how you can or cannot connect any of this stuff is a significant issue.

It'll be interesting to see what glider nav setup first incorporates the ability to display TIS-B traffic - I'm hoping SYM on my Oudie will!

Kirk
66

OK more details...

The AOPA article is describing two things. I'll explain it more clearly since I see it is still causing confusion. Those two things a

1. What the FAA is doing now (TIS-B target broadcasts of non-complaint ADS-B out as is documented by the FAA here https://www.faa.gov/nextgen/programs...-15-webV2.pdf). And again, this #1 thing currently happening has nothing to do with getting rid of the need to have complaint ADS-B Out to receive ground based services like TIS-B, it just makes TIS-B traffic data for aircraft with non-complaint ADS-B Out available to those client aircraft that are equipped with certified/compliant ADS-B Out and certified ADS-B In. Previously ADS-B In certified (e.g. panel mount IFR class) systems would not/are not allowed to display those ADS-B targets (yes I kid you not, you cannot make this stuff up). The other part of what is being done here currently is to actually to stop broadcasting TIS-B and ADS-R for non-complaint ADS-B Out client aircraft...which until now the FAA has been doing, so actually that is kind of opposite of that AOPA wants the FAA to do... (in #2 below). That last gotcha will affect more some experimental power aircraft pilots who have been replying on non-complaint ADS-B Out systems to trigger TIS-B and ADS-R client services for their aircraft, maybe even in cases just working when they don't realize why/how and I hope those folks get the message the FAA is in the process of breaking how this works for them. If you know folks doing this in their experimental airplanes, slap them about the head and let them know they may be wanting to install a compliant ADS-B Out system.

and (very differently)...

2. talking about what AOPA wants the FAA to do in future, which is open TIS-B broadcast or something similar. In principle that might mean no client aircraft/hockey puck needed. In practice what it exactly means is... well.... wait and see exactly. The video referred to above is only refers to this second thing AOPA wants the FAA to do.

The FAA is right now rolling out # 1. they are investigating # 2. Actually "working on a plan". So again lets see where that leads and see exactly what they are talking about before worrying too much about the details. It may or may not be technically possible to do exactly what people want with this everywhere.

I suspect neither #1 or #2 FAA action will have little if any affect on USA glider pilots as PowerFLARM does not receive TIS-B. And few gliders have ADS-B Out anything, wether compliant of not, so not much practical increase in observability of those gliders, still maybe useful to know for folks in some areas...

And for the Airliners and many fast jet that rely on TCAS... that all works regardless of what ADS-B anything the glider has, just as long as it has a transponder. Oh and don't rush to add UAT-Out thinking change #1 mean anybody else will see you, the FAA is just using TIS-B here, the FAA ground infrastructure needs the SSR/transponder location to generate that data. Fly around with UAT Out only and no transponder, or outside SSR and ADS-B base station coverage and those certified ADS-B In systems still won't see your glider with a non-compliant ADS-B Out. That well equipped Kind Air or PC-12 who's pilot thinks his certified ADS-B In system can see everything? Bzzzzzt wrong! Down low out in the traffic pattern of a remote airport they'll just run right over the top of a glider with a non-complaint ADS-B Out install without even a beep. (so ideally do a complaint install if you want ADS-B out now, or wait for TABS... *if* TABS regulations happen then that should provide lower cost ways of providing complaint ADS-B Out which will be seen by all 1090ES In equipped aircraft in all situations).

Even if somebody makes a separate ADS-B UAT receiver or box able to merge FLARM and UAT data together it might not deliver a very usable product/significant enhancement over current PowerFLARM systems for most glider pilots. And folks need to be very careful talking about all this home grown/crowd-funded toys maybe eventually doing anything like this. It's one thing to play with stuff, or hope to just display traffic, but it's a very different thing to generate a FLARM like traffic warning. So hands up who would want a box that can display ADS-B traffic on your current soaring flight computer but will not/can not issue any warning at all as you collide with a threat? ... and to be clear to everybody that is exactly what Andy is proposing that crowd funded project actually do. So lets separate our interesting to play with toy ideas from an actually usable collision awareness system like FLARM (or even a modern ADS-B In receiver which does its own style crude and less useful for gliding audible traffic warnings). For the later this seems to me like stuff that I'd want only FLARM doing.

TIS-B location data is derived from SSR/transponder data and so is much less precise than GPS derived FLARM or standard ADS-B. And where that data is generated from a Mode C (vs. Mode S) transponder it is much harder to deduplicate from UAT Out or FLARM (part of the reason that there will be increased ghosting caused by the FAA change #1 on uncertified (e.g. portable) ADS-B in systems). How a FLARM like system would handle that is a research project that likely really needs FLARM R&D like skills, but I doubt it is worth FLARM investing in this for marginal benefit for the small US glider market (doing basic integration with outboard UAT In receivers to enable dual-link receive or adding ADS-R support on the other hand I could see being more useful).

On 2/10/2016 9:53 PM, Darryl Ramm wrote:
So hands up who would want a box that can display ADS-B traffic on your current soaring flight computer but will/can not issue any warning at all as you collide with a threat?

I do, I do...!

Seems to me that simply having a picture of the traffic around you is
sufficient without all the whistles and bells yelling about an imminent
collision. There's another aircraft 5 miles away! Ho hum... Let's see
where he is on the next (or one after) update. Same relative clock
position (azimuth and elevation) only closer? Maybe a threat, I'll
monitor or deviate a little. Yes, in a busy airline cockpit, I can see
the need for collision warnings but, we're flying VFR and are supposed
to be looking outside. Knowing there's an aircraft at a particular
location and closing is all I need or want.

I'm not talking about gaggles or energy lines here. You have Flarm or
PCAS for those situations.

What I'd really like to know is why the FAA doesn't want to transmit all
aircraft positions in the blind. What is to be gained by denying me
information about local (to me) traffic just because I don't have a
particular box in the aircraft? Is it a bandwidth thing?
--
Dan, 5J

On Thursday, February 11, 2016 at 7:55:21 AM UTC-8, Dan Marotta wrote:
On 2/10/2016 9:53 PM, Darryl Ramm
wrote:



So hands up who would want a box that can display ADS-B traffic on your current soaring flight computer but will/can not issue any warning at all as you collide with a threat?



I do, I do...!



Seems to me that simply having a picture of the traffic around you
is sufficient without all the whistles and bells yelling about an
imminent collision.* There's another aircraft 5 miles away!* Ho
hum...* Let's see where he is on the next (or one after) update.*
Same relative clock position (azimuth and elevation) only closer?*
Maybe a threat, I'll monitor or deviate a little.* Yes, in a busy
airline cockpit, I can see the need for collision warnings but,
we're flying VFR and are supposed to be looking outside.* Knowing
there's an aircraft at a particular location and closing is all I
need or want.



I'm not talking about gaggles or energy lines here.* You have Flarm
or PCAS for those situations.



What I'd really like to know is why the FAA doesn't want to transmit
all aircraft positions in the blind.* What is to be gained by
denying me information about local (to me) traffic just because I
don't have a particular box in the aircraft?* Is it a bandwidth
thing?

There are likely bandwidth concerns in some situations. Which is why its important to wait and see exactly what proposal the FAA comes up with. The whole dual-link/claimed need for UAT to free more bandwidth on 1090 MHz has not worked out as the FAA had hoped. And blind transmitting TIS-B would effectively be going to use all that complex FAA ground system that was supposed to help reduce 1090 MHz congestion to actually increase 1090 MHz congestion, oh the irony. I was never strongly convinced by some of the 1090ES bandwidth arguments, there did not seem to be much competitive academic research on this and the European's for example took a different approach that relied on decommissioning Mode C transponders (their interrogation by TCAS especially in crowded airspace wastes lots of 1090MHz bandwidth), change 7.1 to TCAS, and over time maybe other tweaks and improvements to TCAS and SSR systems to reduce transponder interrogation rates and allow more bandwidth at 1090MHz for ADS-B.

But there are likely other reasons than just bandwidth, the FAA also has had some pretty weird approaches to what will "encourage" ADS-B Out adoption. And now everything is such a complex mess that there likely is not a single simple answer to your question. And to some extent as we get closer to 2020 and ADS-B carriage will be mandated in many aircraft TIS-B becomes less interesting (and ADS-B direct and ADS-R (to a much smaller extent because many folks seem to be going 1090ES Out than UAT Out and others dual-link ADS-B In) become more important. And right now where this whole system is at it is important that airspace users in general are encouraged to install ADS-B Out. The primary leading factor is likely to be cost, and while the FAA has not always done things to encourage reduced cost things are finally starting to move better there with mainstream manufactures producing more affordable ADS-B Out systems and hopefully TABS regulations and future availability of TABS devices will help reduce ADS-B Out equipage costs for gliders, that might come with the arguable downside of mandatory TABS/ADS-B Out carriage for gliders. All a part of why waiting and seeing what happens with TABS affects so much here.

The looming 2020 ADS-B carriage mandates (that gliders are currently exempt from) and possible (likely?) changes coming with TABS are all reasons why I'm just not that interested in TIS-B and PowerFLARM integration. But the time anything is here and actually working well enough it will be increasingly irrelevant (as most transponder equipped aircraft equip with ADS-B Out). Dual-link ADS-B receive in a PowerFLARM type systems for non-TIS-B use is probably more interesting longer term, maybe as well for FIS-B/weather and TFR data etc. but who will do all that integration work, and why it would be economically justified for a small USA market is unclear.



--

Dan, 5J

snip

On 2/11/2016 10:00 AM, Darryl Ramm wrote:
the FAA also has had some pretty weird approaches

Yaaas... When I was working on ASDE-X in the mid-2000s, the FAA
required us all to fly to Washington, DC simply to have our pictures
taken for our "Public Trust" badges (at tax payer expense, of course).
Eventually someone at FAA realized that we slimy contractors had cameras
of our own to make our own company badges and we could simply email the
pictures to them to make their badges for us.

So glad to be retired... :-D
--
Dan, 5J

On Wednesday, February 10, 2016 at 11:25:05 PM UTC-6, Darryl Ramm wrote:

(Lots of good stuff clipped...)

Well darn, I need to brush up on my reading comprehension skills! I felt that the AOPA article was poorly written (and mentioned it) but I guess I (and some others) read what we wanted to read...

Darryl, thanks again for stepping in and setting us straight - my head hurts just thinking about all this stuff!

Cheers,

Kirk
66

Even if somebody makes a separate ADS-B UAT receiver or box able to merge FLARM and UAT data together it might not deliver a very usable product/significant enhancement over current PowerFLARM systems for most glider pilots.. And folks need to be very careful talking about all this home grown/crowd-funded toys maybe eventually doing anything like this. It's one thing to play with stuff, or hope to just display traffic, but it's a very different thing to generate a FLARM like traffic warning. So hands up who would want a box that can display ADS-B traffic on your current soaring flight computer but will not/can not issue any warning at all as you collide with a threat? ... and to be clear to everybody that is exactly what Andy is proposing that crowd funded project actually do. So lets separate our interesting to play with toy ideas from an actually usable collision awareness system like FLARM (or even a modern ADS-B In receiver which does its own style crude and less useful for gliding audible traffic warnings). For the later this seems to me like stuff that I'd want only FLARM doing.

________________

These are all important statements. People need to take care with projects of this type and in general collision warning is best left to professional developers with the specialized skills to deal with all the complexities. Caveat Emptor.

However...To the extent that any GA in the US equip with UAT Out it would be nice to have a way for glider pilots to see them that is better than PCAS - which from my perspective becomes nearly useless as gliders equip with and use transponders - the nuisance alarms just become intolerable if you fly close to one or more of them. Ask me why I know this.

Since UAT Out is most likely to be carried in GA aircraft rather than gliders lacking Flarm, a simple traffic alert at 1mi and +/- 1000' ought to be sufficient - and certainly better than invisibility. While it would be nice in a perfect world, I don't anticipate GA traffic needing sophisticated Flarm collision algorithms unless someone in a Mooney wants to come thermal with us. Such a simple traffic warning appears to be possible and ought to be better than nothing. All the other stuff is either transitional (TIS-B), or a future option (FIS-B - assuming a glide computer maker decides they want to take up the development just for the US - which is a big unknown at best).

All of this is further support that gliders should equip with Flarm and a transponder first and UAT Out never. If you go ADS-B Out absolutely make it 1090ES or you will never get Flarm collision warning capability - at least not unless Flarm decides to add it to their box.

9B