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ADSB dual diversity

Weefle

Well Known Member
Just wondering what other builders are doing in Canada to anticipate the new regs that NAV Canada is supposed to be coming out with one of these days for ADSB in/out.
Seems like the only option now is the UVionox tailbeacon.
Should a person just wait then go back and rewire when this gets settled?
I’m perplexed as to what to do.

Thanks
K
 
First off... NavCanada doesn't make the regulations. They may *want* us to have diversity, but they have to show it's necessary.

It's been shown that a belly-mounted antenna on a jumbo jet works for the Aireon network. We may never be mandated to have diversity antennas on our little four-bangers.

All that said, the TailBeaconX is a simple way to meet a diversity requirement.
 
It's been an interesting saga with NavCanada building the satellite network, but having no authority to regulate it's use. Hopefully it doesn't turn into a gigantic waste. Transponder airspace exists in the regs and is fairly common. ADS-B is different, so NavCanada can't make "ADS-B airspace". That's up to Transport Canada.

NavCanada has also been selling this to their customers as a way to provide more efficient and safer routings in areas with no RADAR coverage. Think sparsely settled areas, the arctic and oceanic airspace. Even lower altitudes farther from a RADAR site has no coverage. Pre-COVID, there didn't seem to be much motivation to staff the appropriate ATC centers to utilize this capacity. Now they're laying off controllers and there's certantly no hope to take advantage of greater surveillance capabilities with ADS-B. How can they possibly provide greater surveillance and ATC control with fewer ATC controllers?

I can certantly see and appreciate the benefits of ADS-B. I wish they would just hurry up and figure this mess all out so we can make decisions on our planes. With no real direction from TC or NavCanada, the avionics suppliers aren't in any great hurry to develop equipment that has a stagnant market with no direction. The whole thing has really been botched, and they're fixing it at the speed of government!
 
My remote Garmin GTX 45R has both frequencies of ADS-B on a belly mounted standard transponder antenna. This meets the current requirements for US ADS-B. For future diversity I installed and prewired a RAMI AV-11 rod type antenna under the fiberglass fairing at the top of my VS. Unfortunately, if diversity is ever required in Canada, I'll have to change out my remote transponder for a much more expensive one :(. But at least I can connect to the prewired top mounted antenna without any trouble.

Now if they would only make up their minds/reconsider the 406 ELT requirements:eek:
 
My remote Garmin GTX 45R has both frequencies of ADS-B on a belly mounted standard transponder antenna. This meets the current requirements for US ADS-B. For future diversity I installed and prewired a RAMI AV-11 rod type antenna under the fiberglass fairing at the top of my VS. Unfortunately, if diversity is ever required in Canada, I'll have to change out my remote transponder for a much more expensive one :(. But at least I can connect to the prewired top mounted antenna without any trouble.

Now if they would only make up their minds/reconsider the 406 ELT requirements:eek:

So if one was to install one antenna like this on the belly and one on the top of the VS this should at least cover the antenna portion of the equation?

Keith
 
I have gone with a full IFR panel and decided to wait on trying to meet potential Canadian requirements. I think it will be a while before it is decided and even longer phase in period. If and when it gets implemented it likely will not be required in the airspace I regularly fly in. Between now and then a lot of options will be developed to meet the requirements and equipment prices will likely fall.
Look how long it took to implement the 406 ELT requirement. Was talked about for years.
 
It's been an interesting saga with NavCanada building the satellite network, but having no authority to regulate it's use. Hopefully it doesn't turn into a gigantic waste. Transponder airspace exists in the regs and is fairly common. ADS-B is different, so NavCanada can't make "ADS-B airspace". That's up to Transport Canada.
ADS-B is just the system that receives the transponder signal. Your aircraft still uses the same frequencies transponders always used, with more data attached to the signal. NavCanada built the satellite network, and the only country *not* committed to space-based ADS-B is... The US.

Jetmart said:
Look how long it took to implement the 406 ELT requirement. Was talked about for years.
Long enough that it's been superseded by a number of better options, and yet they still force it down our throats.
 
A few good comments have already been made here. I'll see if I can provide a little bit of a summary.
1) there is no ADSB mandate in Canada
2) while Nav Canada wants ADSB mandated, the Minister of Transport finally woke up and put Nav Canada back in its place as Transport Canada regulates airspace
3)with 2) above in mind, Nav Canada is doing everything in its power to manufacture data in support of forcing Transport Canada into an ADSB mandate
4) what that mandate will look like is unknown - Nav Canada wants it to be a full diversity mandate and doesn't give a flying fig about what compliance costs us little guys because we're just an irritation to Nav Canada
5) there are more ways than just a full-blown diversity transponder to squirt some signal upwards toward satellites - in speaking with the director of product engineering for one avionics manufacturer he clearly stated they will have a product to meet the Canadian mandate once that mandate is released. He also clearly stated that much lower-cost methods of compliance would be high on their list of products to offer to their customers. In short, he felt Nav Canada was seriously over-stating the requirement as well as over-reaching their authority. I tend to agree with him on both points.
6) be aware that Nav Canada has a huge investment in Aerion and will go to great lengths to see it mandated for use in Canada - that includes making up data to suit their desires while excluding data which might support something less than full diversity transponders.
7) get on your local representative (MP) to ensure they are aware this is happening and to keep pressure on the Minister of Transport to consider the impact of compliance for we non-airline customers of Nav Canada.

I strongly believe that Nav Canada has become "Airline Canada". I just as strongly believe that Canadian airspace belongs to all Canadians, not just to the airlines. Nav Canada needs its chain given a good hard yank by Canadian taxpayers.
 
So if one was to install one antenna like this on the belly and one on the top of the VS this should at least cover the antenna portion of the equation?

Keith

Yes. From reading the installation manual for my Garmin GTX 45R and discussing the possible diversity requirement for Canadian ADS-B with my avionics supplier, this is my understanding. For diversity, you need a bottom and top mounted antenna. The signals from the diversity XPDR alternate between the two antennas.

I did this now because it was so much easier than after the plane was built. Having said that, even though the VS is not yet mounted to the airplane, it was not exactly "easy". I had to de-rivet the bottom ribs and get creative to install an adel clip to secure the RG-400 cable to the VS spar. Then install a bulkhead BNC fitting to the bottom rib and re-rivet.
 
Awesome...thanks for all the responses. I am sure we have not heard the last of this discussion.

Cheers

Keith
 
I follow the Aireon development with quite some professional interest...

So far, I get the feeling that some companies are literally gambling "Vegas style", big time. Can't blame them (unless it's all taxpayer money), satellite based definitely has potential. Especially for oceanic airspace and it may for the first time allow some kind of surveillance data competition in a certain block of airspace (without having to own ground based surveillance assets). Who wouldn't want to be among the early movers and on a "sexy" project?!

But there are also serious doubts and concerns, of course...
General Aviation must be extremely careful and lobby in order not to become a playing ball in a really large scale experiment of specific commercial interests...

First, it looks like the whole thing was a "late in the game" trick idea by/with iridium to sell/fill some spare satellite capacity with a novel application. Before any ops concepts were written, separation standards evaluated etc... A classic money/engineering driven approach that is prone to hit problems if not approached from the operations angle at the same time...
They were practically launching satellites before anything was sorted out or even studied beyond high level concepts. With the hope[sic!] that it would eventually work out and perform. Ironically, launched by [awesome!] SpaceX, which ultimately may anyway have the better platform/solution for such an ops concept with their starlink constellation... ;-) [I wouldn't be surprised if we'll eventually mount next gen starlink digital transponders & radios on our airplanes...]
Not only could that cover the surveillance part but more importantly the communications part as well! Multiple times more redundant and with less latency. But they have bigger fish to fry right now, I guess...

Aside from transatlantic traffic, I have yet to see proof that Aireon can reliably track all targets in a dense continental airspace, including all low flying piper cubs etc... Hence the push in Canada for diversity (lots of "vegas money" coming from there). If you only have a partial surveillance picture, you have a useless picture, at least in the sense of ATC.
Anyone else noticed the gradual shift of their offerings on their website more into the direction of business analytics / flow management and such? ;-) Drifting away from the surveillance angle which was dead center in the beginning...

Another big problem is the business case. Unless you can massively reduce minimum separation and as a result move lots more traffic (assuming demand comes back the same or better post-covid!) and/or replace radar/WAM ground based surveillance infrastructure, the whole thing isn't much more than a "me too" affair...
The infrastructure gamble, by the way is somewhat a shared problem with the U.S. ADS-B approach, just finding out now that turning off radars is not going to happen as quickly as imagined...)

In order to reduce minimum separation you have to convince a lot of bright mathematicians at ICAO level which are really good at collision risk modelling. Problem there is, surveillance is only one part of the equation. And through lots of gradual improvements (0.5 degree lateral tracks, ADS-C longitudinal etc...), the position uncertainty has already been reduced quite a bit, so the improvements possible through Aireon aren't as crass of a magnitude as it may initially seem like. But better it may be.

Then, the biggest problem is RCP (required communication performance). Knowing where flights are is only half the game. You have to be able to make something out of it, and do so reliably. Called controller and communication intervention buffer. And for that, from what I've gotten to read so far, the Aireon concept appears to be pretty much nil, as a result the big bets on improvements appear to be more hope than reality so far...

I would really slow-roll the diversity topic or else make them pay for it!
It's their business, not ours...

I believe in WAM and radars anyway. And for that, our simple basic mode-s transponders are going be sufficient for quite some time!
 
What an interesting discussion...
Keep in mind that Nav Canada has responsibility for the surveillance of the skies in Canada for the purposes of ATC. They badly want to decommission ground-based radar stations because, in our harsh environment, those stations cost a fortune to maintain.

As you've pointed out, the Vegas-style gamble was made in hopes that Nav Canada could throw their weight around and convince Transport Canada to mandate the use of their Aerion product so there would be a guaranteed domestic customer base. Thankfully Transport Canada woke up before it was too late. Still, Transport Canada has for many years performed as Nav Canada's patsy so we'll see if the regulator will actually add any value for Canadians. Given the current Minister of Transport I'm not holding my breath.
 
NavCanada maintains RADAR sites (and radio stations; PAL, RCO) in some pretty remote locations. I'm sure there's significant motivation ($$) to shut those down. There's also significant collision risk in non-RADAR areas (not $$ though). Space based ADS-B has the potential to solve that problem, if only they'd have the controllers available to do so. At work, it's sometimes a bloody nightmare to get a clearance into non-RADAR controlled airspace when the controller is so over worked. So that just leaves me waiting in the equally congested uncontrolled airspace.

I suppose the point of my rant is for NavCanada/TC to hurry up and figure out what they want to do, what equipment we need and make sure compliance isn't too expensive. I'm not just being cheap either. If compliance is too expensive, people won't buy the equipment. Instead they will fly around skirting the airspace and moving the congestion away from where NavCanada has the ability to mitigate the collision risk. That also drives away NavCanada customers (which again is $$).

As for what I'm doing, fortunately I'm early on in the fuselage. I'm hoping that by the time I need avionics, this mess has been cleaned up and there's several reasonably priced options available from the avionics suppliers.

It's also not just us that's frustrated. The ADS-B package for a Dash-8 is about half the price of an RV-8.
 
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Nav Canada needs its chain given a good hard yank by Canadian taxpayers.

NavCanada has had it's chain yanked rather hard by COVID. They're hemorrhaging money and trying to lower costs and increase revenues any way they can. Wait for this year's NavCanada bill, I think we'll be in for a surprise.
 
Diversity antenna

As I understand the requirement, the ADSB signal should be able to propagate
from the aircraft towards the grund and the sky at the same time.
This can be done with two antennas on a metal airplane, one on the top and one on the belly, therefore the diversity requirement.
But if you have a plastic wingtip I think that it would work with one antenna without a ground plane, a dipole. Any reason this would not work?

https://www.aircraftspruce.com/catalog/avpages/antennasystems1.php
 
But if you have a plastic wingtip I think that it would work with one antenna without a ground plane, a dipole. Any reason this would not work?

From the Aircraft Spruce FAQ for this product:

Q. Can I use it in the plastic or fiberglass wingtip of a metal airplane ?
A. Yes, but the antenna must be as far from the metal wing as possible. We have had limited success with this. Not recommended for the RV series aircraft.
 
From the Aircraft Spruce FAQ for this product:

Q. Can I use it in the plastic or fiberglass wingtip of a metal airplane ?
A. Yes, but the antenna must be as far from the metal wing as possible. We have had limited success with this. Not recommended for the RV series aircraft.

I think it's fair to say that the limited success is at least partially due to the limited testing they've done, as it's not the recommended mounting location.
 
From the Aircraft Spruce FAQ for this product:

Q. Can I use it in the plastic or fiberglass wingtip of a metal airplane ?
A. Yes, but the antenna must be as far from the metal wing as possible. We have had limited success with this. Not recommended for the RV series aircraft.

Do a search on threads having to do with the uAvionix TailbeaconX. It essentially is a transponder with just such a dipole antenna. Threads on this forum confirm that wingtip installations DO work.

I am aware of one such installation in an RV based at our airport. That aircraft builder/owner is a participant in the uAvionix flight trials. He is bound by NDA to not discuss details so I'm sure he is not able to join the discussion here. I'm not speaking on his behalf, merely confirming that his installation in the wingtip has, so far, proven successful with both ground-based Secondary Surveillance Radar (traditional 1090 transponder operation) as well as Aireon.
 
That aircraft builder/owner is a participant in the uAvionix flight trials. He is bound by NDA to not discuss details so I'm sure he is not able to join the discussion here.

I'm fairly certain that the NDA was intended to keep the product under wraps until it went public. Now that it's available, i'm sure uAvionix would appreciate any info that helps sell units being made public. I was a beta tester as well.
 
You make a good point, Rob. Since I'm not party to the details of the NDA I was merely assuming it covered discussion of performance of the TailbeaconX vis a vis Aireon monitoring.
 
You make a good point, Rob. Since I'm not party to the details of the NDA I was merely assuming it covered discussion of performance of the TailbeaconX vis a vis Aireon monitoring.
They probably wouldn't want anyone sharing specifics, like actual power output, signal strength received, etc. etc. But we as testers never got to see any of that data anyway.

The "big picture" result was that (as far as they told the testers) everyone with a functional TBX was picked up perfectly by the Aireon satellites on every flight.

The only issue i've had with mine is that on my last flight the tower never picked me up on departure. I was leading a formation flight, so I had to have my wingman turn his on, and I turned mine off rather than try to diagnose. On return to the airport an hour later, I heard multiple people having issues with the tower picking them up, so i'm still not 100% sure that it was me having the issue. I haven't flown again since that flight so I haven't been able to confirm. It could also be that we got up and moving before the GPS locked in. The TBX won't broadcast a ModeS signal without a lock.
 
Perhaps while we are discussing what’s coming down the pipe what are some thoughts on VOR. Seems like we’re seeing less VOR use and more GPS. Is it worth considering a VOR/ILS/GS antennae at this time? Is the ILS system going to be phased out eventually and go total GNSS?

I’m planning for a full legal IFR panel so could someone school me in what I should put in the panel? I would need to buy the avionics about 12-18 months from now. Do I wait to see what happens in that situation?

Thanks

Keith
 
Perhaps while we are discussing what’s coming down the pipe what are some thoughts on VOR. Seems like we’re seeing less VOR use and more GPS. Is it worth considering a VOR/ILS/GS antennae at this time? Is the ILS system going to be phased out eventually and go total GNSS?

I’m planning for a full legal IFR panel so could someone school me in what I should put in the panel? I would need to buy the avionics about 12-18 months from now. Do I wait to see what happens in that situation?

Thanks

Keith

In Canada you require 2 independent Nav's sources so a single GTN like the 650 will not meet the requirements. Instead of putting a 2nd Nav/COM which would have traditionally been done in the past I went with a 2nd GPS/COM - GTN 650 and GNC 355 GPS/com.
 
If one spends a little while reading NavCanada's future navigation planning documents it becomes clear that VORs are not going totally away but a lot of them are disappearing.

As Glenn mentioned, we are required to have more nav redundancy than our cousins to the south. In my risk assessment I decided I wanted to have the backup of a second ILS receiver. Now that options for GPS navigators have expanded I'm not sure I would have made that same decision. Still, GPS doesn't work all the time so I'm not feeling too bad about having a GPS navigator backed up by VOR-ILS capability in a second box.
 
In Canada you require 2 independent Nav's sources so a single GTN like the 650 will not meet the requirements. Instead of putting a 2nd Nav/COM which would have traditionally been done in the past I went with a 2nd GPS/COM - GTN 650 and GNC 355 GPS/com.

That sounds like a very logical way to go. Can do any approach except NDB, and those are exceedingly rare. After a nav source failure, there's still a significant number of options available with at least a WAAS GPS and COM left functioning.

If a big solar flare takes out the GPS constellation, there's the ILS/LOC/VOR capability in the GTN to fly an approach somewhere. That's the NavCanada "recovery network".
 
Perhaps while we are discussing what’s coming down the pipe what are some thoughts on VOR. Seems like we’re seeing less VOR use and more GPS. Is it worth considering a VOR/ILS/GS antennae at this time? Is the ILS system going to be phased out eventually and go total GNSS?

VOR: going to reduce to an absolute minimum-minimum coverage in practically all countries, but not completely disappear for now.

DME: a lot of VOR's are replaced by simply DME's (instead of completely removed), which allows airline FMS to do a very good backup to GNSS/GPS.
DME/DME triangulation however I haven't seen in the small plane arena, not even as a backup. in most other DME applications, GNSS is usually accepted as a full replacement (e.g. ILS approach distance information). So DME can be skipped for small planes IMHO.

NDB/ADF: will be (or is already mostly) gone sooner than later. not worth investing in.

ILS: will be here to stay for a looong time, at least on the major airports, despite what some in the industry would like to see. GBAS is a failure in my opinion and there is talk about CAT III GBAS for what? like 20 years almost! and still not a fact... also, talking to GBAS-knowledgeable people, while it mostly works for most of the locations in the world, it's almost impossible to remove the final uncertainties regarding atmospheric distortions and universal application for all parts of the world (canada and mainly alaska apparently being some of the nail-biters).
The business case and equippage rate are however directly tied to GBAS being CAT II/III capable and this in all parts of the world. As long as that does not happen, there will be many ILS's around.
And the moment you anyway need an ILS receiver, there is little to no incentive to equip with GBAS as the existing SBAS CAT I RNP approach capability (which any modern certified Garmin etc... will do) will be good enough for a long while. So a definite yes on the ILS! and GBAS/GLS is DOA.

regards
 
Diversity antenna

So now we send 1090 out for others to see us,and today our little antenna is belly mounted, why not mount on to instead
I would assume ATC would receive the neccary info back from the satellite

Seems like a simple solution.
 
So now we send 1090 out for others to see us,and today our little antenna is belly mounted, why not mount on to instead
I would assume ATC would receive the neccary info back from the satellite
In the vicinity of an airport, ATC will receive your transponder signal from a top-mounted antenna easily, except for specific angles at which the bulk of your airplane just happens to be exactly between your antenna and theirs. The same is true for a bottom-mounted antenna talking to a satellite that's exactly on the opposite side of the airplane. Hence the requirement for diversity, to be doubly sure that there are no dead spots.

Nobody seems to be considering that there are multiple satellites and not all of the ones in range will be directly overhead your airplane. An off-angle satellite will pick up a bottom-mounted antenna.
 
I have a bottom-mounted antenna and have confirmation that Aireon has "seen" and tracked my aircraft fairly reliably. It helps that it's a composite aircraft but it still has a ground plane which should limit upward radiation of the signal. This is one of the reasons I believe Nav Canada's suggestion that Diversity is the ONLY way to get ADSB compliance in Canada is evidence of their desire to use a very large stick to swat a very small bug.
 
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