The ‘other’ ADS-B

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Lou
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Re: The ‘other’ ADS-B

Post by Lou »

Rich I think you are correct - for our aircraft it will likely not matter practically. I guess 'diversity' gives optionality, when one agency or another prescribes what kind of antenna you require. I don't know of any antenna requirement in the FAA mandate, and who knows what, if any, mandate will be prescribed for GA in Canada.
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Re: The ‘other’ ADS-B

Post by Lou »

My avionics guy tells me that among the suite of new Garmin product announcements yesterday is the GTX345D, the anticipated diversity capable "low-cost" ADS-B transponder. I have not studied the full list of features yet,although I did note that it is available in the Remote configuration. A real bargain at only 7 AMUs!
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Re: The ‘other’ ADS-B

Post by Rich »

Lou wrote: Tue Mar 26, 2019 4:04 pm My avionics guy tells me that among the suite of new Garmin product announcements yesterday is the GTX345D, the anticipated diversity capable "low-cost" ADS-B transponder. I have not studied the full list of features yet,although I did note that it is available in the Remote configuration. A real bargain at only 7 AMUs!
I sat in on this morning's seminar by Garmin and they tossed that out at the last of the meeting, so that would be a viable additional option.
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Re: The ‘other’ ADS-B

Post by CFIDave »

My guess is that Garmin just announced "D" (diversity antenna) versions of the GTX335(R) and GTX345(R) so that they would have products should the Canadians (NavCanada) require diversity ADS-B Out antennas. These are apparently needed so that Aireon satellites can track aircraft using ADS-B. Canada is unlikely to create a network of ADS-B ground stations similar to those deployed in the US, so NavCanada expects to be dependent on satellite ADS-B.

A Canadian requirement for diversity antennas has been proposed, but is being opposed by groups like AOPA, since it might preclude US N-registered aircraft (with only single-antenna ADS-B 1090ES transponders) from flying in some Canadian airspace.
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Re: The ‘other’ ADS-B

Post by Rich »

The Aireon system is being promoted as a world-wide solution, if only to satisfy the needs of ATC. Canada is an example where it's highly impractical to build out a network of ground stations. Oceanic travel is the other obvious use case.

Diversity might not be needed in our little plastic airplanes. But I do know of a guy who failed his ADS-B reimbursement test twice. He attributes this to doing lots of maneuvering while on the flight (above 10,000 ft.). His third flight he took pains to cut this way down and he did pass. I don't recall what airplane type and whether he was 1090ES or 978UAT though it's likely it was an aluminum plane. On the other hand I've done post-flight evaluation of my system several time with just the bottom-mounted transponder antenna and have fully passed all the tests every time. I've never inhibited maneuvering on these flights, often deciding post-flight to see what the validation report looked like.
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Re: The ‘other’ ADS-B

Post by Lou »

In Canada radar surveillance is the exception not the rule. The way I see it the opportunity to be followed by ATC in every corner of the country is appealing from a safety point of view. If you have ever flown north of the tree line you know what I mean. There is nothing but wilderness. I guess diversity makes sense in that if you are going to spend a pile on a new transponder, you may as well spend a little more to make sure it works everywhere you would like to go. If you should ever go down, ATC can say we lost him *there*. That's worth as much as an ELT that probably won't work anyway.

Is this logic correct, or am I missing something?
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Re: The ‘other’ ADS-B

Post by Pascal »

Lou wrote: Wed Mar 27, 2019 3:57 am Is this logic correct, or am I missing something?
Lou your logic is correct. One data point is that in Canada the General Aviation fleet is old. Planes are 50 years old on average I believe. At my airport, I'm one of the few pilots younger than 50 years old. That worries me. Will the local COPA chapter (Canadian AOPA) survive once its old members retire?

In my part of the country, province of Quebec, most airplanes are old rusty 172s or similar. In my pilot's association, I have learned to my absolute dismay that more than a third of pilots have not even filed a flight plan over the last ten years. Most of them still use paper charts, and forget about standard pattern entry.

Let's say a pilot is in his seventies, has had his airplane for twenty years, and the engine is edging towards TBO. They have a Loran, an ADF and old Narco radios. It's going to be a hard pill to swallow to cough 8000$ cad (6000$ usd) for rinky dinky old plane for someone who knows he will have to sell it within 5-10 years maximum when he loses his medical or runs out of money for retirement.

I guess I just wish that after the 2020 deadline in the U.S. prices for equipping ADSB-OUT will go down significantly.
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Re: The ‘other’ ADS-B

Post by TimS »

Lou wrote: Fri Jan 25, 2019 7:40 pm I learned something this week that might be useful on this topic. Some transponders have "diversity" meaning that they use two antennas, top and bottom. The GTX 345R does not have diversity, but this person was speculating that the next generation of Garmin transponders might have it, in which case a one size fits all ADS-B solution will be available for C registrations. More cost for the antennas, sure, but compliant in all environments.

I am in the Edmonton FIR, which is the first FIR to go live with Aireon. I pick up ADS-B targets on my Stratux inside the CYEG control zone. I am curious to see what I get once the whole region goes live.
Last I looked, Garmin had the 335D and 345D diversity transponders. No remote mount versions of them at the time.
I highly doubt diversity would affect signal reception in a Diamond. Not only is the plan small enough to case a really tiny shadow, the body is fiberglass which allows the radar/transponder pulses to go through.

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Re: The ‘other’ ADS-B

Post by Charles »

The latest announcement from NavCanada confirms the schedule and requirements: ADB-B Out on 1090ES is required in 2023 for Class A airspace, 2024 for Class B (which in Canada is the airspace between 12500 and FL180), and 2026 or later for class C and D.

The requirement for diversity remains vague: "Have antenna capability for broadcast toward space-based ADS-B receivers emitting 1090 MHz extended squitter. This requirement can be met either through antenna diversity (the use of a top and bottom antenna) or with a single antenna that is capable of transmitting both towards the ground and up towards satellites."

I asked Diamond some time ago whether a bottom-mounted antenna would be good enough given the composite fuselage and the answer I got at the time was "this is still a long ways off so don't worry about it". Well, not anymore. Does anybody know what would be acceptable? Could we just bring the bottom-mounted antenna inside the tail and turning it on its side :roll:

https://www.navcanada.ca/en/flight-plan ... onal-.aspx

I work for a satellite company and I've asked our RF experts about this. Will report back.
Last edited by Charles on Wed Mar 22, 2023 9:56 pm, edited 1 time in total.
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Re: The ‘other’ ADS-B

Post by Charles »

For the record, this was the response from the Director of Airworthiness at Diamond in 2021:

While it is true that Nav Canada has opted for a space based system for ADS-B services it is not yet mandated by TCCA nor is the plan in place for a date to implement this mandate. Nav Canada is a private corporation and cannot mandate such things. We are working with TCCA to stay on top of the requirements and will be testing the current configuration to see if it meets the needs of the space based system without the extra antenna.

There has been initial testing completed and the lower antenna can be seen by the Aireon system ( on a metal aircraft) but the refresh rate is not good enough. It can drop off for more than 10 seconds. It is possible that for fabric and composite airplanes we could find a position on the airplane that will be suitable to meet the requirements.

Thank you for your positive comments. Feel free to contact us if you have any questions.
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