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Thank you for the explanation, Darryl. I appreciate the time you put into your commentary.

Thanks!
Just trying to keep up with the development of systems and processes, and not be last in line in 2019 at the avionics shop.
BillT

Darryl,

Question regarding your statement that gliders are largely exempt from needing ADS-B Out to fly in 2020 inside some airspace which requires ADS-B Out.

I'm based inside a Mode C Veil. My glider has a TT21 equipped with the latest firmware 2.4 and 1.10 (I also have a PowerFlarm core providing ADS-B In).. Come 2020, since I have a Mode S transponder, I think I'll be required to install a C145a GPS that is known to work properly with my TT21.

Do you agree?

-John, Q3

On Thursday, March 26, 2015 at 6:46:08 AM UTC-4, Darryl Ramm wrote:
--snip--
It has always been the case that in an experiential aircraft can install a non-TSO (and non-meets performance of...) GPS source for ADS-B Out as long as all the basic things are done right and the aircraft correctly transmits the appropriate SIL parameters to advertise it is using a non-complaint GPS source. However that will *not* meet the 2020 carriage mandate, and allow that aircraft to fly in airspace requiring ADS-B Out (again which glider are largely exempt from).
--snip--

John, I'm sure Darryl will be along shortly.
Gliders are not required to have a transponder or ADS-B Out.
You are not required to add Out GPS data to the Trig unless you chose to. But if you do it must meet the standards.
FAA has recently reworded the language that allows "Experimental" kit built aircraft to install non TSO'd ADSB out systems as long as they meet the same standards. I'm not sure if that applies to experimental gliders.

We have Trig21 on some of our gliders, inside the Mode C Veil, we are not planning to add GPS to the Trig.
BillT

On Thursday, April 2, 2015 at 5:42:12 PM UTC-7, Bill T wrote:
John, I'm sure Darryl will be along shortly.
Gliders are not required to have a transponder or ADS-B Out.
You are not required to add Out GPS data to the Trig unless you chose to. But if you do it must meet the standards.
FAA has recently reworded the language that allows "Experimental" kit built aircraft to install non TSO'd ADSB out systems as long as they meet the same standards. I'm not sure if that applies to experimental gliders.

We have Trig21 on some of our gliders, inside the Mode C Veil, we are not planning to add GPS to the Trig.
BillT

Bill is right. You won't need to do this, not unless the regulations are changed, and that would be a huge surprise.

You need to read 14 CFR 91.225.

Because of the the glider/electrical system exemption you can fly within a Mode C Veil after 2020 without ADS-B Out. Obviously when that close to lots of traffic I'd hope glider owners do equip their aircraft with a transponder, as you have--thanks! And that transponder provides lots of protection, importantly it makes you visible to the TCAS systems in just about all airliners and fast jets.

If you chose to install ADS-B Out and your glider is certified then you must meet all the requirements of the 2020 ADS-B Out Mandate, that unfortunately is not something that a Trig TT-21 transponder can do, you need to have a TT-22 because of FAA's silly power requirements for ADS-B Out. And yes you would also likely need a TSO-C145a (or later) GPS source. If your glider is experimental then you have cheaper options (but you need to be careful that say if you connect a commodity GPS to the Trig it won't give you any post 2020 mandate privilege e.g. not allow your glider to enter class B or C airspace... probably not an issue :-)).

BillT, Darryl, thanks for your replies. I really got confused with 14 CFR 91.215 and 91.225! I reread them again, and now I see where I went wrong.

It's nice that I won't have to spring for an expensive C145a GPS source. My glider is experimental so I do have the option to feed it with the PowerFlarm GPS. I won't ever be going into Class B or C airspace, though, so I'm not sure what I'd gain by implementing ADS-B Out via this option.

A question regarding TCAS - it calculates target range using reply timing rather than received power level, doesn't it? In other words, TCAS doesn't work like the PowerFlarm or Zaon PCAS, so I don't have to worry about getting too close to airliners because I have a 130W instead of a 250W transponder.

-John, Q3

On Thursday, April 2, 2015 at 9:36:07 PM UTC-4, Darryl Ramm wrote:
On Thursday, April 2, 2015 at 5:42:12 PM UTC-7, Bill T wrote:
John, I'm sure Darryl will be along shortly.
Gliders are not required to have a transponder or ADS-B Out.
You are not required to add Out GPS data to the Trig unless you chose to. But if you do it must meet the standards.
FAA has recently reworded the language that allows "Experimental" kit built aircraft to install non TSO'd ADSB out systems as long as they meet the same standards. I'm not sure if that applies to experimental gliders.

We have Trig21 on some of our gliders, inside the Mode C Veil, we are not planning to add GPS to the Trig.
BillT

Bill is right. You won't need to do this, not unless the regulations are changed, and that would be a huge surprise.

You need to read 14 CFR 91.225.

Because of the the glider/electrical system exemption you can fly within a Mode C Veil after 2020 without ADS-B Out. Obviously when that close to lots of traffic I'd hope glider owners do equip their aircraft with a transponder, as you have--thanks! And that transponder provides lots of protection, importantly it makes you visible to the TCAS systems in just about all airliners and fast jets.

If you chose to install ADS-B Out and your glider is certified then you must meet all the requirements of the 2020 ADS-B Out Mandate, that unfortunately is not something that a Trig TT-21 transponder can do, you need to have a TT-22 because of FAA's silly power requirements for ADS-B Out. And yes you would also likely need a TSO-C145a (or later) GPS source. If your glider is experimental then you have cheaper options (but you need to be careful that say if you connect a commodity GPS to the Trig it won't give you any post 2020 mandate privilege e.g. not allow your glider to enter class B or C airspace... probably not an issue :-)).

On Friday, April 3, 2015 at 7:23:35 AM UTC-7, John Carlyle wrote:
BillT, Darryl, thanks for your replies. I really got confused with 14 CFR 91.215 and 91.225! I reread them again, and now I see where I went wrong.

It's nice that I won't have to spring for an expensive C145a GPS source. My glider is experimental so I do have the option to feed it with the PowerFlarm GPS. I won't ever be going into Class B or C airspace, though, so I'm not sure what I'd gain by implementing ADS-B Out via this option.

A question regarding TCAS - it calculates target range using reply timing rather than received power level, doesn't it? In other words, TCAS doesn't work like the PowerFlarm or Zaon PCAS, so I don't have to worry about getting too close to airliners because I have a 130W instead of a 250W transponder.

-John, Q3

On Thursday, April 2, 2015 at 9:36:07 PM UTC-4, Darryl Ramm wrote:
On Thursday, April 2, 2015 at 5:42:12 PM UTC-7, Bill T wrote:
John, I'm sure Darryl will be along shortly.
Gliders are not required to have a transponder or ADS-B Out.
You are not required to add Out GPS data to the Trig unless you chose to. But if you do it must meet the standards.
FAA has recently reworded the language that allows "Experimental" kit built aircraft to install non TSO'd ADSB out systems as long as they meet the same standards. I'm not sure if that applies to experimental gliders.

We have Trig21 on some of our gliders, inside the Mode C Veil, we are not planning to add GPS to the Trig.
BillT

Bill is right. You won't need to do this, not unless the regulations are changed, and that would be a huge surprise.

You need to read 14 CFR 91.225.

Because of the the glider/electrical system exemption you can fly within a Mode C Veil after 2020 without ADS-B Out. Obviously when that close to lots of traffic I'd hope glider owners do equip their aircraft with a transponder, as you have--thanks! And that transponder provides lots of protection, importantly it makes you visible to the TCAS systems in just about all airliners and fast jets.

If you chose to install ADS-B Out and your glider is certified then you must meet all the requirements of the 2020 ADS-B Out Mandate, that unfortunately is not something that a Trig TT-21 transponder can do, you need to have a TT-22 because of FAA's silly power requirements for ADS-B Out. And yes you would also likely need a TSO-C145a (or later) GPS source. If your glider is experimental then you have cheaper options (but you need to be careful that say if you connect a commodity GPS to the Trig it won't give you any post 2020 mandate privilege e.g. not allow your glider to enter class B or C airspace... probably not an issue :-)).

TCAS is it's own interrogator (so are the GA oriented "TCAD" systems, some of which evolved to be TCAS I certified), it measures other aircraft's response time to it's interrogations to measure slant distance, and it reads the transponder Mode C replies (or the Mode S equivalent) to get the other aircraft altitudes.

And those TCAS interrogators are one of the reasons why PCAS works at all in areas where you don't have line of sight to a ground based SSR interrogator to cause those transponders to reply... if you are anywhere near popular flight paths. Those TCAS systems are interrogating aircraft out to several tens of miles.

Bonus reading:

TCAS only ever issues Mode C interrogations (or Mode S equivalent), not Mode A for several reasons, one is there is just not much point--the aircrew don't need to know the other aircraft squawk code, and to just cut down on wasting bandwidth, and to avoid confusion about whether a reply from old Mode A/C transponders is a Mode C altitude or a Mode A squawk code.

TCAS II uses a crude predicted time to impact to prioritize threats and when to issue TA and RAs. As the threats get close the TCAS system gets "pretty interested" in the treat and will start hammering away with rapid transponder interrogations. TCAS II works intelligently using selective interrogation of Mode S transponders to cut down on wasting bandwidth. Enough Mode A/C equipped traffic near TCAS based interrogators wastes bandwidth with all the stupid Mode C interrogation replies. That is one reasons that I wish the FAA had said way back in the 1990s that Mode A/C would eventually go away and be replaced with Mode S only...give the industry a clear 1-2 decade roadmap. And that could have lead to a simpler, more affordable and more usable 1090ES only ADS-B system in the USA. Organizations like AOPA lobbying for keeping Mode A/C helped encourage the complex dual-link mess we ended up with.

I would expect that the PowerFlarm NMEA to Trig for ADSB Out will be a popular configuration for anyone with an experimental glider.

Other than making up a cable to go from the PowerFlarm to the remote unit on the Trig is there any testing requirement similar to the Biannual Transponder check that would be required?

On Friday, April 3, 2015 at 1:53:32 PM UTC-7, wrote:
I would expect that the PowerFlarm NMEA to Trig for ADSB Out will be a popular configuration for anyone with an experimental glider.

Other than making up a cable to go from the PowerFlarm to the remote unit on the Trig is there any testing requirement similar to the Biannual Transponder check that would be required?

You are in the wild wild west. You are not meeting any requirement and so not required to do any additional tests that I am aware of besides maintaining the transponder biannual tests. But you better be damn sure to set the GPS SIL parameter and other information correctly... check with Trig and/or their dealers and/or your avionics shop to make sure you have the latest instructions on setting this up.

It will be interesting to see how long a range people see in practice between their Trig transponders with 1090ES Out and PowerFLARM 1090ES In. And 1090ES Out in gliders *might* get interesting for club/FBO/crew tracking.

The dual-link coverage mess with TIS-B and ADS-R is well a mess. If you have an ADS-B receiver capable of receiving TIS-B or ADS-R (like a Garmin ADS-B portable receiver) then you also need to set the appropriate ADS-B out capability code bits in the Trig. It really does not matter with a PowerFLARM since they can't receive ADS-R or TIS-B. I suspect the FAA would really prefer that not set unless you can really have that receive capability--but I'm not sure how seriously they would care. And at some time the threat seems to be non-compliant ADS-B Out won't trigger ADS-R and TIS-B services anyhow.

Amazing how big a mess the FAA has made of the ADS-B thing isn't it? It seems like it had the potential to streamline things and provide useful situational awareness about other traffic with a relatively simple and inexpensive device - sort of a like a universal implementation of FLARM-like technology in all aircraft. So much for that.

My club held off on FLARM for a couple of years as some members thought that ADS-B would make it redundant. We're now installing it to club ships and the tow planes as funds allow and many of the privately owned gliders have it. In my case all it took was one flight to be convinced of the usefulness of FLARM and I was a bit skeptical of its value in our location at first.