Walt

Here I'll have a shot. I worry there will be typos here and I'll need to repost. I renumbered the bullets to match the SIL level to try to avoid confusion.

0) SIL=0 (any old NMEA GPS source driving a TT21 or TT22 transponder) provides the following capabilities for your glider -

(I do not recommended, use one of the other options below instead)

- Has all the standard transponder capabilities, including ATC SSR visibility and PCAS, TCAD and TCAS compatibility
- Is visible to portable 1090ES In traffic displays (e.g. a Stratus or Stratux receiver driving EFB software)
- Is visible to PowerFLARM (with ADS-B In Option)
- Is NOT visible to certificated fixed install 1090ES In traffic displays in GA aircraft and above
- Is NOT visible to UAT In equipped aircraft via ADS-R- no ADS-R rebroadcast by the ground infrastructure to those aircraft
- Is shown as a TIS-B target to TIS-B client aircraft when within SSR coverage
- Does NOT makes your glider a client of ADS-B ground based services so you cannot see other traffic vis ADS-R and TIS-B (and remember PowerFLARM does not display ADS-R or TIS-B anyhow)
- Is *NOT* visible to ATC via ADS-B (ATC can still see you when within SSR coverage)
- Does NOT provide flight privilege in airspace in 14 CFR 91.225 that requires ADS-B Out, remembering gliders already have some exemptions there.

1) SIL=1 (A TN72 GPS driving a Trig TT21 or TT22 transponder) this is the "TABS" install and provides the following capabilities for your glider -

- Has all the standard transponder capabilities, including ATC SSR visibility and PCAS, TCAD and TCAS compatibility
- Is visible to portable 1090ES In traffic displays (e.g. a Stratus or Stratux receiver driving EFB software)
- Is visible to PowerFLARM (with ADS-B In Option)
- Is visible to certificated fixed install 1090ES In traffic displays in GA aircraft and above
- Is visible to UAT In equipped aircraft - via ADS-R rebroadcast by the ground infrastructure to suitably equipped client aircraft
- Is NOT shown as a TIS-B target to client aircraft when within SSR coverage (since the system is using ADS-R to show you as a more precise target to those clients)
- Does (if properly configured) make your glider a client of ADS-B ground based services so you can see other traffic vis ADS-R and TIS-B (but remember PowerFLARM does not display ADS-R or TIS-B traffic)
- Is NOT visible to ATC via ADS-B (ATC can still see you when within SSR coverage)
- Does NOT provide flight privilege in airspace in 14 CFR 91.225 that requires ADS-B Out, remembering gliders already have some exemptions there.

You would only do this install in a type certified glider where the TN70 option was too expensive or the slightly larger GPS case could not fit (I hope folks would work out how to make it fit). Or in type certified or experimental glider if you had a TT21 and did not want to have it upgraded to a TT22. In an experimental glider you can just use a TN72 GPS to do full 2020 Compliance/SIL=3 which you can't do in a type certified glider since the TN72 GPS is not TSO-C145 approved but the TN70 GPS is.

3) SIL=3 (Trig TT22 (not TT21) with either a TN72 GPS in an experimental glider or TN70 GPS in a type certified glider). This is a fully 14 CFR 91.227 2020 ADS-B Out compliant system and provides the following capabilities for your glider -

- Has all the standard transponder capabilities, including ATC SSR visibility and PCAS, TCAD and TCAS compatibility.
- Is visible to portable 1090ES In traffic displays (e.g. a Stratus or Stratux receiver driving EFB software).
- Is visible to PowerFLARM (with ADS-B In Option)
- Is visible to certificated fixed install 1090ES In traffic displays in GA aircraft and above
- Is visible to UAT In equipped aircraft - via ADS-R rebroadcast by the ground infrastructure to suitably equipped client aircraft
- Is NOT shown as a TIS-B target to client aircraft when within SSR coverage (since the system is using ADS-R to show you as a more precise target to those clients)
- Does (if properly configured) make your glider a client of ADS-B ground based services so you can see other traffic vis ADS-R and TIS-B (but remember PowerFLARM cannot display ADS-R or TIS-B traffic).
- Is visible to ATC via ADS-B (including outside of SSR coverage)
- Does provide flight privilege in airspace in 14 CFR 91.225 that requires ADS-B Out, remembering gliders already have some exemptions there.

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I'm still wondering if ... the TABS system will allow us to be seen by ATC and get clearances to transit restricted or CLASS B,C airspace. If not, I'd have to go for the more expensive TN-70 ... full compliant.

TABS is not 14 CFR 91.227 complaint so does not give you any flight privileges in airspace that requires ADS-B Out in 14 CFR 91.225. So TABS should not ever have been though of as an option there. It's a system really "engineered" (technically and regulation wise) to provide aircraft-aircraft traffic awareness, not ATC surveillance.

And in practice, as far as I am aware (and noted in the lists above) the ATC systems are just not configured to allow ATC to see SIL=1 targets. They only display SIL=3. ATC will still see you via SSR when within SSR coverage. Lack of ATC visibility may make TABS not so appealing for many folks. For others TABS may be a nice easier option to provide visibility to GA aircraft in busy areas (especially where ATC can see you via SSR anyhow) and especially if you are combining with a traffic display that can show you ADS-R and TIS-B traffic.

If 2020 ADS-B Out airspace flight privileges is one of the things you want and you have a type certified glider then a TN70+TT22 is what you should be installing. A few of those install have happened and more are in progress. You or your A&P may want to talk to me before getting started, it's actually pretty easy, I mostly just want to make sure people don't make it more complex than it needs to be.

Are we having fun yet? Remember I'm just reporting how it works, I didn't design the damned thing. :-)

On Friday, December 14, 2018 at 7:30:25 PM UTC-8, WaltWX wrote:
Daryl,

I'm still a bit confused about SIL=0 , SIL=1 and SIL=3

1) SIL=0 means that it will not trigger the ADS-R or TIS-B. Only FLARM with ADS-B will see these targets. ATC will not

2) SIL=1 (TABs system TN-72 attached to Trig). This will trigger ADS-R and TIS-B ... will ATC controllers also see us?

3) SIL=3 FULL 2020 ADS-B Out compliant.

Did I get this right?

I'm still wondering if option 2) the TABS system will allow us to be seen by ATC and get clearances to transit restricted or CLASS B,C airspace. If not, I'd have to go for the more expensive TN-70 ... full compliant.

Walt Rogers