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Old December 18th 15, 08:08 PM posted to rec.aviation.soaring
Darryl Ramm
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Default Garmin GPS 20A with Trig TT22 in Experimental Glider - OK?

On Friday, December 18, 2015 at 11:56:18 AM UTC-8, Darryl Ramm wrote:

OK thanks for the private emails :-) Doh I did not spot the (likely accidental) transposition in Mike's post. To be clear the lower-powered Trig TT-21 does *not* meet the ADS-B out requirements in the USA. You need a higher-powered Trig TT-22 (and certified IFR GPS source). But as I said, TABS devices have lower power requirements so if TABS is adopted a TT-21 should be usable as a TABS device (and that includes triggering all the ADS-B ground infrastructure base services). But since there are no TABS installation or carriage regulations yet we have no real idea about any of this actually happening.


OK and one more... since I see this come up occasionally. The 2020 Carriage ADS-B Out regulations that require a TT-22 (if you wanted to do any install in a certified glider or a complaint install in an experimental glider) and not a (lower power) TT-21 are completely separate from the old needing a higher power (Class 1) transponder over 15,000' regulation. The TT-21 unfortunately does not meet the ADS-B Out power requirements in the USA (a unique issue to the USA because of the reliance on widely space ADS-B ground stations), even below 15,000'.

Bottom line if buying a transponder today in the USA, just get the Trig TT-22. A fine piece of kit. If you don't need a new transponder today (like you have a working Mode C transponder already, just WAIT... and see what happens with FAA regulations and new products entering the market).