Darryl said it far better than I could have.Â* What I meant is that I
believe Mode 3A transponders with Mode C are becoming obsolete and, for
all the reasons Darryl said, I agree on the TT-22 from Trig. I've had
one installed for about 8 years and about a year ago added a Trig TN-70
ADS-B Out to it.Â* I highly recommend it.Â* The TT-21 is a couple hundred
dollars less expensive, but it is not approved for 1090ES.Â* I don't know
about UAT.

On 10/12/2019 6:24 PM, Darryl Ramm wrote:
On Saturday, October 12, 2019 at 3:51:31 PM UTC-7, Eric Greenwell wrote:
Dan Marotta wrote on 10/12/2019 7:45 AM:
.... Better, still, the transponder will alert the controlling agency to your
presence.Â* And don't waste your money on a Mode 3A/C transponder. Get Mode S.
How much would a Mode S decrease the pilot's risk, compared to a Mode C (speaking
as a pilot with a Mode C installed, but thinking a Mode S might be more useful)?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
None at all in practice.

And I expect Dan was giving general advice to buy new Mode S transponders, not new Mode C.

Let me try to say it how I would... If you are buying a new transponder for a glider get a Trig TT22. This is very specific advice... "not Mode S", not any other transponder.... There is *no* other compact transponder suitable for use in gliders in the USA that provide you with ADS-B Out options. Becker, Air-Avionics,.... none of them provide a Mode S transponder today that meets the 2020 14 CFR 91.227 technical requirements.

Using a Trig TT22 gives you all the options to upgrade to ADS-B Out if you want to do that now or in future, including TABS or 2020 Compliant ADS-B Out.

But, but, but.. if a Mode C transponder is all you have or can afford that is *great* compared to nothing in environments like flying in the area being discussed. In practice, ground based SSR, TCAS, Military IFF interrogators will see your aircraft just as effectively as if you had a Mode S transponder. If you have ADS-B Out added to a TT22 then more GA aircraft will see you, and ATC may see you in areas normally outside of SSR coverage... although the particular area being discussed has significant holes in it's ADS-B ground receiver coverage as well.

One thing I ask folks who are upgrading older transponders like Becker ATC 4401 Mode C to a Trig TT22 is please find a junior pilot or other active local pilots who don't have or can't afford a transponder and give them your old transponder, or at least give them a deal they can't refuse.



--
Dan, 5J