On Wednesday, July 31, 2019 at 11:28:04 AM UTC-5, wrote:
Having flown (170B) with ADSB in for the past 5 years, and PowerFlarm for well over that in my Sailplane a couple of observations. 1. ADSB is great for seeing traffic a long way away and therefore can plan accordlingly. It is not very useful in a very busy controlled traffic pattern such as KPRC where I fly mostly. 2. I would not trade my PowerFlarm in the glider for anything. It has saved my bacon (especially at contests) more times than I can count. Busy thermals aside, I have had several alerts on incoming finishes far enough in advance to be able to calmly and clearly manuver away from conflict. I did install a transponder so I can be seen by GA with ADSB in. Is there a need for ADSB in or out for the glider? For me the lack of funds, power, and panel space made the choice clear. PowerFlarm first, Transponder second to be "seen" by GA and commercial traffic, ADSB out last and only if its cost comes down significantly. IMHO

Cliff Hilty CH ASW27 C170B

Having a transponder is very helpful in making you visible to TCAS equipped airliners. It will also make you visible to ADS-B IN & OUT equipped GA aircraft if you are high enough to be seen by ATC radar, AND the GA aircraft is within range of an ADS-B ground station, both of which are not always true, particularly in remote locations at low altitudes, particularly when you are in the traffic pattern at a GA airport.

If you have a Trig transponder, adding ADS-B OUT is a $350 investment in a GPS source. This is a no-brainer given the investment that you have already made.