On Wednesday, October 3, 2018 at 5:47:07 PM UTC-5, Dan Marotta wrote:

....Â* Flarm is not mandatory in the US except in SSA sanctioned contests (I think)....
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Dan, 5J

Nope, not mandatory in US contests. Encouraged, and if you have it, they can tell you in advance of the contest what mode(s) are not permitted or are required. But the device itself is not required. Williams Soaring has been very generously providing a rental pool of portable FLARM units at a very reasonable cost to the user. I think this has helped a few people see the benefits of the device, and may have helped increase market penetration a bit.

Steve Leonard