The discussion of using FLARM in the USA is just so much self
flagulation. I have flown in France and used FLARM. A very nice,
compact, and simple system that is easy to understand while flying.
The primary problem is exactly the same as gliders having a
transponder in the USA. There are many, many gliders flying around
the Alps that do not have FLARM. You get comfortable with responding
to the signals from FLARM and then WHAM...there is a glider headed
right at your nose and no FLARM !

I feel that for the USA it would be a much better course to encourage
the installation of transponders and development of systems that use
transponder technology to do the work of FLARM. These chat groups
seem dominated by people constantly arguing that they won't buy a
transponder because a new system is just over the horizon whether it
is ADS-B or Mode S. The reality that we all see is that the existing
system is going to be it for some time. By working with the existing
system you get gliders to become full fledged members of the aviation
community that exists today. You become better friends with other
traffic because they can see you on their collision avoidance
systems. Having FLARM means you are still invisable to commercial
traffic and the air traffic controllers. It means that instead of
having just two groups of gliders in the USA (with or without
transponders) you create a microscopic group that have FLARM and are
still invisable to the air traffic control system.

Flying around Reno became DRAMATICALLY better after installing a
transponder. AIr traffic control sees you and directs all of their
traffic away from you without any effort on the glider pilot's part.
Commercial traffic and others with "fish finders" happily see you and
avoid without any sweat being shed. Work should be put into small,
modestly expensive collision avoidance systems that use the existing
transponders.

Guy Acheson "DDS"