Excellent reply!

I tried several keywords and the midairs I found in the NTSB database were
those that I listed. I will accept your assertion that there are more - I
just couldn't find them.

While reading your response regarding Flarm being better than a transponder,
it occurred to me that, where I fly that is just not the case. Due to the
altitudes that we fly, pretty much all powered aircraft have to have
transponders (above 10,000' MSL), and there are probably less than a dozen
of us that venture far from the airport. Our airport is also very lightly
used by power traffic and the cross country pilots usually return late in
the day after all hangars are closed. Our only major concerns are the IFR
arrival and departure routes which are near the airport. So, speaking
purely from my flying situation, a transponder is a far better solution than
a Flarm.

Your situation is, of course, different.

wrote in message
...
On Tuesday, December 10, 2013 10:19:07 AM UTC-8, Dan Marotta wrote:

I used the keywords "midair" and "glider" in my search but there may well
be
others which I missed. My point is that, considering the number of glider
flights conducted in the US, the risk of a midair is extremely low and, in
my opinion, does not warrant the expense, complexity, or distraction of a
collision warning device for most of the glider flying done in the US.
Competition flying is different, of course, as it concentrates so many
gliders in the same airspace. Europe is much more congested and has far
more glider flights than we do and I can see more of a benefit for them.

And, finally, for a good many of us glider pilots, we cannot simply lay
down
for an ASG-29, full panel, and Cobra trailer. For us, the sport is
somewhat
cost driven.


For some reason it is hard to get the NTSB database to cough up all the
incidents. You missed several midairs I know of in the past 5 years or so
including one requiring a bailout and one where one pilot tried to bailout
but was unable to and thankfully was able to land without injury. That
doesn't include a number of scary near misses.

I believe the data shows that midair is the second leading cause of fatality
next to stall-spin/collision with terrain. Glider-glider collision is at
least ten times likely as glider-GA collision and (by the data) infinitely
more likely than glider-air transport collision. If we ever got one of those
it would be ugly and bring the stats up to making glider-glider 100 times
more likely than glider-air transport.

Yes, contests gather gliders and concentrate traffic but if you look at the
some of the work that has been done to accumulate OLC traces into glider
flight path "heat maps" you discover that the combination of topography,
airports, airspace and (especially) lift sources puts gliders in much closer
proximity to each other than you might otherwise think. Gliders tend to
occupy a small, common proportion of the available airspace, even though we
think we are flying just anywhere. This explains why we see more
glider-to-glider collisions than any other kind of glider involved
collision. It raises the question as to whether if forced to trade off
transponder vs Flarm for cost reasons the most bang for the buck really
might be Flarm, even for non-contest flying near terminal areas. The midair
collision data suggests this might well be true since the penetration of
Flarm and transponders in gliders are both low. The equation would only flip
for very small numbers of gliders (5) flying right up against a busy
international airport - though there aren't many of these. I carry both
Flarm and a Mode S, but I realize others feel they can't afford both, just
the way some feel a parachute isn't worth the cost (I believe there also are
fewer successful bailouts than glider-glider midairs - so selling one's
parachute to buy a Flarm may also be a statistically superior solution -
though emotionally I can't imagine anyone making the switch).

In any case, having two, incompatible, Flarm-like technologies is a terrible
idea for the reasons already articulated.

9B