On Tuesday, July 9, 2013 8:39:53 PM UTC-7, Eric Greenwell wrote:
jfitch wrote, On 7/9/2013 4:24 PM:





Well, A: I don't believe the demographics of glider pilots has

changed much in 20 years. But please find some statistics on that,

I'm interested.



B: from the descriptions of the only 2 fatalities in the NTSB

database, better (or worse) eyesight would have made no difference in

the outcome (though Flarm probably would).



I'm not trying to be dismissive or flippant about this issue, but I

think there is a sort of hysteria about mid air collisions brought on

by the sudden appearance of an elegant technical solution to what is

really quite a small problem. Now everyone must have it, with a

growing body who advocate legal requirement. In fact, there is every

reason to believe that a stall warning buzzer would save many more

glider pilots. This is old technology yet not installed in any glider

that I am aware of. I do not advocate them - you really ought to just

learn to fly the damn glider - but at the same time many of us are

standing in a forest fretting over a particularly small tree.



By all means get a Flarm. But don't then say, "There! I fixed the

glider safety problem." You are statistically just about as likely to

die in a glider with it, as without it. The likelihood of dying due

to being hit mid air by an aging glider pilot strictly because of his

deteriorating vision is about the same as hitting the Powerball

jackpot.



There were a number of glider-glider collisions in the last 20 years

that did not result in fatalities (like Ed Sakeld's a few years ago), so

perhaps we are lucky it's only two in twenty years. And since PowerFlarm

also adds transponder and ADS-B reporting, perhaps the statistics should

be enlarged to include accidents that could have been avoided by those

two technologies (like the airplane/towplane accident in Boulder).



Besides the collision warnings, many pilots will derive some value from

the flight recorder function and the "entertainment" aspect of PowerFlarm..



So, attributing some monetary value to these additional functions lowers

the cost of the glider-glider fatality avoidance function. I can't say

it would become the most cost effective way to spend that money for

glider-glider fatality avoidance, but it certainly makes it cheap enough

I'm happy to spend the money today for value that will accrue for many

years.



--

Eric Greenwell - Washington State, USA (change ".netto" to ".us" to

email me)

- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm

http://tinyurl.com/yb3xywl

The thread started with the idea that old folks in gliders are plowing into young folks in gliders at an alarming rate. This is simply not happening, and not likely to. Yes there have been a few more non fatal mid airs, but still quite a low rate - only 4 or 5 more in twenty years history. Mid air collisions of any type are simply not the low hanging fruit of soaring safety.

I'm not sure the PCAS capability of PowerFlarm is going to be all that useful - but the ADS-B will be, and more so as time goes on. Mid airs between glider and tow plane (there have been more of those than glider-to-glider) would be prevented only if the towplanes have either Flarm or ADS-B. However much of this would also be (and is) accomplished by transponders.

I justified the PFlarm cost by the entertainment and leeching value.