Glider Safety

Alan wrote:

Its not that XC types are getting a certain number of landings... Its
that XC types tend to fly regularly and tend to stick with the sport,
accumulating more time and experience and skill.

The "local fliers" who come out for a sled ride now and then DO NOT
typically go 6 - 10 times; especially not in a single day! In my
experience, a lot of the "local only" or "sled ride" folks come out
once every few weeks or months, take 1 - 3 tows, and then disappear
for another stretch of time. It is the infrequency of their
experience and the lack of regular practice that is the problem - not
the type of flying that they enjoy.


Actually, this is pretty close to my point. These discussions seem
to always include the theme that the XC flyers are the "better" flyers
with some credit to their doing XC. There is no reason a local flyer
cannot be the better flyer, if they get enough practice at it.

I suppose it means what you mean by "better flyer". My observation is
these "local only" pilots tend to have limited ability to handle a
different landing place (like a landout, or even a different airport)
than the home airport, or weather that varies much beyond good (any
thing besides light crosswinds and modest downdrafts in the pattern,
say), or a "panic" situation (inadvertently blown downwind, for
example). It's not surprising that is so, since "local flying" requires
less flying skill, and much less decision making, attention, and
priority setting.

Because their local flying tends to limit the difficulty of the
situations they encounter, they may not be any less safe, but typically,
they are still less capable pilots. It's not a problem, as long as they
enjoy it and limit their exposure to the more difficult conditions they
are not prepared for.

"Enough practice" seems unlikely in such a "local" situation. They might
have a lot of practice, but it's the same thing repeated a hundred
times, not coping with new situations. I certainly experience far
greater requirements on my piloting skill during cross-country flying
than I ever do within gliding distance of my home airport.

--
Eric Greenwell - Washington State, USA (netto to net to email me)

- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm http://tinyurl.com/yb3xywl

- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what you need to know tinyurl.com/yfs7tnz

On Feb 21, 2:04*pm, Andy wrote:
On Feb 21, 2:04*pm, Tom wrote:

The following is the first of a series of newsletters to be sent to
subscribers to my popular newsletter.
This series of newsletters will review:
Accident causes.
FATALITIES PER THOUSAND
Gliders: Approximately 1 in 2,000
*Autos: *Approximately 1 in 6,000

Tom,

I don't doubt the numbers are horrible but can you please clarify
"FATALITIES PER THOUSAND"? *Per thousand what? *Is this registered
gliders, certificated pilots, hours flown, miles flown...?

thanks

Andy

I have the same question - what is the denominator? In fact there are
two denominators required since you also need to specify a time frame
(typically a year).

If the 1 in 2,000 is per glider pilot per year that would be a lot
worse for glider pilots than per hour or per operation - like takeoff
or landing, or per trip in a car. Most pilots spend a lot less time in
their gliders than in their autos and make a lot more car trips than
glider flights.

If the stats are per pilot then you are three times as likely to have
a fatal accident in your glider for an average person. If it's per
hour then you are 2-3 times as likely to have a fatal auto accident in
any given year.

Based on the number of people I know who have died in each activity
I'm betting Tom's stats are per person per year. I've known maybe a
dozen pilots who have been killed in gliders and can't recall a single
auto accident victim that I had met personally.

It also means that over a 40 year soaring career your probability of
being in a fatal accident is around 1 in 50, or 2% - assuming you fly
the average annual amount of hours over the entire period.

9B

It also means that over a 40 year soaring career your probability of
being in a fatal accident is around 1 in 50, or 2% - assuming you fly
the average annual amount of hours over the entire period.

9B




No, it doesn't. The risk isn't cumulative, it's 1:2,000 each year you fly.

I can guarantee that if you have a fatal accident in year 1, your risk
of repeating it in years 2-40 is 0%.

Bear in mind also that more than 3/4 of fatal accidents seem to have
causes within the pilot's own control so that, if you flew perfectly all
the time, you could reduce that risk to more like 1:8,000.

My philosophy is that 1:2,000 is acceptable, and that I will work to get
it nearer 1:8,000. Still more dangerous than autos per hour, but worth it.

Chris Reed wrote:
It also means that over a 40 year soaring career your probability of
being in a fatal accident is around 1 in 50, or 2% - assuming you fly
the average annual amount of hours over the entire period.

9B


No, it doesn't. The risk isn't cumulative, it's 1:2,000 each year you
fly.
True, but 9B said "over 40 year soaring career".

I can guarantee that if you have a fatal accident in year 1, your risk
of repeating it in years 2-40 is 0%.
True, but irrelevant. I also calculate the risk over a 40 year period as
being 2%, assuming the 1 in 2000 chance/year. YMMV.

Chance of not being in an accident each year = (1 - 0.0005) = 0.9995
For 40 years, chance = 0.9995^40 = 0.98

That's 98% chance of not being in an accident. Lots of assumptions, so
maybe not too instructive.
For 40 years, 1 in 8000 gets it down to 99.5% of not being in an accident.

--
Eric Greenwell - Washington State, USA (netto to net to email me)

- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm http://tinyurl.com/yb3xywl

- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what you need to know tinyurl.com/yfs7tnz

Eric Greenwell wrote:
Chris Reed wrote:
It also means that over a 40 year soaring career your probability of
being in a fatal accident is around 1 in 50, or 2% - assuming you fly
the average annual amount of hours over the entire period.

9B


No, it doesn't. The risk isn't cumulative, it's 1:2,000 each year you
fly.
True, but 9B said "over 40 year soaring career".

I can guarantee that if you have a fatal accident in year 1, your risk
of repeating it in years 2-40 is 0%.
True, but irrelevant. I also calculate the risk over a 40 year period as
being 2%, assuming the 1 in 2000 chance/year. YMMV.

Chance of not being in an accident each year = (1 - 0.0005) = 0.9995
For 40 years, chance = 0.9995^40 = 0.98

That's 98% chance of not being in an accident. Lots of assumptions, so
maybe not too instructive.
For 40 years, 1 in 8000 gets it down to 99.5% of not being in an accident.

OK, I'll accept that as a calculation at the beginning of year 1.

However, I've survived 14 years without a fatal accident so far. In the
remaining 26 of my 40 year career (I hope), that gives me a 0.9995 to
the power 26 chance of a fatal accident (0.987, or a 1.3% chance). If I
make it to the end of year 39 I have a 1:2,000 or 0.0005 chance of a
fatal accident in the final year.

I don't think the probability over a flying career helps understand risk
much on an individual basis, though it's useful for insurers and actuaries.

Much better to think that you have a 1:2,000 chance in the coming year,
and work on getting that ratio to improve in your favour.