Gldcomp wrote:

OF COURSE the rare bail-outs are motivated by collision.
Gliders don't fall appart in flight by themselves like ultralights
and other
crazy flying machines.
Gliders are, after all, certified aircraft.

Really? Actually, midair structural failure (usually due to pilot
error) is much more common than midair collision (arguably always due
to pilot error) as a cause of fatal accidents (which is what the
following data are from). I can't think of any obvious reason why
there would be a bias making midairs more surviveable.

This is from a previous post on causes of fatal accidents.

-------------------------------------------------

People have done these studies often enough before, but the breakdown
of fatal accident causes is worth looking at.

I looked at 61 fatal accidents that occurred between 1990 and 2002.

12 accidents, or 20%, resulted from a stall (with or without spin) in
the landing approach.

There were 11 incidents (18%) of collision with terrain during the
in-flight phase, generally along ridgelines. 3 of these were observed
to involve stalling low above the ridgeline; most of the others were
not observed.

An astonishing 9 incidents, or 15%, resulted from in-flight structural
failures. Most involved main spar failure, usually with at least one
wing separating from the fuselage, apparently as a result of
over-stressing the aircraft in flight. 2, however, involved in-flight
control system failures; one where the control stick apparently broke
off (as I understand the report) and one where a swage on one of the
control cables failed.

5 incidents, 8%, resulted from the pilot being incapacitated by heart
attack, stroke, epileptic seizure, drug use, and one apparent
incapacitation of unknown cause (aircraft simply flew into the
ground).

Another 5 incidents resulted from spins from altitude without
recovery. These are difficult to explain, especially since some of
the pilots were highly experienced. However, one high-spin glider had
its CG clearly aft of limits.

There were 4 incidents each of
- elevator/tailplane not connected
- stall on takeoff (premature termination of tow or self-launch)
- collision with terrain while attempting to land (3 of the 4 were
landouts)

There were 2 incidents each of
- midair collision
- loss of control on takeoff
- pilot killed by wire during landing

And there was one incident in which it is clear the pilot attempted to
bail out (for reasons unknown) but was apparently incapacitated when
struck by the canopy.

Here are the things that struck me:

1. Sure enough, we have lots of landing-phase stall/spin fatalities
2. Reading between the lines a little, we probably have a very similar
number of ridge-soaring fatalities.
3. We don't talk much about overstressing the aircraft, but there's a
great deal of that going on.
4. Distraction seems to be a really big issue: if you lump the landing
phase and takeoff phase stall/spins together you get the picture.
Often (PTT, landout) the cause of the distraction is fairly obvious.
5. Sometimes it's just a day with your name on it: whether it's a
heart attack, a powerline or fence you didn't see, or a wire swage
(essentially un-inspectable) that fails. "Fate comes calling"
accidents seem to be about 20% of fatalities.