Let's introduce some common sense here.

Things can break, collide or in other ways ruin your day. We wear parachutes in
the hope that, one day, should we need to rely on something to save our lives
from a no longer flyable glider, the parachute might do the job. Who cares what
the most common cause of failure is, when considering using a primary safety device.

Some points -
My 33 year old Schempp-hirth glider is under 3000 hours total time (+-2200 at
present)- officially a toddler given the life extensions to 12000. I wonder how
many bits of damage and out of spec things there are on her. She has led an
eventful, "competition plane" life for the first decade of flying. Then spent
years being somewhat neglected and inexpertly flown by a succession of owners
who could only afford a cheap glider. And cheap maintenance I suspect...

I maintain the airframe carefully, inspect and renew what looks tired. I have
had it serviced by the professionals, who rate it as one of the best they have
seen - but I really can't be sure there is no problem lying undetected.

Pilots make mistakes, one of the most experienced pilots I have known wrecked a
Ventus A by getting too close to a CB. He used full airbrake, undercarriage out
and nose progressively steeper. Eventually the elevator folded gracefully onto
the fin. His comment was that, as he kneeled on the seat, it struck him that it
was seven years since he had packed his chute. He wondered if it would open.

Some years ago in Germany a pilot landed after three hours in his Spaatz. The
parachute was uncomfortable, and he discarded it before launching again. Half an
hour later he executed a loop, without noticing my friend and a passenger above
him. They pulled up, but he struck their fuselage with his wingtip - inverted.
Wood and fabric wingtip against steel frame had predictable results. They
watched the Spaatz spiral down from nearly 5000' AGL. He did not survive the impact.

My Pioneer 29' tri-conical flies with me, every time - lumps and all. And yes
that does include flights over five hours. It is 18 years old and getting due
for replacement, and has only ever been open in the riggers shop - personally I
like it that way. But maybe some day I get unlucky, or do something stupid.
Maybe some day it will save my life.

Gldcomp wrote:
Maybe I need to clarify this in other words.
No legislative requirement was ever established to carry parachutes because
airplanes or gliders fall appart in normal flight.
This is a common beginner's instinctive fear, expecially during a recovery
from stall, that the wings will fold and they will drop down like a rock.
Some people get so stressed out and terrorized by the sensation of G's that
they will forever avoid more than 30 degrees of bank so they don't have to
tackle the Gs. There are a lot of pilots like that.
The simple truth is that airplanes and gliders don't do that, UNLESS WE FLY
OUTSIDE THE ENVELOPE (exceed VNE, G-loads, etc), or we sabotage it in some
other fashion such as an ill-executed repair, or controls not properly
connected upon assembly.

I never said one is more survivable than the other.
Notice again what I said : Structural failures is NOT the reason we are
required to wear parachutes (but of course, if they do occur, parachutes
will save the pilot just as well).

Midair Collision is the reason we are required to wear parachutes.
That's all I said.


"Finbar" wrote in message
om...

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.