USA-Parachute Repack Change?

Mark,

'Rather we are discussing whether
the increase in impact injuries is so small, or
negligible, as to be overcome by the benefit of wearing

parachutes for situations where they are a benefit'

When you said that it was precisely the parallel.
The number of motor accidents of a type where the
seat belt or airbag causes more injury than they prevent
is dwarfed by the number in which they save injury
- and I would be totally amazed if the same were not
true for parachutes in gliders.

Apart from anything else far more glider impacts are
closer to the line of the pilot's back than at right
angles to it. That's why the cockpit crash tests
are done in roughly that direction and why submarining
is a major issue.

I think this is your parallel to my recent String Theory:-)

John



At 08:00 22 January 2005, Mark James Boyd wrote:
I don't see the parallel here. Pilot parachutes were
never
intended to reduce injury during a glider impact with
terrain.
Parachute presence during such an impact certainly
doesn't DECREASE injury. Rather we are discussing
whether
the increase in impact injuries is so small, or
negligible, as to be overcome by the benefit of wearing

parachutes for situations where they are a benefit.


In article ,
John Galloway wrote:
. like being better not to wear seat belts in a car
- or have an air bag - because they have been known
to cause injury?

John Galloway

At 23:30 21 January 2005, Mark James Boyd wrote:
In article ,
Stewart Kissel wrote:
Does having an extra 20 pounds behind you during an
impact of more than 20 Gs cause enough additional
stress to measurably increase the chance of
death in an accident?

As opposed to that 20 pounds of silk over your head
allowing you to float down?

EXACTLY! If you are more likely to
be in a impact where the extra 20
pounds is the difference between life and death,
than to be in a situation where parachuting is
the only option, then wearing a chute is
something to consider.

So how many chute saves have there been compared
to fatal accidents where the pilot almost
survived? If a 20 pound chute adds 4% to impact morbidity,
and lifesaving use of the chute only happens one time
for every 50 impact crashes, then there are things
to
consider.

I'm not talking about situations where wearing or not
wearing seems pretty clear. Competitions, aerobatics,
test
flights, formation flight may be
pretty hard to argue. And pattern tows, winch launches
in unsoarable weather seem the same way.

But what about ridge soaring alone on a
day away from MTRs, nobody else around, in a
well established sturdy glider?

I wonder, because I have a parachute, and I tend to
fly in an isolated area, with no MTRs and no
company. And I read Kempton Izuno's stuff about
wearing a chute on a wave day and wondering
about being dragged at 40 knots along the ground
if he bailed.

Sure, if you gotta have it to save your life,
then you got to have it. But for every chute
save, how many impact fatalities have there been?
How many of these had a chute as a contributing
factor because they increase effective BMI?

I don't know the answer. But one part of it comes
from the ratio of bailouts to fatal impacts.
I'd really like to see stats on that...
--

------------+
Mark J. Boyd





--

------------+
Mark J. Boyd

That's one of the most stupid argument against parachutes I ever heared...

--
Bert Willing

ASW20 "TW"


"Mark James Boyd" a écrit dans le message de news:
41f186bd$1@darkstar...
In article ,
Stewart Kissel wrote:
Does having an extra 20 pounds behind you during an
impact of more than 20 Gs cause enough additional
stress to measurably increase the chance of
death in an accident?

As opposed to that 20 pounds of silk over your head
allowing you to float down?

EXACTLY! If you are more likely to
be in a impact where the extra 20
pounds is the difference between life and death,
than to be in a situation where parachuting is
the only option, then wearing a chute is
something to consider.

So how many chute saves have there been compared
to fatal accidents where the pilot almost
survived? If a 20 pound chute adds 4% to impact morbidity,
and lifesaving use of the chute only happens one time
for every 50 impact crashes, then there are things to
consider.

I'm not talking about situations where wearing or not
wearing seems pretty clear. Competitions, aerobatics, test
flights, formation flight may be
pretty hard to argue. And pattern tows, winch launches
in unsoarable weather seem the same way.

But what about ridge soaring alone on a
day away from MTRs, nobody else around, in a
well established sturdy glider?

I wonder, because I have a parachute, and I tend to
fly in an isolated area, with no MTRs and no
company. And I read Kempton Izuno's stuff about
wearing a chute on a wave day and wondering
about being dragged at 40 knots along the ground
if he bailed.

Sure, if you gotta have it to save your life,
then you got to have it. But for every chute
save, how many impact fatalities have there been?
How many of these had a chute as a contributing
factor because they increase effective BMI?

I don't know the answer. But one part of it comes
from the ratio of bailouts to fatal impacts.
I'd really like to see stats on that...
--

------------+
Mark J. Boyd

Just for the interest of those who are not aware of
the work of English pilot, Dr Tony Segal, on glider
pilot fatalities and injuries - there is a series of
6 very detailed articles written by him on the basis
of his research in the Gliding Magazine archive starting
he

http://www.glidermagazine.com/FeatureArticle.asp?id=68

This series is well worth revisiting. Statistically,
spinal injuries from downward impacts are the main
concern for we (aging) glider pilots.

He is still the man to ask and is presenting a lecture
on the subject in a couple of weeks at Boscombe Down:

http://www.raes.org.uk/raes/division...nch.asp?sessid
=&branch=12

John Galloway

So from the broader perspective of whether a "safety" device
contributes to safety ultimately or reduces it, yes, I
see there is a parallel. I was thinking you were drawing
a parallel in another way, which you weren't.

From reviewing the articles, and what you and Eric said, I
think the combined ideas are that:

1) The spinal compression axis is far more of a factor than
the forward momentum.

2) Parachute weight doesn't increase compression
noticably along the spinal axis (parachute weight doesn't
contribute to submarining significantly).

3) During the impact along that axis, the paracute weight
forces are borne almost entirely by the seat frame under it
rather than by the pilot.

So based on this, the extra weight of a parachute has
perhaps some effect, but this effect is negligible
in sailplane terrain impact accidents.

The key difference here is how the weight causes effects
differently in a car vs. a sailplane. The semi-reclined
sailplane seat position is significantly different than
in most automobiles.

Does this sum up what you all seem to have said?
Is there anything else I missed?

In article ,
John Galloway wrote:
Mark,

'Rather we are discussing whether
the increase in impact injuries is so small, or
negligible, as to be overcome by the benefit of wearing

parachutes for situations where they are a benefit'

When you said that it was precisely the parallel.
The number of motor accidents of a type where the
seat belt or airbag causes more injury than they prevent
is dwarfed by the number in which they save injury
- and I would be totally amazed if the same were not
true for parachutes in gliders.

Apart from anything else far more glider impacts are
closer to the line of the pilot's back than at right
angles to it. That's why the cockpit crash tests
are done in roughly that direction and why submarining
is a major issue.

I think this is your parallel to my recent String Theory:-)

John



At 08:00 22 January 2005, Mark James Boyd wrote:
I don't see the parallel here. Pilot parachutes were
never
intended to reduce injury during a glider impact with
terrain.
Parachute presence during such an impact certainly
doesn't DECREASE injury. Rather we are discussing
whether
the increase in impact injuries is so small, or
negligible, as to be overcome by the benefit of wearing

parachutes for situations where they are a benefit.


In article ,
John Galloway wrote:
. like being better not to wear seat belts in a car
- or have an air bag - because they have been known
to cause injury?

John Galloway

At 23:30 21 January 2005, Mark James Boyd wrote:
In article ,
Stewart Kissel wrote:
Does having an extra 20 pounds behind you during an
impact of more than 20 Gs cause enough additional
stress to measurably increase the chance of
death in an accident?

As opposed to that 20 pounds of silk over your head
allowing you to float down?

EXACTLY! If you are more likely to
be in a impact where the extra 20
pounds is the difference between life and death,
than to be in a situation where parachuting is
the only option, then wearing a chute is
something to consider.

So how many chute saves have there been compared
to fatal accidents where the pilot almost
survived? If a 20 pound chute adds 4% to impact morbidity,
and lifesaving use of the chute only happens one time
for every 50 impact crashes, then there are things
to
consider.

I'm not talking about situations where wearing or not
wearing seems pretty clear. Competitions, aerobatics,
test
flights, formation flight may be
pretty hard to argue. And pattern tows, winch launches
in unsoarable weather seem the same way.

But what about ridge soaring alone on a
day away from MTRs, nobody else around, in a
well established sturdy glider?

I wonder, because I have a parachute, and I tend to
fly in an isolated area, with no MTRs and no
company. And I read Kempton Izuno's stuff about
wearing a chute on a wave day and wondering
about being dragged at 40 knots along the ground
if he bailed.

Sure, if you gotta have it to save your life,
then you got to have it. But for every chute
save, how many impact fatalities have there been?
How many of these had a chute as a contributing
factor because they increase effective BMI?

I don't know the answer. But one part of it comes
from the ratio of bailouts to fatal impacts.
I'd really like to see stats on that...
--

------------+
Mark J. Boyd





--

------------+
Mark J. Boyd





--

------------+
Mark J. Boyd

Mark James Boyd wrote:
So from the broader perspective of whether a "safety" device
contributes to safety ultimately or reduces it, yes, I
see there is a parallel. I was thinking you were drawing
a parallel in another way, which you weren't.

From reviewing the articles, and what you and Eric said, I
think the combined ideas are that:

1) The spinal compression axis is far more of a factor than
the forward momentum.

2) Parachute weight doesn't increase compression
noticably along the spinal axis (parachute weight doesn't
contribute to submarining significantly).

3) During the impact along that axis, the paracute weight
forces are borne almost entirely by the seat frame under it
rather than by the pilot.

So based on this, the extra weight of a parachute has
perhaps some effect, but this effect is negligible
in sailplane terrain impact accidents.

The key difference here is how the weight causes effects
differently in a car vs. a sailplane. The semi-reclined
sailplane seat position is significantly different than
in most automobiles.

Does this sum up what you all seem to have said?
Is there anything else I missed?

It does for me.


--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

Mark,

Sorry for the slow reply. Yes - that seems to be a
fair summary.

John

At 05:00 23 January 2005, Mark James Boyd wrote:
So from the broader perspective of whether a 'safety'
device
contributes to safety ultimately or reduces it, yes,
I
see there is a parallel. I was thinking you were drawing
a parallel in another way, which you weren't.

From reviewing the articles, and what you and Eric
said, I
think the combined ideas are that:

1) The spinal compression axis is far more of a factor
than
the forward momentum.

2) Parachute weight doesn't increase compression
noticably along the spinal axis (parachute weight doesn't

contribute to submarining significantly).

3) During the impact along that axis, the paracute
weight
forces are borne almost entirely by the seat frame
under it
rather than by the pilot.

So based on this, the extra weight of a parachute has
perhaps some effect, but this effect is negligible
in sailplane terrain impact accidents.

The key difference here is how the weight causes effects
differently in a car vs. a sailplane. The semi-reclined
sailplane seat position is significantly different
than
in most automobiles.

Does this sum up what you all seem to have said?
Is there anything else I missed?

In article ,
John Galloway wrote:
Mark,

'Rather we are discussing whether
the increase in impact injuries is so small, or
negligible, as to be overcome by the benefit of wearing

parachutes for situations where they are a benefit'

When you said that it was precisely the parallel.
The number of motor accidents of a type where the
seat belt or airbag causes more injury than they prevent
is dwarfed by the number in which they save injury
- and I would be totally amazed if the same were not
true for parachutes in gliders.

Apart from anything else far more glider impacts are
closer to the line of the pilot's back than at right
angles to it. That's why the cockpit crash tests
are done in roughly that direction and why submarining
is a major issue.

I think this is your parallel to my recent String Theory:-)

John



At 08:00 22 January 2005, Mark James Boyd wrote:
I don't see the parallel here. Pilot parachutes were
never
intended to reduce injury during a glider impact with
terrain.
Parachute presence during such an impact certainly
doesn't DECREASE injury. Rather we are discussing
whether
the increase in impact injuries is so small, or
negligible, as to be overcome by the benefit of wearing

parachutes for situations where they are a benefit.


In article ,
John Galloway wrote:
. like being better not to wear seat belts in a car
- or have an air bag - because they have been known
to cause injury?

John Galloway

At 23:30 21 January 2005, Mark James Boyd wrote:
In article ,
Stewart Kissel wrote:
Does having an extra 20 pounds behind you during
an
impact of more than 20 Gs cause enough additional

stress to measurably increase the chance of
death in an accident?

As opposed to that 20 pounds of silk over your
head
allowing you to float down?

EXACTLY! If you are more likely to
be in a impact where the extra 20
pounds is the difference between life and death,
than to be in a situation where parachuting is
the only option, then wearing a chute is
something to consider.

So how many chute saves have there been compared
to fatal accidents where the pilot almost
survived? If a 20 pound chute adds 4% to impact morbidity,
and lifesaving use of the chute only happens one time
for every 50 impact crashes, then there are things
to
consider.

I'm not talking about situations where wearing or not
wearing seems pretty clear. Competitions, aerobatics,
test
flights, formation flight may be
pretty hard to argue. And pattern tows, winch launches
in unsoarable weather seem the same way.

But what about ridge soaring alone on a
day away from MTRs, nobody else around, in a
well established sturdy glider?

I wonder, because I have a parachute, and I tend to
fly in an isolated area, with no MTRs and no
company. And I read Kempton Izuno's stuff about
wearing a chute on a wave day and wondering
about being dragged at 40 knots along the ground
if he bailed.

Sure, if you gotta have it to save your life,
then you got to have it. But for every chute
save, how many impact fatalities have there been?
How many of these had a chute as a contributing
factor because they increase effective BMI?

I don't know the answer. But one part of it comes
from the ratio of bailouts to fatal impacts.
I'd really like to see stats on that...
--

------------+
Mark J. Boyd





--

------------+
Mark J. Boyd





--

------------+
Mark J. Boyd