Do your straps up tightly for winch launches!

For the full report see the following URL
http://www.aaib.dft.gov.uk/publicati...ber_6 56_.cfm



Bert Willing wrote:
Doug,

the reading of an ASI is very rarely connected to winch launch accidents,
and certainly not in the initial climb.
Sliding back in the seat (or movement of a seatpan) during initial rotation
has already claimed a number of lives.

Bert

"Doug Haluza" wrote in message
oups.com...
Derek Copeland wrote:
Wouldn't the exact effect depend on the relative areas
of the pot pitot and the usually very small holes in
the T.E. probe? The AAIB are normally very thorough
in their investigations, so I am happy to believe them,
and that this error was not the primary cause of the
accident. Neither am I recommending that you should
connect your instruments up in this way.
No, the area of the openings would not matter, unless there was a
significant leak.

If your description is correct, then I would not assume that the
primary cause was the straps, which as you point out could not be
conclusively determined due to post impact damage. Can you check the
report again and make sure you have correctly reported the results?





--

Phil Collin
Partner Manager
T: 0870 861 0 300
E:
W: www.voicehost.co.uk

Looking at the diagram of the instrument layout in
this glider, it would appear that the total energy
tube was connected to the fuselage statics and then
in turn to all the pressure instruments. I would guess
that effect of the total energy tube on the ASI would
therefore be greatly reduced due to leakage through
the normal static holes.

Derek Copeland


At 10:06 18 October 2006, Phil Collin wrote:
For the full report see the following URL
http://www.aaib.dft.gov.uk/publicati...ptember_2006/g
laser_dirks_dg600_glider__bga_3445__tail_number_ 656_.cfm



Bert Willing wrote:
Doug,

the reading of an ASI is very rarely connected to
winch launch accidents,
and certainly not in the initial climb.
Sliding back in the seat (or movement of a seatpan)
during initial rotation
has already claimed a number of lives.

Bert

'Doug Haluza' wrote in message
oups.com...
Derek Copeland wrote:
Wouldn't the exact effect depend on the relative areas
of the pot pitot and the usually very small holes
in
the T.E. probe? The AAIB are normally very thorough
in their investigations, so I am happy to believe
them,
and that this error was not the primary cause of the
accident. Neither am I recommending that you should
connect your instruments up in this way.
No, the area of the openings would not matter, unless
there was a
significant leak.

If your description is correct, then I would not assume
that the
primary cause was the straps, which as you point out
could not be
conclusively determined due to post impact damage.
Can you check the
report again and make sure you have correctly reported
the results?





--

Phil Collin
Partner Manager
T: 0870 861 0 300
E:
W: www.voicehost.co.uk

This is somewhat analagous to reported accidents by
Cessna pilots on takeoff; if the adjustable seats
are not properly locked in their rails the seat can
slide backward, making it impossible to push the yoke
forward.

Perhaps we need a two-point attachment for each of
the shoulder straps -- the one above the shoulders
that already is in place and which keeps the body from
being thrown forward, plus a second one from be bottom
of the seat pan, and which would prevent the body from
moving upward and aft. This second strap could also
protect against cranial collision with the canopy.


Anyone for seven-point harness?

At 09:30 18 October 2006, Bert Willing wrote:
Doug,

the reading of an ASI is very rarely connected to winch
launch accidents,
and certainly not in the initial climb.
Sliding back in the seat (or movement of a seatpan)
during initial rotation
has already claimed a number of lives.

Bert

'Doug Haluza' wrote in message
roups.com...

Derek Copeland wrote:
Wouldn't the exact effect depend on the relative areas
of the pot pitot and the usually very small holes
in
the T.E. probe? The AAIB are normally very thorough
in their investigations, so I am happy to believe
them,
and that this error was not the primary cause of the
accident. Neither am I recommending that you should
connect your instruments up in this way.

No, the area of the openings would not matter, unless
there was a
significant leak.

If your description is correct, then I would not assume
that the
primary cause was the straps, which as you point out
could not be
conclusively determined due to post impact damage.
Can you check the
report again and make sure you have correctly reported
the results?

I guess we just need to secure the shoulder straps properly ? ...

"Nyal Williams" wrote in message
...
This is somewhat analagous to reported accidents by
Cessna pilots on takeoff; if the adjustable seats
are not properly locked in their rails the seat can
slide backward, making it impossible to push the yoke
forward.

Perhaps we need a two-point attachment for each of
the shoulder straps -- the one above the shoulders
that already is in place and which keeps the body from
being thrown forward, plus a second one from be bottom
of the seat pan, and which would prevent the body from
moving upward and aft. This second strap could also
protect against cranial collision with the canopy.


Anyone for seven-point harness?

At 09:30 18 October 2006, Bert Willing wrote:
Doug,

the reading of an ASI is very rarely connected to winch
launch accidents,
and certainly not in the initial climb.
Sliding back in the seat (or movement of a seatpan)
during initial rotation
has already claimed a number of lives.

Bert

'Doug Haluza' wrote in message
groups.com...

Derek Copeland wrote:
Wouldn't the exact effect depend on the relative areas
of the pot pitot and the usually very small holes
in
the T.E. probe? The AAIB are normally very thorough
in their investigations, so I am happy to believe
them,
and that this error was not the primary cause of the
accident. Neither am I recommending that you should
connect your instruments up in this way.

No, the area of the openings would not matter, unless
there was a
significant leak.

If your description is correct, then I would not assume
that the
primary cause was the straps, which as you point out
could not be
conclusively determined due to post impact damage.
Can you check the
report again and make sure you have correctly reported
the results?

"Nyal Williams" wrote in message
...
This is somewhat analagous to reported accidents by
Cessna pilots on takeoff; if the adjustable seats
are not properly locked in their rails the seat can
slide backward, making it impossible to push the yoke
forward.

That brings back nightmares. I had a Cessna 180 seat come off badly worn
tracks on takeoff. Somehow, I was able to scramble into the right front
seat before crashing.

Bill Daniels

Bert, I think you must not have read all this thread;
it was pointed out that shoulder strap connections
are too high and, while preventing the upper body from
going forward, do not prevent an upward and aft movement.
With current setups, no amount of tightening will
prevent this for short/small persons.


At 14:42 19 October 2006, Bert Willing wrote:
I guess we just need to secure the shoulder straps
properly ? ...

'Nyal Williams' wrote in message
...
This is somewhat analagous to reported accidents by
Cessna pilots on takeoff; if the adjustable seats
are not properly locked in their rails the seat can
slide backward, making it impossible to push the yoke
forward.

Perhaps we need a two-point attachment for each of
the shoulder straps -- the one above the shoulders
that already is in place and which keeps the body
from
being thrown forward, plus a second one from be bottom
of the seat pan, and which would prevent the body
from
moving upward and aft. This second strap could also
protect against cranial collision with the canopy.


Anyone for seven-point harness?

At 09:30 18 October 2006, Bert Willing wrote:
Doug,

the reading of an ASI is very rarely connected to winch
launch accidents,
and certainly not in the initial climb.
Sliding back in the seat (or movement of a seatpan)
during initial rotation
has already claimed a number of lives.

Bert

'Doug Haluza' wrote in message
egroups.com...

Derek Copeland wrote:
Wouldn't the exact effect depend on the relative areas
of the pot pitot and the usually very small holes
in
the T.E. probe? The AAIB are normally very thorough
in their investigations, so I am happy to believe
them,
and that this error was not the primary cause of the
accident. Neither am I recommending that you should
connect your instruments up in this way.

No, the area of the openings would not matter, unless
there was a
significant leak.

If your description is correct, then I would not assume
that the
primary cause was the straps, which as you point out
could not be
conclusively determined due to post impact damage.
Can you check the
report again and make sure you have correctly reported
the results?

Nyal Williams wrote:

Perhaps we need a two-point attachment for each of
the shoulder straps -- the one above the shoulders
that already is in place and which keeps the body from
being thrown forward, plus a second one from be bottom
of the seat pan, and which would prevent the body from
moving upward and aft. This second strap could also
protect against cranial collision with the canopy.

Just be wary of where the shoulder straps attach in the glider. If they
are anchored below shoulder height there's no problem.
ASW-19/Pegase/ASW-20 and Libelle are OK from this respect, as are Juniors.

Some gliders need careful checking because the exact seat arrangement
matters: Some of the early Discii, those fitted with a padded ply seat
back pivoted on a horizontal rod about half way up, have the strap
anchors set too high and you can float up slightly no matter how tight
the straps are. I think the straps run over the top of the seat back
which stops them pulling down on your shoulders quite hard enough.
However, the later models with a shaped glass fibre seat back that
pivots at the bottom don't show this problem.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Nyal, I do have read this thread.
If the attachment point of the shoulder straps are too high, a thin layer of
foam or rubber on the seat pan is all what's needed.
Having double attachment points on the shoulder straps is big means to solve
an easily solved problem - you go through a certification loop, you need to
think about egress restrictions and all this stuff.

"Nyal Williams" wrote in message
...
Bert, I think you must not have read all this thread;
it was pointed out that shoulder strap connections
are too high and, while preventing the upper body from
going forward, do not prevent an upward and aft movement.
With current setups, no amount of tightening will
prevent this for short/small persons.


At 14:42 19 October 2006, Bert Willing wrote:
I guess we just need to secure the shoulder straps
properly ? ...

'Nyal Williams' wrote in message
...
This is somewhat analagous to reported accidents by
Cessna pilots on takeoff; if the adjustable seats
are not properly locked in their rails the seat can
slide backward, making it impossible to push the yoke
forward.

Perhaps we need a two-point attachment for each of
the shoulder straps -- the one above the shoulders
that already is in place and which keeps the body
from
being thrown forward, plus a second one from be bottom
of the seat pan, and which would prevent the body
from
moving upward and aft. This second strap could also
protect against cranial collision with the canopy.


Anyone for seven-point harness?

At 09:30 18 October 2006, Bert Willing wrote:
Doug,

the reading of an ASI is very rarely connected to winch
launch accidents,
and certainly not in the initial climb.
Sliding back in the seat (or movement of a seatpan)
during initial rotation
has already claimed a number of lives.

Bert

'Doug Haluza' wrote in message
legroups.com...

Derek Copeland wrote:
Wouldn't the exact effect depend on the relative areas
of the pot pitot and the usually very small holes
in
the T.E. probe? The AAIB are normally very thorough
in their investigations, so I am happy to believe
them,
and that this error was not the primary cause of the
accident. Neither am I recommending that you should
connect your instruments up in this way.

No, the area of the openings would not matter, unless
there was a
significant leak.

If your description is correct, then I would not assume
that the
primary cause was the straps, which as you point out
could not be
conclusively determined due to post impact damage.
Can you check the
report again and make sure you have correctly reported
the results?

"Nyal Williams" wrote in message
...
This is somewhat analagous to reported accidents by
Cessna pilots on takeoff; if the adjustable seats
are not properly locked in their rails the seat can
slide backward, making it impossible to push the yoke
forward.

Perhaps we need a two-point attachment for each of
the shoulder straps -- the one above the shoulders
that already is in place and which keeps the body from
being thrown forward, plus a second one from be bottom
of the seat pan, and which would prevent the body from
moving upward and aft. This second strap could also
protect against cranial collision with the canopy.


Anyone for seven-point harness?

I've been reading this, and I wonder if you couldn't just sew some straps to
the back side of the existing straps, then bring those down to a rectangle
of ballistic cloth that would lay on and more-or-less cover the seat back
and seat pan.
The higher the nose rotates, the more your weight would tend to squeeze the
ballistic cloth between your parachute and the seat back.

Tim Ward