Towing Accident Rate vs GA?

mattm wrote:
However, I will point out that a student pilot's actions are
considered
to be up to the instructor's judgement, even if the student is flying
solo. The instructor must have suitably trained the student to handle
the flight before turning them loose, and must supervise all their
flights
until their checkride. I think that's part of the NTSB attitude in
the
report, although they don't mention the instructor.

I know the instructor (and I knew the tow pilot and have met the glider
pilot.) The CFIG in fact had flown three flights with me while I was a
glider student. Of the three CFIGs in the club I flew with, he provided the
most detailed feedback and critiques. In fact whereas my primary instructor
considered me ready for solo, but had to travel on the weekend I hoped to
solo, he stepped in and flew three flights with me. But he did not sign me
off for solo. So I would judge his standards higher than the average CFIG
(he happens to be chief pilot for a businesss and pilots a company King Air
for them.)

From the NTSB report,

"Examination of the tow airplane tail hook assembly revealed that the
mounting plate was bent upward and the
heads of two connecting bolts were in contact with the base of the
rudder. The tail hook was intact and remained attached to the mounting
plate. The hook was in the locked position, closed around the tow
ring. The release cable remained attached to the hook and was
continuous to the cockpit release handle. Functional testing of the
tail hook assembly revealed no anomalies, and the assembly functioned
appropriately."

I'm really surprised at the above part of the NTSB report - - my take
is a bit different. I visited the yard where the wreckage was stored,
some weeks after the accident, as I happened to be there on other
business. I was not allowed to take pictures but did examine the
wreckage and in particular, the tow hook assembly. I'm not an expert
on aviation wreckage examination, I am trained in auto accident
investigation.

There were two Schweizer tow hooks mounted to a flat plate, with an
additional mounting hole for a third hook, all side-by-side ( I
understand multiple tow hooks are sometimes used for banner towing.)
The multiple hook mounting plate was attached to the aircraft via what
looked to be an alluminum bar, guessing 1/4" thick by 1.5" wide and
extending back maybe 8" from the rudder post spring mount . . . you
would be correct if you concluded this bar offered minimal resistance
to vertical loads without bending. As the NTSB says, the bar was bent
upwards and had impacted the lower part of the rudder, deforming
bending the bottom bow of the rudder up in the process. Though this
jammed the rudder, given the low altitude and nose down attitude pre-
crash, the jammed rudder probably was not causal.

The upward bend and position of the tow hooks inserted a significant
amout of slack in the tow release cable forward of the hook. This
slack, along with the new geometry or position of the tow hook with
respect to the release cable (i.e. now would be pulling upward on the
release toggle instead of forward as necessary to release the hook),
looked to me like it would have been impossible to release the tow
hook/s from the cockpit, even with no load on the hook. Otherwise the
hook appeared to be functional, just not by the cable (note that I did
not touch or try to operate the hook by hand - - I was only allowed to
look, not touch).

From what I saw, I believe the tow hook installation was inadequate
and unsafe. If it was causative, it was doubtless not the only cause
of this accident, though. It may well be that even if the mount had
been designed with the cutomary strength common in tow planes (rather
than just being adequate for banner towing) that a kiting glider would
still have resulted in the same tragic outcome.

I'm posting this as I think the NTSB overlooked and/or glossed over
the role the bent tow hook mount may have played, and in doing so
missed an opportunity for us to learn from this. As we know even a
properly installed upright Schweizer hook can be difficult to release
with upward loading. If the mount is inadequate (that aluminum bar
comes to mind) and bends up easily, unless the Bowden cable is
installed in such a way that the cable stays in line with the hook
(i.e. perpendicular to the release toggle) and, unless there's a way
for the release lever or mechanism in the cockpit to take up any extra
slack that my be induced by the bent mount, I'd say there's no hope of
releasing whatsoever - - even if the tuggie is right on it.

bumper

On Jan 27, 2:03*am, bumper wrote:
From the NTSB report,

"Examination of the tow airplane tail hook assembly revealed that the
mounting plate was bent upward and the
heads of two connecting bolts were in contact with the base of the
rudder. The tail hook was intact and remained attached to the mounting
plate. The hook was in the locked position, closed around the tow
ring. The release cable remained attached to the hook and was
continuous to the cockpit release handle. Functional testing of the
tail hook assembly revealed no anomalies, and the assembly functioned
appropriately."

I'm really surprised at the above part of the NTSB report - - my take
is a bit different. I visited the yard where the wreckage was stored,
some weeks after the accident, as I happened to be there on other
business. I was not allowed to take pictures but did examine the
wreckage and in particular, the tow hook assembly. I'm not an expert
on aviation wreckage examination, I am trained in auto accident
investigation.

There were two Schweizer tow hooks mounted to a flat plate, with an
additional mounting hole for a third hook, all side-by-side ( I
understand multiple tow hooks are sometimes used for banner towing.)
The multiple hook mounting plate was attached to the aircraft via what
looked to be an alluminum bar, guessing 1/4" thick by 1.5" wide and
extending back maybe 8" from the rudder post spring mount . . . you
would be correct if you concluded this bar offered minimal resistance
to vertical loads without bending. As the NTSB says, the bar was bent
upwards and had impacted the lower part of the rudder, deforming
bending the bottom bow of the rudder up in the process. Though this
jammed the rudder, given the low altitude and nose down attitude pre-
crash, the jammed rudder probably was not causal.

The upward bend and position of the tow hooks inserted a significant
amout of slack in the tow release cable forward of the hook. This
slack, along with the new geometry or position of the tow hook with
respect to the release cable (i.e. now would be pulling upward on the
release toggle instead of forward as necessary to release the hook),
looked to me like it would have been impossible to release the tow
hook/s from the cockpit, even with no load on the hook. Otherwise the
hook appeared to be functional, just not by the cable (note that I did
not touch or try to operate the hook by hand - - I was only allowed to
look, not touch).

From what I saw, I believe the tow hook installation was inadequate
and unsafe. If it was causative, it was doubtless not the only cause
of this accident, though. It may well be that even if the mount had
been designed with the cutomary strength common in tow planes (rather
than just being adequate for banner towing) that a kiting glider would
still have resulted in the same tragic outcome.

I'm posting this as I think the NTSB overlooked and/or glossed over
the role the bent tow hook mount may have played, and in doing so
missed an opportunity for us to learn from this. As we know even a
properly installed upright Schweizer hook can be difficult to release
with upward loading. If the mount is inadequate (that aluminum bar
comes to mind) and bends up easily, unless the Bowden cable is
installed in such a way that the cable stays in line with the hook
(i.e. perpendicular to the release toggle) *and, unless there's a way
for the release lever or mechanism in the cockpit to take up any extra
slack that my be induced by the bent mount, I'd say there's no hope of
releasing whatsoever - - even if the tuggie is right on it.

bumper

Amazing the NTSB overlooked the tow hook installation and completely
disregarded the most likely probable cause - that the tug had an
unrecoverable upset caused the glider being out of position.

This report, and one for a tow fatal at Peoria, AZ, seem to show that
NTSB is completely unfamiliar with the tug upset scenario.

The combination of a 2-33 which requires considerable forward stick
pressure to maintain position on tow, a distracted glider pilot, and a
****ty tug tow hook was a sure set up for another dead tow pilot.

Andy

On Jan 27, 1:03*am, bumper wrote:
From the NTSB report,

"Examination of the tow airplane tail hook assembly revealed that the
mounting plate was bent upward and the
heads of two connecting bolts were in contact with the base of the
rudder. The tail hook was intact and remained attached to the mounting
plate. The hook was in the locked position, closed around the tow
ring. The release cable remained attached to the hook and was
continuous to the cockpit release handle. Functional testing of the
tail hook assembly revealed no anomalies, and the assembly functioned
appropriately."

I'm really surprised at the above part of the NTSB report - - my take
is a bit different. I visited the yard where the wreckage was stored,
some weeks after the accident, as I happened to be there on other
business. I was not allowed to take pictures but did examine the
wreckage and in particular, the tow hook assembly. I'm not an expert
on aviation wreckage examination, I am trained in auto accident
investigation.

There were two Schweizer tow hooks mounted to a flat plate, with an
additional mounting hole for a third hook, all side-by-side ( I
understand multiple tow hooks are sometimes used for banner towing.)
The multiple hook mounting plate was attached to the aircraft via what
looked to be an alluminum bar, guessing 1/4" thick by 1.5" wide and
extending back maybe 8" from the rudder post spring mount . . . you
would be correct if you concluded this bar offered minimal resistance
to vertical loads without bending. As the NTSB says, the bar was bent
upwards and had impacted the lower part of the rudder, deforming
bending the bottom bow of the rudder up in the process. Though this
jammed the rudder, given the low altitude and nose down attitude pre-
crash, the jammed rudder probably was not causal.

The upward bend and position of the tow hooks inserted a significant
amout of slack in the tow release cable forward of the hook. This
slack, along with the new geometry or position of the tow hook with
respect to the release cable (i.e. now would be pulling upward on the
release toggle instead of forward as necessary to release the hook),
looked to me like it would have been impossible to release the tow
hook/s from the cockpit, even with no load on the hook. Otherwise the
hook appeared to be functional, just not by the cable (note that I did
not touch or try to operate the hook by hand - - I was only allowed to
look, not touch).

From what I saw, I believe the tow hook installation was inadequate
and unsafe. If it was causative, it was doubtless not the only cause
of this accident, though. It may well be that even if the mount had
been designed with the cutomary strength common in tow planes (rather
than just being adequate for banner towing) that a kiting glider would
still have resulted in the same tragic outcome.

I'm posting this as I think the NTSB overlooked and/or glossed over
the role the bent tow hook mount may have played, and in doing so
missed an opportunity for us to learn from this. As we know even a
properly installed upright Schweizer hook can be difficult to release
with upward loading. If the mount is inadequate (that aluminum bar
comes to mind) and bends up easily, unless the Bowden cable is
installed in such a way that the cable stays in line with the hook
(i.e. perpendicular to the release toggle) *and, unless there's a way
for the release lever or mechanism in the cockpit to take up any extra
slack that my be induced by the bent mount, I'd say there's no hope of
releasing whatsoever - - even if the tuggie is right on it.

bumper

I guess this largely depends on what exact post-crash functional
testing of the release mechanism that the NTSB did. Did they test with
the tow hook loaded up with a rope at appropriate (high) angles?

Does anybody know if the aluminum (or could it be duralium - either
way it sounds surprisingly weak to bending) mount was a part of a kit
or was custom fabricated? Was it installed via a 337 for glider towing
or banner towing only? (There are no STC for tow hooks on Pawnees
AFAIK so it would have been a 337).

Especially if others are flying with a similar setups we need to try
hard to help prevent another tow release accident. Maybe this is
something the SSA could followup on with the NTSB folks involved. Its
a tragedy that the tow pilot was killed, and I'd hate to see something
missed even if there are other impairment factors here.

When aerotowing I get towed mostly behind Pawnees that have
retractable tow ropes and rope guillotines. That big handle is going
to work if needed. The soaring community is dependent on towplanes and
all our great tow pilots who support us and its very sad to see
accidents like this happening.

Darryl

On Jan 27, 6:56*am, Andy wrote:
On Jan 27, 2:03*am, bumper wrote:





From the NTSB report,

"Examination of the tow airplane tail hook assembly revealed that the
mounting plate was bent upward and the
heads of two connecting bolts were in contact with the base of the
rudder. The tail hook was intact and remained attached to the mounting
plate. The hook was in the locked position, closed around the tow
ring. The release cable remained attached to the hook and was
continuous to the cockpit release handle. Functional testing of the
tail hook assembly revealed no anomalies, and the assembly functioned
appropriately."

I'm really surprised at the above part of the NTSB report - - my take
is a bit different. I visited the yard where the wreckage was stored,
some weeks after the accident, as I happened to be there on other
business. I was not allowed to take pictures but did examine the
wreckage and in particular, the tow hook assembly. I'm not an expert
on aviation wreckage examination, I am trained in auto accident
investigation.

There were two Schweizer tow hooks mounted to a flat plate, with an
additional mounting hole for a third hook, all side-by-side ( I
understand multiple tow hooks are sometimes used for banner towing.)
The multiple hook mounting plate was attached to the aircraft via what
looked to be an alluminum bar, guessing 1/4" thick by 1.5" wide and
extending back maybe 8" from the rudder post spring mount . . . you
would be correct if you concluded this bar offered minimal resistance
to vertical loads without bending. As the NTSB says, the bar was bent
upwards and had impacted the lower part of the rudder, deforming
bending the bottom bow of the rudder up in the process. Though this
jammed the rudder, given the low altitude and nose down attitude pre-
crash, the jammed rudder probably was not causal.

The upward bend and position of the tow hooks inserted a significant
amout of slack in the tow release cable forward of the hook. This
slack, along with the new geometry or position of the tow hook with
respect to the release cable (i.e. now would be pulling upward on the
release toggle instead of forward as necessary to release the hook),
looked to me like it would have been impossible to release the tow
hook/s from the cockpit, even with no load on the hook. Otherwise the
hook appeared to be functional, just not by the cable (note that I did
not touch or try to operate the hook by hand - - I was only allowed to
look, not touch).

From what I saw, I believe the tow hook installation was inadequate
and unsafe. If it was causative, it was doubtless not the only cause
of this accident, though. It may well be that even if the mount had
been designed with the cutomary strength common in tow planes (rather
than just being adequate for banner towing) that a kiting glider would
still have resulted in the same tragic outcome.

I'm posting this as I think the NTSB overlooked and/or glossed over
the role the bent tow hook mount may have played, and in doing so
missed an opportunity for us to learn from this. As we know even a
properly installed upright Schweizer hook can be difficult to release
with upward loading. If the mount is inadequate (that aluminum bar
comes to mind) and bends up easily, unless the Bowden cable is
installed in such a way that the cable stays in line with the hook
(i.e. perpendicular to the release toggle) *and, unless there's a way
for the release lever or mechanism in the cockpit to take up any extra
slack that my be induced by the bent mount, I'd say there's no hope of
releasing whatsoever - - even if the tuggie is right on it.

bumper

Amazing the NTSB overlooked the tow hook installation and completely
disregarded the most likely probable cause - that the tug had an
unrecoverable upset caused *the glider being out of position.

This report, and one for a tow fatal at Peoria, AZ, seem to show that
NTSB is completely unfamiliar with the tug upset scenario.

The combination of a 2-33 which requires considerable forward stick
pressure to maintain position on tow, a distracted glider pilot, and a
****ty tug tow hook *was a sure set up for another dead tow pilot.

Andy- Hide quoted text -

- Show quoted text -

I am actually not surprised. The NTSB is notorious for missing the
point and opportunities to learn lessons. All they need to find is
some alcohol or drug in the blood and balme it on it and they are
done. Just like in car accidents. Otherwsie they conclude a pilot
error due to loss of control. I bet Bumper's investigation by just
looking at the tow hook was more thorough than the NTSB investigation.

Ramy

On Thu, 27 Jan 2011 15:38:19 -0800, Ramy wrote:

I am actually not surprised. The NTSB is notorious for missing the point
and opportunities to learn lessons. All they need to find is some
alcohol or drug in the blood and balme it on it and they are done. Just
like in car accidents. Otherwsie they conclude a pilot error due to loss
of control. I bet Bumper's investigation by just looking at the tow hook
was more thorough than the NTSB investigation.

Do you not have a govermental organisation like our AAIB in Leftpondia?

http://www.aaib.gov.uk/sites/aaib/publications/formal_reports.cfm

Their investigations and reports seem very thorough.

--
Alex

On Jan 27, 6:24*pm, Alex Potter wrote:
On Thu, 27 Jan 2011 15:38:19 -0800, Ramy wrote:
I am actually not surprised. The NTSB is notorious for missing the point
and opportunities to learn lessons. All they need to find is some
alcohol or drug in the blood and balme it on it and they are done. Just
like in car accidents. Otherwsie they conclude a pilot error due to loss
of control. I bet Bumper's investigation by just looking at the tow hook
was more thorough than the NTSB investigation.

Do you not have a govermental organisation like our AAIB in Leftpondia?

http://www.aaib.gov.uk/sites/aaib/publications/formal_reports.cfm

Their investigations and reports seem very thorough.

--
Alex

NTSB performs a similar function to AAIB but they are not only
responsible for air accidents, but all accidents in the national
transportation system, which includes road and rail. They seem to
investigate major accidents thoroughly. Their investigation staff may
be spread too thin to investigate accidents that don't have a
significant impact on public safety. Just speculation of course but it
does seem consistent with the standard of investigation that I have
seen for accidents that I knew something about before the report was
published.

Andy

On Jan 28, 6:55*am, Andy wrote:
On Jan 27, 6:24*pm, Alex Potter wrote:



On Thu, 27 Jan 2011 15:38:19 -0800, Ramy wrote:
I am actually not surprised. The NTSB is notorious for missing the point
and opportunities to learn lessons. All they need to find is some
alcohol or drug in the blood and balme it on it and they are done. Just
like in car accidents. Otherwsie they conclude a pilot error due to loss
of control. I bet Bumper's investigation by just looking at the tow hook
was more thorough than the NTSB investigation.

Do you not have a govermental organisation like our AAIB in Leftpondia?

http://www.aaib.gov.uk/sites/aaib/publications/formal_reports.cfm

Their investigations and reports seem very thorough.

--
Alex

NTSB performs a similar function to AAIB but they are not only
responsible for air accidents, but all accidents in the national
transportation system, which includes road and rail. *They seem to
investigate major accidents thoroughly. *Their investigation staff may
be spread too thin to investigate accidents that don't have *a
significant impact on public safety. Just speculation of course but it
does seem consistent with the standard of investigation that I have
seen for accidents that I knew something about before the report was
published.

Andy

This NTSB report is an embarrassment. How many stone cold sober tow
pilots could recover an upset at 200feet? I haven't flown a 150hp
Pawnee but I've heard it has trouble getting out of its own way in
benign circumstances much less a kiting glider at 200 feet and a
release system that may have been compromised.

On Fri, 28 Jan 2011 04:55:21 -0800, Andy wrote:

NTSB performs a similar function to AAIB but they are not only
responsible for air accidents, but all accidents in the national
transportation system, which includes road and rail. They seem to
investigate major accidents thoroughly. Their investigation staff may
be spread too thin to investigate accidents that don't have a
significant impact on public safety. Just speculation of course but it
does seem consistent with the standard of investigation that I have seen
for accidents that I knew something about before the report was
published.

In the UK, we split the functions between the RAIB, AAIB and the police,
for railways, aviation and road transport respectively.

Both of the AIBs publish extensively documented, detailed reports, after
thorough investigations. I've tried, and failed, to find similarly
detailed reports on the NTSB web site. Are there any?

--
Alex

On Jan 28, 10:58*am, 150flivver wrote:
*How many stone cold sober tow
pilots could recover an upset at 200feet? *

My guess is none. You have to recognise the problem, find the release
handle which is poorly placed in all the Pawnees I have flown, pull
it, hope the hook load is not so high that the rope can't be dumped,
and then recover from the dive.

Andy