Cle Elum crash on NTSB

http://www.ntsb.gov/aviationquery/br...13X31821&key=1

NTSB Identification: WPR12FA010
14 CFR Part 91: General Aviation
Accident occurred Thursday, October 13, 2011 in Cle Elum, WA
Aircraft: DG FLUGZEUGBAU GMBH DG 1000S, registration: 7760A
Injuries: 1 Fatal.

This is preliminary information, subject to change, and may contain
errors. Any errors in this report will be corrected when the final
report has been completed.

On October 13, 2011, about 1558 Pacific daylight time, a Flugzeugbau
DG 1000 S glider, N7760A, impacted terrain while being ground launched
from a tow vehicle at Cle Elum Municipal Airport (S93), Cle Elum,
Washington. The commercial pilot, the sole occupant, was fatally
injured and the 2-seat glider sustained substantial damage. The glider
was registered to Northwest Eagle Soaring LLC, and operated under the
provisions of Title 14 Code of Federal Regulations Part 91. Visual
meteorological conditions prevailed and no flight plan had been filed.

The NTSB investigator-in-charge and law enforcement officials
interviewed multiple witnesses located adjacent to the departure
runway. The witnesses reported that the first stage of auto-tow launch
appeared normal, and the glider became airborne within the first one-
third of the runway. Shortly thereafter, about three-quarters of the
way down the asphalt runway, the glider pitched to a steep nose-high
attitude. As the glider ascended through about 100 – 125 feet above
the ground, the rope slackened. The glider continued to ascend, and
then leveled off about 200 feet above the end of the runway. Shortly
after, the glider entered a steep right bank and descended into the
ground. As it descended, the glider turned approximately 300 degrees
from its initial departure heading before it impacted terrain.

A full-size sport utility vehicle was towing the glider. The nylon tow
rope used measured approximately 234 feet and was 5/16-inch in
diameter.

Runway 07/25 is 2,552 feet in length and 40 feet wide. The runway is
bordered to the north by large conifer trees.

I'm not entirely sure what to make of the whole thing, but if that
report is correct the basic facts that emerged previously are
confirmed:

* Auto tow with SUV
* Tow rope of 230-foot length
* Tow rope of 5/16" nylon
* Runway length of 2500 feet
* Glider achieved a max alt of 200 feet near the departure end of
runway
* Glider appeared to initiate a right spin near the departure end of
runway

That still leaves in question what they were trying to accomplish, and
how.

Bob K.

On Oct 26, 4:10*pm, Bob Kuykendall wrote:
I'm not entirely sure what to make of the whole thing, but if that
report is correct the basic facts that emerged previously are
confirmed:

* Auto tow with SUV
* Tow rope of 230-foot length
* Tow rope of 5/16" nylon
* Runway length of 2500 feet
* Glider achieved a max alt of 200 feet near the departure end of
runway
* Glider appeared to initiate a right spin near the departure end of
runway

That still leaves in question what they were trying to accomplish, and
how.

Bob K.

Unfortunately, no mention of the speed obtained by the SUV. Maybe
that will come out in the follow-on reports..

Bob Kuykendall wrote:
I'm not entirely sure what to make of the whole thing, but if that
report is correct the basic facts that emerged previously are
confirmed:

* Auto tow with SUV
* Tow rope of 230-foot length
* Tow rope of 5/16" nylon
* Runway length of 2500 feet
* Glider achieved a max alt of 200 feet near the departure end of
runway
* Glider appeared to initiate a right spin near the departure end of
runway

That still leaves in question what they were trying to accomplish, and
how.

Bob K.

The main question, as Bob said, was not answered. What was their
intention? If it was to land straight ahead, than why did he stay on
tow so long and pulled up at the end? Or perhaps the intention was to
land in a field past the end of the runway? There is mention of trees
at the north side of the runway but no mention of what was ahead.
However if the intention was to do a 180 and land then he was pretty
much doomed before he left the ground as Gary said. Unfortunately it
will probably take a year until we get these answers from the NTSB
final report, IF they will address it. But there are likely people who
read this and know the answers but will rather not share it.

Ramy

What else about their “intentions” were you hoping the NTSB would
state in a preliminary accident report? Were you expecting them to
detail the entire planned flight path, launch sequence, acceleration
rate, tow car speed for the climb, film crew briefings? Not gonna
happen with with the NTSB. They provided some eye-witness information
which may or may not be misleading, and some facts about the airport,
the registered owner of the plane, etc. We have been told what their
intentions were. We have been told they were filming a commercial
for Cadillac. We have been told they used the vehicle for the ground
launch. We have been told they planned to tow the DG up with their
rope (which the NTSB reports as 234 feet long, made from 5/16th
nylon. Although, I suspect it is polypropylene.), do a 180, and land
back the other direction. As for the rest of the sequence, I was not
there, but am presenting what I believe is a plausible explanation of
how the events may have transpired.

We can assume that the rope was intact after the launch, as the NTSB
report reports the length of the rope, and makes no comments about it
being broken, or rings found in the glider, etc. They would have
stated the rope was broken it if had been. So, this does not appear
to be any sort of rope overload, as some were presuming.

The witnesses stated that the takeoff appeared normal. There is
enough confusing information after this if you start putting the math
to it about distance down the runway, altitude, etc to make one
suspicious of the distance and height observations. The witnesses
reported that the plane "pitched to a steep nose high attitude." We
know that at some point in the climb (estimated to be 100 to 125
feet), the rope “slackend”. Three ways the rope can "slacken". Tow
vehicle slows down, glider pushes over, or rope disconnects. They say
the glider continued to ascend to about 200 feet of altitude and
leveled off. Based on what they say happened next, I believe the rope
disconnected and the pilot pushed over.

In an auto tow launch, you lift off, bring the nose up a little, get
some altitude, then bring the nose on up. As you near the top of the
climb, the nose comes back down to pretty close to level. Watch any
video of a winch launch on YouTube. Very similar, but on car tow, you
don't accelerate as rapidly. Depending on how the launch is
conducted, you will be rotating to full climb between 100 and 200
feet. Unfortunately, if you try for the same profile with a 234 foot
rope as you would with a 2000 foot rope (be rotating to full climb
angle at 100 feet AGL), the rope to hitch angle will likely hit the
"back release" angle at somewhere between 100 and 150 feet AGL. So,
if you try to fly a "normal" launch profile on a short rope, you will
likely get a low altitude back release, as the pilot in this accident
probably got.

So, here you are, about 100 to 150 or so feet AGL, 35-40 degrees or so
nose up, about right on speed for the climb, and the release does its
backrelease thing. You are surprised, but put the stick on the
forward stop as you are trained. The plane keeps going up and keeps
slowing down as you are going over the top. By the time you go over
the top at about 200 feet or so, and have the nose back down to normal
gliding attitude, your airspeed is pretty well gone. Do the math to
see how much altitude you will gain in slowing from 60 to 30 knots or
so, no drag losses. Unless you keep the stick forward to get the nose
well below the normal gliding attitude to get flying speed back (and
give up what precious little altitude you have), you will stall.
Pilot probably came across the top at about two hundred or so feet
after this, less than one g and slower than 1 g stall speed. He then
likely attempted to initiate the turn, as things were "back to normal,
per the plan." Meaning, he was near the far end of the runway, at
about 200 feet, ready to turn around. Trouble is, he was below stall
speed. Attempted to turn and entered a spin.

As to the max speed the towcar attained, I would be very surprised if
they were attempting other than a "normal" ground launch sequnce, but
with a very short rope. "Normal" being accelerate the car to flying
speed for the plane plus safety margin (no wind, say 65 MPH or so for
the DG? Remember, his airspeed would go up as soon as he starts to
climb, and the intention was to climb), hold that speed, drive to near
the end, and stop.

A very sad and tragic accident.

Respectfully,
Steve Leonard

My condolences go out to the family and friends of the pilot.

I have no opinion on the accident as I don't have all the facts and
I'm no expert flight dynamicist.

However, given what I've read on here over the last few days,
some of you, particularly the pilots with no winch launch
experience, will find the BGA winch launch safety initiative
informative:

http://www.gliding.co.uk/bgainfo/saf...hlaunching.htm

My condolences go out to the family and friends of the pilot.

I have no opinion on the accident as I don't have all the facts and
I'm no expert flight dynamicist.

However, given what I've read on here over the last few days,
some of you, particularly the pilots with no winch launch
experience, will find the BGA winch launch safety initiative
informative:

http://www.gliding.co.uk/bgainfo/saf...hlaunching.htm

At 10:49 28 October 2011, Paul Tribe wrote:
My condolences go out to the family and friends of the pilot.

I have no opinion on the accident as I don't have all the facts and
I'm no expert flight dynamicist.

However, given what I've read on here over the last few days,
some of you, particularly the pilots with no winch launch
experience, will find the BGA winch launch safety initiative
informative:

http://www.gliding.co.uk/bgainfo/saf...hlaunching.htm





Huh? - I definitely only clicked the "post" button once (via
gliderpilot.net).

Let's see what happens to this message.

On Oct 28, 3:49*am, Paul Tribe wrote:
My condolences go out to the family and friends of the pilot.

I have no opinion on the accident as I don't have all the facts and
I'm no expert flight dynamicist.

However, given what I've read on here over the last few days,
some of you, particularly the pilots with no winch launch
experience, will find the BGA winch launch safety initiative
informative:

http://www.gliding.co.uk/bgainfo/saf...hlaunching.htm

Looking at the Google Earth image of the airport, there are fields at
both east and west ends, although the west one is a bit small. At 200
feet altitude with only 600 feet of runway in front of you and,
presumably, an SUV sitting in the middle of it, landing ahead seems to
be ruled out. This leaves landing in the small field ahead or a 180
to land back on the asphalt. Neither option looks really wonderful,
but it's increasingly looking as if the pilot opted for the turn.

Mike

On Oct 27, 9:28*pm, Steve Leonard wrote:
What else about their “intentions” were you hoping the NTSB would
state in a preliminary accident report? *Were you expecting them to
detail the entire planned flight path, launch sequence, acceleration
rate, tow car speed for the climb, film crew briefings? *Not gonna
happen with with the NTSB. *They provided some eye-witness information
which may or may not be misleading, and some facts about the airport,
the registered owner of the plane, etc. *We have been told what their
intentions were. * We have been told they were filming a commercial
for Cadillac. *We have been told they used the vehicle for the ground
launch. *We have been told they planned to tow the DG up with their
rope (which the NTSB reports as 234 feet long, made from 5/16th
nylon. *Although, I suspect it is polypropylene.), do a 180, and land
back the other direction. *As for the rest of the sequence, I was not
there, but am presenting what I believe is a plausible explanation of
how the events may have transpired.

We can assume that the rope was intact after the launch, as the NTSB
report reports the length of the rope, and makes no comments about it
being broken, or rings found in the glider, etc. *They would have
stated the rope was broken it if had been. *So, this does not appear
to be any sort of rope overload, as some were presuming.

The witnesses stated that the takeoff appeared normal. *There is
enough confusing information after this if you start putting the math
to it about distance down the runway, altitude, etc to make one
suspicious of the distance and height observations. *The witnesses
reported that the plane "pitched to a steep nose high attitude." *We
know that at some point in the climb (estimated to be 100 to 125
feet), the rope “slackend”. *Three ways the rope can "slacken". *Tow
vehicle slows down, glider pushes over, or rope disconnects. *They say
the glider continued to ascend to about 200 feet of altitude and
leveled off. *Based on what they say happened next, I believe the rope
disconnected and the pilot pushed over.

In an auto tow launch, you lift off, bring the nose up *a little, get
some altitude, then bring the nose on up. *As you near the top of the
climb, the nose comes back down to pretty close to level. *Watch any
video of a winch launch on YouTube. *Very similar, but on car tow, you
don't accelerate as rapidly. *Depending on how the launch is
conducted, you will be rotating to full climb between 100 and 200
feet. *Unfortunately, if you try for the same profile with a 234 foot
rope as you would with a 2000 foot rope (be rotating to full climb
angle at 100 feet AGL), the rope to hitch angle will likely hit the
"back release" angle at somewhere between 100 and 150 feet AGL. *So,
if you try to fly a "normal" launch profile on a short rope, you will
likely get a low altitude back release, as the pilot in this accident
probably got.

So, here you are, about 100 to 150 or so feet AGL, 35-40 degrees or so
nose up, about right on speed for the climb, and the release does its
backrelease thing. *You are surprised, but put the stick on the
forward stop as you are trained. *The plane keeps going up and keeps
slowing down as you are going over the top. *By the time you go over
the top at about 200 feet or so, and have the nose back down to normal
gliding attitude, your airspeed is pretty well gone. *Do the math to
see how much altitude you will gain in slowing from 60 to 30 knots or
so, no drag losses. *Unless you keep the stick forward to get the nose
well below the normal gliding attitude to get flying speed back (and
give up what precious little altitude you have), you will stall.
Pilot probably came across the top at about two hundred or so feet
after this, less than one g and slower than 1 g stall speed. *He then
likely attempted to initiate the turn, as things were "back to normal,
per the plan." *Meaning, he was near the far end of the runway, at
about 200 feet, ready to turn around. *Trouble is, he was below stall
speed. *Attempted to turn and entered a spin.

As to the max speed the towcar attained, I would be very surprised if
they were attempting other than a "normal" ground launch sequnce, but
with a very short rope. *"Normal" being accelerate the car to flying
speed for the plane plus safety margin (no wind, say 65 MPH or so for
the DG? *Remember, his airspeed would go up as soon as he starts to
climb, and the intention was to climb), hold that speed, drive to near
the end, and stop.

A very sad and tragic accident.

Respectfully,
Steve Leonard


What else about their “intentions” were you hoping the NTSB would
state in a preliminary accident report?

This is precisely the problem with NTSB reports, they don't provide
enough facts to make any conclusion. The final report usually come a
year later and often does not have much more information than the
preliminary reports. So so much for the requests to "wait for the NTSB
report". We waited, and now we need the facts so we can draw our own
conclusions and learn the lessons.
And I am pretty sure that some of the readers know more.

As for the plan to do a 180 to land, there is no mention of it in the
NTSB report, only from Gary's comment. I think this is the key to be
able to categorize this accident as "something went terribly wrong" vs
"someone made a terrible decision" or did not know what they were
doing. There is no much we can do to prevent the "something went
terribly wrong" type of accidnets, but there is much we can do to
prevent the later and learn the lessons. Perhaps someone reading this
will, as a result, think twice before attempting an auto tow with a
short rope on a short runway with limited straight ahead options.
Incidentally, I recently visited such an airport were they attempted
an autolaunch on a short runway, slightly uphill with no straight
ahead option, and quickly learned they will be better off finding a
tow plane.

Ramy