Glider accident while filming commercial in 2011. NTSB Report updated

No mention of the pilot's previous experience with winch / autotow
launching

KN

At 05:30 21 June 2013, wrote:
Le jeudi 20 juin 2013 21:53:31 UTC+2, Steve Leonard a =E9crit=A0:

http://www.ntsb.gov/aviationquery/br...13X31821&ntsb=
no=3DWPR12FA010&akey=3D1
=20
=20
=20
Happened to be looking through the NTSB Database and saw that they
update=
d the report about a month ago.

It looks like they tried to more or less duplicate an old commercial by
Mic=
helin, where you saw an ASK-21 being auto-towed on a frozen lake. The
glide=
r went brutally up on a very short rope and released almost immediately.
Th=
en the car came to a braking halt just in front of an obstacle, while the
g=
lider was flying away. It was to illustrate the grip of a "Drice" winter
ti=
re... I can't find it on the web anymore. Some small stills are visible
if
=
you google "Michelin Drice" for images, but the links are dead.

Sad event and scary stuff.

Can anyone comment if the "steep nose high attitude" was intentional? Were the previous launches straight line low hops which would seem to be safer? Low hops would keep both the glider and the (very important) automobile in the same camera frame. Could something have occurred in the cockpit which forced a dramatic change in pitch attitude?

Which, to me, points back to the length of the rope (234ft) and the tow car driver stating that "The pilot planned to become airborne and then circle back to the airport to land.". Really? Circle back using a 234ft launch rope? He would have only gotten, what, 100feet high? I would seriously doubt that this experienced of a glider pilot (CFIG) would have announced that he could "circle back" even if he thought he would get 200-300 ft sling shot like launch. If not then it flies in the face of what the driver said.

- John "Speculation" D.

I wish we could see the videos.

Boggs

On Friday, June 21, 2013 8:16:25 AM UTC-6, JohnDeRosa wrote:
Can anyone comment if the "steep nose high attitude" was intentional? Were the previous launches straight line low hops which would seem to be safer? Low hops would keep both the glider and the (very important) automobile in the same camera frame. Could something have occurred in the cockpit which forced a dramatic change in pitch attitude?



Which, to me, points back to the length of the rope (234ft) and the tow car driver stating that "The pilot planned to become airborne and then circle back to the airport to land.". Really? Circle back using a 234ft launch rope? He would have only gotten, what, 100feet high? I would seriously doubt that this experienced of a glider pilot (CFIG) would have announced that he could "circle back" even if he thought he would get 200-300 ft sling shot like launch. If not then it flies in the face of what the driver said.



- John "Speculation" D.

Cle Elum Runway 7/25
Dimensions: 2552 x 40 ft.

With a runway this short, a pilot would have to climb very steeply to get any height at all. I'll guess the Caddy towing a DG1000 would need at least 1000' to reach 70mph and another 500' or so to stop. Add 234' of rope length and that leaves less than 700' of runway for the glider to climb - maybe much less.

OTOH, runways this short are used for winch launch. You could expect at least 1000' AGL launches. But then, the Caddy wouldn't have a leading role.

Been doing this a long time. Not confused.

Maybe I need to work on my writing skills.


"Bill D" wrote in message
...
On Thursday, June 20, 2013 6:58:55 PM UTC-6, Dan Marotta wrote:
Max ground launch speed for my LAK-17a is 75 kias.

Don't confuse max ground launch speed (Vw)with recommended airspeed for
winch launch. The DG1000 Vw is 81 knots.

I just started reviewing your training guide, Bill, and I must say,
"Excellent!" It's time to go fly my glider but I've saved the links and
will review all of your stuff for this evening for the refresher benefit,
though I probably won't be doing another ground launch until next "weekend"
at Roach Dry Lake.

I learned to fly off a winch back in the late 80s at Alice Springs, NT,
Australia (Bond Springs, actually) in a Twin Lark with about a mile of
cable, IIRC. Very exciting stuff and we got away every time!

When Black Forest purchased a winch from the AF Academy, Joe Berger and I
removed the small-block Chevy engine and transmission, extended the frame,
and installed a big-block 454 from a truck donated by Dave Rolley. It was
great fun and we used it during the Women's Soaring Seminar at Westcliffe
back in '92 (I think it was - I'll have to dig out my t-shirt to be
sure...). We also used the winch in the test flying of the first PW-5 to
arrive in those parts. IIRC, the FAA required that all maneuvers intended
to be flown had to be done during the test flying and the owner, being a new
pilot asked Tom Serkowski and I to do the flying. What fun we had!

Unfortunately, there was very little support for the winch and it fell into
disrepair. I recently heard that it had been sold.


"Bill D" wrote in message
...
On Thursday, June 20, 2013 8:00:14 PM UTC-6, Papa3 wrote:
Disregard... looks like the whole setup was non-standard, so a lot of the
usual rules of thumb go out the door. I hadn't noticed the very short
rope for example...

With the increased interest in ground launch, I do think it's useful to
revisit some of the old rules of thumb that used to be well known.
Sure, we need the SOP and manuals (which are still out there), but it
seems to me that it's good to review the underlying physics every now
and then.



I would suggest reading George Moores papers on winch launch. George has
taken the whole subject of ground launch into the 21st century with a very
deep and detailed mathematical analysis. His fresh view of the subject is
very welcome. His papers can be read in the files section of the Yahoo
group winchengineer and winchdesign.

If you'd like to take a look at my training materials, they can be
downloaded as PDF's.

Winch pilot training guide:
https://dl.dropboxusercontent.com/u/...20Rev%2017.pdf

Winch training slide show:
https://dl.dropboxusercontent.com/u/...20Training.pdf

Airfield operations:
https://dl.dropboxusercontent.com/u/...operations.pdf

On Friday, June 21, 2013 9:49:00 AM UTC-6, Dan Marotta wrote:
I just started reviewing your training guide, Bill, and I must say,

"Excellent!"

Thanks for the kind word. My only objective is to promote safe winch launch.

I'm positive that if it's done right, winch launch is far safer than aero tow. Germans suffer one accident on average every 180,000 winch launches while we suffer one every 24,000 aero tows. I know there are cultural differences but, presumably, we're pretty good at aero tow and they're at least as good at winch launch so the comparison is probably valid.

It's natural for familiar things like aero tow to seem safe and unfamiliar things like winch launch to look unsafe but the numbers tell a different story.

On Thursday, June 20, 2013 1:53:31 PM UTC-6, Steve Leonard wrote:
http://www.ntsb.gov/aviationquery/br...FA010 &akey=1



Happened to be looking through the NTSB Database and saw that they updated the report about a month ago.

Some have said there's nothing new in this report. Indeed there remain some missing details, but there is also a new fact that I don't recall from the prior reports and my inquiries, including discussion with the observer in the back of the launch vehicle.

If the facts are correct, anyone involved in ground launching should have zeroed in on the rope. Nylon rope is very elastic compared to premium UHMWPE ropes, that is, nylon has some 16% elongation at 15% of breaking strength.. UHMWPE rope elongation at 30% of breaking strength is under 1%.

Working limits of premium UHMWPE and steel wire ropes are 1/5 to 1/6 of breaking strength. During winch launching we tend to operate beyond these working limits regularly by loading to 1/4 to 1/3 of breaking strength with premium UHMWPE ropes, and presumably as high as 3/5 with the regular UHMWPE and steel wire ropes. For all practical purposes, there is minimal elongation.

On Friday, June 21, 2013 7:16:25 AM UTC-7, JohnDeRosa wrote:
Can anyone comment if the "steep nose high attitude" was intentional?

I don't think anyone can say exactly what was intentional, other than the deceased pilot.

I have heard - secondhand - that during the planning of the commercial they had wanted a shot from in front of the SUV looking back at it, with the glider rising suddenly & dramatically above it. Whether that was part of the final plans or whether they were trying to film that scene at the time of the accident is anyone's guess.

Frank - One thing to remember is that we do not _know_ if the pilot initiated the turn, or if it merely appeared so as the first phase of spin entry (i.e. a wing-drop). It is entirely possible the pilot was intending to land straight ahead but experienced an asymmetric stall (again, could've been the cross-wind, or a gust, or mechanical turbulence, or lack of coordinated controls, or whatever - we just don't know). I also don't think the satellite photo/maps show clearly if there are bushes or a fence between the runway and the large field - it is possible the pilot had better information about that than we do.

--Noel