Glider accident while filming commercial in 2011. NTSB Report updated

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.

On Thursday, June 20, 2013 3:53:31 PM UTC-4, 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.

A Flugbeugzau DG 1000... If they can't get hte manufacturer right... I wanted to stop reading right there...

Sad event.

The most telling statement seems to be the very last line of the report.

"The tow rope broke during the initial takeoff..."

I take this statement at face value. The rope BROKE. It didn't otherwise inadvertently release such as a back release, the release was mistakenly pulled or failed, etc.

Never having done an auto or winch tow, is it unrecoverable if the rope would separate from the glider at 200ft when at a "steep nose-high attitude"?

- John

It is recoverable with a quick lowering of the nose and, most likely,
landing straight ahead or to one side or another.


"JohnDeRosa" wrote in message
...
Sad event.

The most telling statement seems to be the very last line of the report.

"The tow rope broke during the initial takeoff..."

I take this statement at face value. The rope BROKE. It didn't otherwise
inadvertently release such as a back release, the release was mistakenly
pulled or failed, etc.

Never having done an auto or winch tow, is it unrecoverable if the rope
would separate from the glider at 200ft when at a "steep nose-high
attitude"?

- John

On Thursday, June 20, 2013 3:25:18 PM UTC-6, JohnDeRosa wrote:
Sad event.



The most telling statement seems to be the very last line of the report.



"The tow rope broke during the initial takeoff..."



I take this statement at face value. The rope BROKE. It didn't otherwise inadvertently release such as a back release, the release was mistakenly pulled or failed, etc.



Never having done an auto or winch tow, is it unrecoverable if the rope would separate from the glider at 200ft when at a "steep nose-high attitude"?



- John

The answer also depends on airspeed and how quickly the pilot initiates a recovery.

There's an envelope from within which a safe recovery is possible. I call it the "AAA envelope" bounded Altitude, Airspeed and Attitude. With enough airspeed and altitude, you can recover from anything. A steep nose-up attitude at low altitude and airspeed can be unrecoverable.

This can actually be computed using physics simulators like Matlab. For example, from the initiation of recovery, an ASK-21 at 60kts, which is a typical winch airspeed, and 45 degrees nose-up can recover to a normal glide at 1.3xVs with no loss of height assuming a well trained pilot using an aggressive recovery technique. OTOH, an ASK-21 at 50 knots and 50 degrees nose-up will lose 65 - 75 feet so you need to be higher than that. Common sense says you need to add a 100% safety margin on top of this.

Winch launch training involves a lot of these recoveries. A pilot on ground launch should be trained to expect a launch failure on every launch at any altitude and be prepared to deal with it safely.

Continuing the scenario a bit, there's obviously a point defined by height and distance remaining where landing ahead on the runway is no longer possible. If you're too close to the end to land and and too low to circle back, you're in what's been called the "end trap". Auto towing with a short tow rope it's easy to get "end trapped" which I suspect in this accident. With winch launch, you reach a height where a short pattern is possible before the land-ahead option is lost.

There are a bunch of troubling things in this report. I have a lot of ground launch (auto tow) time, but it's a bit dated, so maybe I've forgotten. IIRC, our target speeds were on the order of 50MPH or 55MPH in zero wind, not 70. This was with a Grob and 2-33, but I can't imagine that 70 is right. The flight profile also sounds odd, as if the pilot was hoping to do an extreme pull-up after building up rather than the usual transition from initial climb to the 45 degrees or so of stage 2 climb. Adding up these two, it seems easy to see how the rope may have been overstressed.

Finally, it's hard to tell, but it sounds like this wasn't a failed recovery from an extreme nose up low altitude rope break. From the text, it appears that it may have been a stall-spin after the initial recovery - maybe trying to perform a full 180 from low altitude? At least, that's how I read it.

Anyone else getting the same picture?

P3

On Thursday, June 20, 2013 7:33:12 PM UTC-4, Bill D wrote:
On Thursday, June 20, 2013 3:25:18 PM UTC-6, JohnDeRosa wrote:

Sad event.







The most telling statement seems to be the very last line of the report..







"The tow rope broke during the initial takeoff..."







I take this statement at face value. The rope BROKE. It didn't otherwise inadvertently release such as a back release, the release was mistakenly pulled or failed, etc.







Never having done an auto or winch tow, is it unrecoverable if the rope would separate from the glider at 200ft when at a "steep nose-high attitude"?







- John



The answer also depends on airspeed and how quickly the pilot initiates a recovery.



There's an envelope from within which a safe recovery is possible. I call it the "AAA envelope" bounded Altitude, Airspeed and Attitude. With enough airspeed and altitude, you can recover from anything. A steep nose-up attitude at low altitude and airspeed can be unrecoverable.



This can actually be computed using physics simulators like Matlab. For example, from the initiation of recovery, an ASK-21 at 60kts, which is a typical winch airspeed, and 45 degrees nose-up can recover to a normal glide at 1.3xVs with no loss of height assuming a well trained pilot using an aggressive recovery technique. OTOH, an ASK-21 at 50 knots and 50 degrees nose-up will lose 65 - 75 feet so you need to be higher than that. Common sense says you need to add a 100% safety margin on top of this.



Winch launch training involves a lot of these recoveries. A pilot on ground launch should be trained to expect a launch failure on every launch at any altitude and be prepared to deal with it safely.



Continuing the scenario a bit, there's obviously a point defined by height and distance remaining where landing ahead on the runway is no longer possible. If you're too close to the end to land and and too low to circle back, you're in what's been called the "end trap". Auto towing with a short tow rope it's easy to get "end trapped" which I suspect in this accident. With winch launch, you reach a height where a short pattern is possible before the land-ahead option is lost.

There are a bunch of troubling things in this report. I have a lot of ground launch (auto tow) time, but it's a bit dated, so maybe I've forgotten. IIRC, our target speeds were on the order of 50MPH or 55MPH in zero wind, not 70. This was with a Grob and 2-33, but I can't imagine that 70 is right.

---------------------------

From the DG1000 flight manual:
"Recommended winch launch airspeed 110-130 km/h (60-70 kts.)."

Theoretically, the best airspeed for winch launch is that which give the angle of attack for best L/D. With the extra wing loading due to the rope pull, it would certainly be in the 60 - 70 knot range.

On Thursday, June 20, 2013 4:55:19 PM UTC-7, Papa3 wrote:
There are a bunch of troubling things in this report. I have a lot of ground launch (auto tow) time, but it's a bit dated, so maybe I've forgotten. IIRC, our target speeds were on the order of 50MPH or 55MPH in zero wind, not 70. This was with a Grob and 2-33, but I can't imagine that 70 is right. The flight profile also sounds odd, as if the pilot was hoping to do an extreme pull-up after building up rather than the usual transition from initial climb to the 45 degrees or so of stage 2 climb. Adding up these two, it seems easy to see how the rope may have been overstressed.



Finally, it's hard to tell, but it sounds like this wasn't a failed recovery from an extreme nose up low altitude rope break. From the text, it appears that it may have been a stall-spin after the initial recovery - maybe trying to perform a full 180 from low altitude? At least, that's how I read it.



Anyone else getting the same picture?



P3



On Thursday, June 20, 2013 7:33:12 PM UTC-4, Bill D wrote:

On Thursday, June 20, 2013 3:25:18 PM UTC-6, JohnDeRosa wrote:



Sad event.















The most telling statement seems to be the very last line of the report.

On Thursday, June 20, 2013 4:55:19 PM UTC-7, Papa3 wrote:
Finally, it's hard to tell, but it sounds like this wasn't a failed recovery from an extreme nose up low altitude rope break. From the text, it appears that it may have been a stall-spin after the initial recovery - maybe trying to perform a full 180 from low altitude? At least, that's how I read it.

Anyone else getting the same picture?


This happened in my area and I was marginally involved in the aftermath (mostly second-hand, so apply some grains of salt as-necessary). Some things to keep in mind, regarding this accident:

1] It was done during the filming of a commercial, NOT a normal launch. There were goals to capture certain maneuvers and angles on-camera.
(You can provide your own conjecture about how that may or may not have affected people's thinking, actions, and/or safety-margins.)

2] The filming location was not chosen for its safety, it was chosen for its aesthetic appeal and/or possibly other factors (that I was not privy to). What I can say for a fact is that several other airports exist in the region that have much longer & wider runways, fewer obstructions, more taxiways, and more "outs" in case of an emergency. (And at least one person told me they suggested one of those other airports to the accident-pilot, sometime in the days or weeks before the accident).

4] Eyewitness reports by fellow pilots (to me) corroborate the NTSB report about the glider returning to "level" after the rope-break, prior to entering a turn/spin. You may speculate about whether the nose-down pitch recovery was done properly; or perhaps whether the pilot recovered properly but then got distracted looking at his emergency landing options. Or perhaps he lost track of the tow-vehicle and was afraid to pitch down and land on the runway area for fear of hitting the car/camera-crew. Or perhaps he had a plan but some combination of low-airspeed and/or cross-wind and/or wind-gradient and/or turbulence from the nearby trees resulted in a loss of lift on one or both wings.

Just remember its speculation. Speculating can be valuable to help us think through potential hazards and guard against them in our own experiences; and I think its worthwhile to play "what if" with accidents with a view towards making ourselves safer. Certainly lessons can be learned. But always keep in mind that we don't _know_ what was going on in that person's mind, or what aggravating factors might have tipped the situation out of "potentially unsafe" territory and into an "accident".

--Noel

On Thursday, June 20, 2013 5:16:45 PM UTC-7, noel.wade wrote:
On Thursday, June 20, 2013 4:55:19 PM UTC-7, Papa3 wrote:

Finally, it's hard to tell, but it sounds like this wasn't a failed recovery from an extreme nose up low altitude rope break. From the text, it appears that it may have been a stall-spin after the initial recovery - maybe trying to perform a full 180 from low altitude? At least, that's how I read it.



Anyone else getting the same picture?





This happened in my area and I was marginally involved in the aftermath (mostly second-hand, so apply some grains of salt as-necessary). Some things to keep in mind, regarding this accident:



1] It was done during the filming of a commercial, NOT a normal launch. There were goals to capture certain maneuvers and angles on-camera.

(You can provide your own conjecture about how that may or may not have affected people's thinking, actions, and/or safety-margins.)



2] The filming location was not chosen for its safety, it was chosen for its aesthetic appeal and/or possibly other factors (that I was not privy to). What I can say for a fact is that several other airports exist in the region that have much longer & wider runways, fewer obstructions, more taxiways, and more "outs" in case of an emergency. (And at least one person told me they suggested one of those other airports to the accident-pilot, sometime in the days or weeks before the accident).



4] Eyewitness reports by fellow pilots (to me) corroborate the NTSB report about the glider returning to "level" after the rope-break, prior to entering a turn/spin. You may speculate about whether the nose-down pitch recovery was done properly; or perhaps whether the pilot recovered properly but then got distracted looking at his emergency landing options. Or perhaps he lost track of the tow-vehicle and was afraid to pitch down and land on the runway area for fear of hitting the car/camera-crew. Or perhaps he had a plan but some combination of low-airspeed and/or cross-wind and/or wind-gradient and/or turbulence from the nearby trees resulted in a loss of lift on one or both wings.



Just remember its speculation. Speculating can be valuable to help us think through potential hazards and guard against them in our own experiences; and I think its worthwhile to play "what if" with accidents with a view towards making ourselves safer. Certainly lessons can be learned. But always keep in mind that we don't _know_ what was going on in that person's mind, or what aggravating factors might have tipped the situation out of "potentially unsafe" territory and into an "accident".



--Noel

Well said Noel.
So much for the "wait for the NTSB report" I keep hearing after every accident. After 2 years the NTSB report didnt tell us anything new. Since there may be new readers on RAS which did not read about this accident, discussing it further can only help.

Ramy