On Thursday, June 20, 2013 6:38:01 PM UTC-6, Ramy wrote:
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

I thing the NTSB report gives a lot of information and a pretty clear description of what happened.

The proper recovery from a ground launch failure is to pitch over at zero G until the nose is as far below the horizon as it was above at the point of failure then recover from the dive to a normal glide at 1.5xVs. Zero G eliminates induced drag so the glider retains more airspeed. Height loss from a rope break is determined by the minimum airspeed at the top of the ballistic trajectory. This airspeed may be below the 1G level flight stall speed but the glider remains unstalled at 0G.

From the NTSB report:

"Other witnesses located adjacent to the departure runway reported that the first stage of the automobile ground 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 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."

If this witness is to be believed, the launch failed at a steep nose-up attitude followed by a continued climb ending level flight attitude. This indicates no attempt at airspeed recovery. A turn was then initiated from what was likely a critically low airspeed resulting in a spin to impact.