http://ozreport.com/10.017#4

http://ozreport.com/10.018#2

http://ozreport.com/forum/viewtopic.php?t=1143&postdays=0&postorder=asc&start=0

http://ozreport.com/forum/viewtopic.php?t=1143&postdays=0&postorder=asc&start=145

Why do I consider the 300' tow rope the proximate cause of the accident?

Because if the rope had been 150' the pilot would be alive today.

Why? Because the conditions of his tow would have been much less severe and he would have either towed without incident or been able to release. Remember that my first reports reported on the conditions before I knew that the rope played a significant part in why those conditions felt so severe to me. It was only have I flew in similar conditions (and have so a few times since here) with the 150' rope that I saw clearly how much the length of the rope played in my perception of the severity of the conditions.

Why would the conditions of his tow have been much less severe? Because the tug and the pilot would have been much more likely to have been in the same air parcels at the same time and the dramatic differences in altitude between the tug and the pilot would not have been experienced by the pilot (as they were according to Chris Smith who watched the accident from the side) and by myself a few minutes before the accident.

But how did these differences in altitude contribute to the accident?

First, the glider was witnessed, again by Chris Smith, to be "out of whack," which I take to mean yawing and rolling behind the tug.

Second, the tug was seen to get far below the glider and the glider to approach the tug thereby putting a bow in the line at the same time the glider was yawing and rolling.

Third, dramatic differences in altitude between the tug and the glider would, I assume, cause significant stress for the pilot. They did for me (as I reported at the time), making it less likely for the pilot to be able to take the appropriate action when things went wrong.

Fourth, with the glider rolling and yawing behind the tub which was below it there became the possibility that the tow rope would contact the side wire, which it obviously did.

Fifth, with a 150' rope the chances that the rope would contact the side wire are dramatically reduced as the chance for a bow in the rope and the pilot overshooting the tow rope are greatly reduced. The rope must first be overshot then pulled tight (as the tug hits a new thermal or the glider heads off in the sideways direction) for this accident to occur. It is quite difficult to yaw and roll into this situation without the rope going slack first, which happens much more frequently with the 300' rope (and did to me and this pilot on this very day).

Sixth, with the Windtech release the pilot most likely would have had difficulty releasing with a rope that was not tight.

Would the pilot have lived if he had a different release? Perhaps. I certainly would argue for a different type of release. But we don't know if he tried to release. The slack rope combined with the Windtech release would have made it difficult to release.

Would the pilot have lived if conditions were calm, i.e. less thermic and less wind. Yes. He would also have lived if he hadn't towed that day. We have been towing in similar conditions since then.

Would the pilot have lived if he was more experieced? I don't know his level of aerotow expereince so I can't say.

Would the pilot have lived if the tug pilot was more experienced? Unclear if the tug pilot could have done anything to save the hang glider pilot. The tug pilot mentioned that in his mirror he could not see the pilot because the pilot was too far away, i.e. 300'.

Could the pilot have lived if he used a leader with a weak link on the end? Likely. After the end of the tow rope wrapped around the side wire the weaklink at the end of the leader could have easily broken before the tow rope and tug tucked the glider.

http://ozreport.com/forum/viewtopic.php?t=1143&postdays=0&postorder=asc&start=141

Now, as to the Windtech bridle and any part it may have played in the accident.

Did the pilot try to release before the line knotting itself around the sidewire and found himself unable to do so? We don't know, but if the release wouldn't function properly, this would have been a big problem.

The Windtech aerotow release is a "three ring" circle with the straps tied to your shoulder tabs and a short string to the "three ring" release. The issues with it are:

1. You have to take your hand off the base bar to grab the string.

2. The string is hard to find being thin, and next to the straps.

3. The three ring circle may not release with a pull on the string if there is no tension other than the weight of the rope on it. If the rope is bowed (which apparently was the case before the accident) then the release may not release.

We know from Zupy that the weaklink broke and that the pilot didn't successfully release.

I had argued with the pilot on the previous two days for him to change his bridle to a barrel release pro-tow system. Here are the characteristics of this system:

1. You do have to take your hand off the base bar.

2. The barrel is easy to find and always in the same spot and right next to the base bar.

3. The barrel release will release with only the weight of the line.

I have pictured many releases in the Oz Report, some of which will release with one hand with no line weight at all.

The only production release that I am aware of that doe not require that you remove your hand from the base bar is the one from Lookout:

http://www.hanglide.com/miva/merchant.mv?Screen=CTGY&Store_Code=LME&Category_Code=AE

Bill Moyes argues that you should never have to remove your hand from the base bar to release, but the Moyes release requires this unless the brake handle is on the base tube and even then it isn't as direct and quick to use as the Lookout release.

I believe that the barrel release when used with 150' spectra is a reasonably safe system. When used with 300' poly in rough conditions, not nearly as safe.

I spoke with Jim Prahl about the spectra line lengths used at Quest Air. The normal length for competition is 200'. Students are often towed with 220' ropes, but 200' is used also.