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TOW PLANE Accident



 
 
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  #101  
Old March 23rd 19, 01:59 PM posted to rec.aviation.soaring
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Default TOW PLANE Accident

On Thursday, March 21, 2019 at 10:54:25 AM UTC-4, Ernst wrote:
On Wednesday, March 20, 2019 at 11:24:28 AM UTC-5, Tango Eight wrote:

This an important discussion and I can agree with a lot of the statements being made.
But I also get the feeling that there is some resignation. These are preventable accidents as longs as there are no mechanical or pilot incapacitation issues.

In response to some of Evan’s statements:
The Skyline accident is an outlier.

Unfortunately, no.

Video evidence shows that the glider deck angle never gets out of normal limits.

Yes, but there was no recording when the glider got out of normal tow position, because the camera was off and the PIC got distracted checking on it and switching it on again.

It was not a kiting event.

You can quickly get out of normal tow position without “kiting”.

The fact is, these accidents are rare.

Unfortunately, no.

Here is a list of tow plane upset accidents from the NTSB database going back to 2000 (which I could find):

26 Apr 2002, PA 18-150, SGS 2-33, USAFA, Colorado Springs, CO (DEN02GA039)
[Please go to the docket and read the PIC’s written testimony.]

21 Aug 2011, Callair A-9B, SGS 2-33, Marshall, MI (CEN11LA585)
[Tragically, the PIC of the glider was killed in a crash with his Quickie Q200 two months later.]

6 Sep 2014, PA 25-235, SGS 2-33, Warner Springs, CA (WPR14LA367)

As with Walt’s incidents, there are certainly more tow plane upsets that are not ending in a disaster and are never reported. I am aware of a CA 150-150 being pulled nose down by a transition glider pilot with only few solo flights in a glider. The tow pilot could not release the Schweizer hook, the tow rope broke and the tow pilot was able to pull out with only a few hundred feet left.
It was also a SGS 2-33. While I agree that the 2-33 requires a lot of elevator push down on tow, this can’t be the root cause for such events. As with the two accidents discussed here, it happens with other gliders types as well.
The PIC of a glider in tow has to be able to stay consistently in the normal tow position. Flawlessly boxing the wake, not only on a quiet morning or evening, is a good indicator if you can handle abnormal tow positions. And no distractions from cameras, flight computers, passengers, canopy opening, objects falling down and so on, especially below 1,000 ft.

Ernst



Ernst, I agree with your comments, these accidents are preventable in the circumstances as you stated. I was well aware of the USAFA accident, I referenced this in a recent contentious discussion. I was astonished that the instructor, an Academy student and CFIG with "100 flights total" would think that with the tow plane directly below them and with a "taught" rope she could raise the nose slightly, slow up and allow him to recover his position. I HAVE NO WORDS. So much for the "brightest of the bright" as I was told they were while I was a member of the USAF.

I spent 10 years as a Nuclear Cardiovascular Technologist working closely with Cardiologists and have performed hundreds of Thallium stress tests. I had the opportunity recently to have breakfast with a retired cardiologist/friend, he read the autopsy record of the tow pilot in this case and said he would not be surprised that he might have had some sort of incapacitation in the seat as was noted in the report. As a private pilot he was surprised that someone with that cardiovascular history would have a medical certificate of any class. I can attest to the fact that having a glider KITE on you at a low altitude is a very shocking event and someone with a compromised cardiovascular system such as this individual might well become incapacitated even without evidence of a MI. This condition does not excuse the fact that this "instructor" failed to react properly and release immediately.

Your acknowledgement of the lack of video between the time the first video ended and the second one started is well taken but unfortunately the NTSB has only that to go on. I was impressed by the technical evaluation of the video that was available. Again, the idea that the tow pilot may have had an incapacitating event which my cardiologist friend said was "possible" (he thought a syncopal event was likely) from what he read does not excuse, here again another "instructor" looking away at a low altitude and failing to release immediately when he realized the position of the tow plane regardless of whose fault it might have been.

As I have previously noted I've experience two VERY SUDDEN kiting events, one at about 300-350 feet and one at 2000 feet. In the 300 foot event the student pilot failed to release when it should have been more than obvious to do so. I experienced the well known and documented condition (in big RED letters in the SSA/SSF documents) of the Schweizer release failure. The rope broke, I recovered at tree top level and the student managed to fly back to the runway. When I asked her what happened she was at a total loss for an answer. I've also had a commercial pilot add on student get seriously high on me at about 700 feet in a pattern tow, we hit a strong thermal and instead of staying in position with me he rode it up. I was not quite out of control but i did reach for the handle and look up into the mirror, all I could see was the bottom of his glider, no way he could have seen me. He should have released, he did not. It took several seconds for him to get the idea and descended and in doing so jerked me hard sideways producing a highly audible harmonic throughout the tow plane. I managed to maintain control, get him to the release point where he released. I landed and told his instrucor 'that was the worst tow I've ever experienced." He was obviously unaware of the requirement to release when he lost sight of the tow plane. I asked him to "tell me about that tow." He said he thought I was going to "fly up to him."

This and many other events (including my own glider training and I have nothing but the greatest respect and admiration for the two CFIGs from whom I learned to fly) makes me wonder if the process of telling a student to release when they lose sight of the tow plane is adequate. I remember being told "if we lose sight of the tow plane we release." I heard it a couple of times, it might have hit home more effectively if I had been told why? Althought some might intuitively understand why it is obvious to me that many do not. We practice rope breaks, why is there not some sort of practice for the loss of visual on the tow plane? (que the instructors who will say this is always part of their curriculum on every training flight) It could be incorporated into the rope brake training and I am NOT suggesting the instructor kite the glider on low tow to see what the student does, rather perhaps a startled voice at 500 feet yelling "you've just lost sight of the tow plane." If "instructors" aren't reacting quickly and appropriately, how can one expect students to do so?

I submit that every soaring event should include a reminder to the participants of this potential condition every day. When you lose sight of the tow plane...RELEASE. It should be the mantra over every glider operation.

I'm willing to bet that this might make a few CFIGs become more aware of this aspect of instruction. I'm additionally willing to bet that some will just dismiss my admonitions.

Any circumstance that might lead to the death of a tow pilot needs to be taken seriously. Any tow pilot who takes these circumstances lightly needs to rethink their position. Even with Tost releases or inverted Schweizer hooks and handles immediately available to the tow pilot in the upright, seated position, things can happen so fast that the end result will not be positive. If it's below 200 feet.....well I'm sure most of you can assume the outcome.

Fly safe my friends

Walt Connelly
FORMER Tow Pilot
7000 tows
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  #102  
Old March 23rd 19, 02:03 PM
Walt Connelly Walt Connelly is offline
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First recorded activity by AviationBanter: Aug 2010
Posts: 338
Default

Quote:
Originally Posted by Ernst View Post
On Wednesday, March 20, 2019 at 11:24:28 AM UTC-5, Tango Eight wrote:

This an important discussion and I can agree with a lot of the statements being made.
But I also get the feeling that there is some resignation. These are preventable accidents as longs as there are no mechanical or pilot incapacitation issues.

In response to some of Evan’s statements:
The Skyline accident is an outlier.

Unfortunately, no.

Video evidence shows that the glider deck angle never gets out of normal limits.

Yes, but there was no recording when the glider got out of normal tow position, because the camera was off and the PIC got distracted checking on it and switching it on again.

It was not a kiting event.

You can quickly get out of normal tow position without “kiting”.

The fact is, these accidents are rare.

Unfortunately, no.

Here is a list of tow plane upset accidents from the NTSB database going back to 2000 (which I could find):

26 Apr 2002, PA 18-150, SGS 2-33, USAFA, Colorado Springs, CO (DEN02GA039)
[Please go to the docket and read the PIC’s written testimony.]

21 Aug 2011, Callair A-9B, SGS 2-33, Marshall, MI (CEN11LA585)
[Tragically, the PIC of the glider was killed in a crash with his Quickie Q200 two months later.]

6 Sep 2014, PA 25-235, SGS 2-33, Warner Springs, CA (WPR14LA367)

As with Walt’s incidents, there are certainly more tow plane upsets that are not ending in a disaster and are never reported. I am aware of a CA 150-150 being pulled nose down by a transition glider pilot with only few solo flights in a glider. The tow pilot could not release the Schweizer hook, the tow rope broke and the tow pilot was able to pull out with only a few hundred feet left.
It was also a SGS 2-33. While I agree that the 2-33 requires a lot of elevator push down on tow, this can’t be the root cause for such events. As with the two accidents discussed here, it happens with other gliders types as well.
The PIC of a glider in tow has to be able to stay consistently in the normal tow position. Flawlessly boxing the wake, not only on a quiet morning or evening, is a good indicator if you can handle abnormal tow positions. And no distractions from cameras, flight computers, passengers, canopy opening, objects falling down and so on, especially below 1,000 ft.

Ernst

Ernst, I agree with your comments, these accidents are preventable in the circumstances as you stated. I was well aware of the USAFA accident, I referenced this in a recent contentious discussion. I was astonished that the instructor, an Academy student and CFIG with "100 flights total" would think that with the tow plane directly below them and with a "taught" rope she could raise the nose slightly, slow up and allow him to recover his position. I HAVE NO WORDS. So much for the "brightest of the bright" as I was told they were while I was a member of the USAF.

I spent 10 years as a Nuclear Cardiovascular Technologist working closely with Cardiologists and have performed hundreds of Thallium stress tests. I had the opportunity recently to have breakfast with a retired cardiologist/friend, he read the autopsy record of the tow pilot in this case and said he would not be surprised that he might have had some sort of incapacitation in the seat as was noted in the report. As a private pilot he was surprised that someone with that cardiovascular history would have a medical certificate of any class. I can attest to the fact that having a glider KITE on you at a low altitude is a very shocking event and someone with a compromised cardiovascular system such as this individual might well become incapacitated even without evidence of a MI. This condition does not excuse the fact that this "instructor" failed to react properly and release immediately.

Your acknowledgement of the lack of video between the time the first video ended and the second one started is well taken but unfortunately the NTSB has only that to go on. I was impressed by the technical evaluation of the video that was available. Again, the idea that the tow pilot may have had an incapacitating event which my cardiologist friend said was "possible" (he thought a syncopal event was likely) from what he read does not excuse, here again another "instructor" looking away at a low altitude and failing to release immediately when he realized the position of the tow plane regardless of whose fault it might have been.

As I have previously noted I've experience two VERY SUDDEN kiting events, one at about 300-350 feet and one at 2000 feet. In the 300 foot event the student pilot failed to release when it should have been more than obvious to do so. I experienced the well known and documented condition (in big RED letters in the SSA/SSF documents) of the Schweizer release failure. The rope broke, I recovered at tree top level and the student managed to fly back to the runway. When I asked her what happened she was at a total loss for an answer. I've also had a commercial pilot add on student get seriously high on me at about 700 feet in a pattern tow, we hit a strong thermal and instead of staying in position with me he rode it up. I was not quite out of control but i did reach for the handle and look up into the mirror, all I could see was the bottom of his glider, no way he could have seen me. He should have released, he did not. It took several seconds for him to get the idea and descended and in doing so jerked me hard sideways producing a highly audible harmonic throughout the tow plane. I managed to maintain control, get him to the release point where he released. I landed and told his instrucor 'that was the worst tow I've ever experienced." He was obviously unaware of the requirement to release when he lost sight of the tow plane. I asked him to "tell me about that tow." He said he thought I was going to "fly up to him."

This and many other events (including my own glider training and I have nothing but the greatest respect and admiration for the two CFIGs from whom I learned to fly) makes me wonder if the process of telling a student to release when they lose sight of the tow plane is adequate. I remember being told "if we lose sight of the tow plane we release." I heard it a couple of times, it might have hit home more effectively if I had been told why? Althought some might intuitively understand why it is obvious to me that many do not. We practice rope breaks, why is there not some sort of practice for the loss of visual on the tow plane? (que the instructors who will say this is always part of their curriculum on every training flight) It could be incorporated into the rope brake training and I am NOT suggesting the instructor kite the glider on low tow to see what the student does, rather perhaps a startled voice at 500 feet yelling "you've just lost sight of the tow plane." If "instructors" aren't reacting quickly and appropriately, how can one expect students to do so?

I submit that every soaring event should include a reminder to the participants of this potential condition every day. When you lose sight of the tow plane...RELEASE. It should be the mantra over every glider operation.

I'm willing to bet that this might make a few CFIGs become more aware of this aspect of instruction. I'm additionally willing to bet that some will just dismiss my admonitions.

Any circumstance that might lead to the death of a tow pilot needs to be taken seriously. Any tow pilot who takes these circumstances lightly needs to rethink their position. Even with Tost releases or inverted Schweizer hooks and handles immediately available to the tow pilot in the upright, seated position, things can happen so fast that the end result will not be positive. If it's below 200 feet.....well I'm sure most of you can assume the outcome.

Fly safe my friends

Walt Connelly
FORMER Tow Pilot
7000 tows
  #103  
Old March 23rd 19, 02:56 PM posted to rec.aviation.soaring
Dan Daly[_2_]
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Posts: 651
Default TOW PLANE Accident

The video pause is common on most Sports cameras. I have an EKEN H8, and in the manual it says "...The camera will record 10min. clips and overwrite the earliest clip when the microSD card is full." My previous camera recorded in 5 min clips (I guess the memory was smaller). It is annoying but can be stitched together afterwards. I imagine the cam processor is not big enough to record video to memory and write to the microSD card simultaneously, so it stops recording, writes to the card, wipes internal memory, then restarts recording. I'm told that the length of video clips is longer on cams like GoPro.
  #104  
Old March 24th 19, 07:51 AM posted to rec.aviation.soaring
John Foster
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Posts: 304
Default TOW PLANE Accident

On Saturday, March 23, 2019 at 8:56:54 AM UTC-6, Dan Daly wrote:
The video pause is common on most Sports cameras. I have an EKEN H8, and in the manual it says "...The camera will record 10min. clips and overwrite the earliest clip when the microSD card is full." My previous camera recorded in 5 min clips (I guess the memory was smaller). It is annoying but can be stitched together afterwards. I imagine the cam processor is not big enough to record video to memory and write to the microSD card simultaneously, so it stops recording, writes to the card, wipes internal memory, then restarts recording. I'm told that the length of video clips is longer on cams like GoPro.


My GoPro Hero 4 Silver records about 17min clips, but they do stitch together seamlessly, without any gaps. The camera does not stop recording unless the battery dies or the memory card fills up, which is different than what reportedly happened in this accident.
  #105  
Old March 24th 19, 04:16 PM posted to rec.aviation.soaring
Soarin Again[_2_]
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Posts: 30
Default TOW PLANE Accident

In regard to the 10/7/2017 low level tow plane crash/fatality, the final
NTSB report has now been published.

The report confirmed that the Pawnee had a Tost reel installed and
that the weak link had not failed as designed, rather the tow rope
itself broke. Additionally the report clarified that the tow planes
guillotine had not been activated and no weak link was recovered.

The NTSB metallurgist report states the following regarding the tow
rope, but no determination as to the rope mfg name or rope strength.

The received section of tow rope was visually and microscopically
examined in the NTSB Materials Laboratory.The as‐received rope was
separated at one end and intentionally cut at the other as show in
attached image 1711Image57402. The ¼ inch diameter rope had a
braided outer layer covering approximately 13 twisted inner strands.
Magnified inspection of the separation found mushroomed fiber ends
and partially fused strands indicative of adiabatic heating resulting
from high strain rate overstress separations of synthetic fiber ropes.
The longest strands were twisted as if they were part of a knot at the
time of separation. A dark band with a metallic sheen was visible on
the braided cover adjacent to the separation, see attached image
1711Image57407. A hand held x‐ray alloy analyzer revealed
significant amounts of aluminum in the darkest part of the band.

The docket did not include any line crew statements in regard to what
weak link may have been used for the tow.

A reasonable question for those World-Wide operations that use Tost
reels, would be. Is it uncommon for tow ropes to break, rather than
a prescribed weak link. If this was a rare anomaly, is there
some logical reason for it happening?

M Eiler


  #106  
Old March 24th 19, 11:05 PM posted to rec.aviation.soaring
NG[_2_]
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Posts: 30
Default TOW PLANE Accident

On Sunday, March 24, 2019 at 12:30:03 PM UTC-4, soarin wrote:
In regard to the 10/7/2017 low level tow plane crash/fatality, the final
NTSB report has now been published.

The report confirmed that the Pawnee had a Tost reel installed and
that the weak link had not failed as designed, rather the tow rope
itself broke. Additionally the report clarified that the tow planes
guillotine had not been activated and no weak link was recovered.

The NTSB metallurgist report states the following regarding the tow
rope, but no determination as to the rope mfg name or rope strength.

The received section of tow rope was visually and microscopically
examined in the NTSB Materials Laboratory.The as‐received rope was
separated at one end and intentionally cut at the other as show in
attached image 1711Image57402. The ¼ inch diameter rope had a
braided outer layer covering approximately 13 twisted inner strands.
Magnified inspection of the separation found mushroomed fiber ends
and partially fused strands indicative of adiabatic heating resulting
from high strain rate overstress separations of synthetic fiber ropes.
The longest strands were twisted as if they were part of a knot at the
time of separation. A dark band with a metallic sheen was visible on
the braided cover adjacent to the separation, see attached image
1711Image57407. A hand held x‐ray alloy analyzer revealed
significant amounts of aluminum in the darkest part of the band.

The docket did not include any line crew statements in regard to what
weak link may have been used for the tow.

A reasonable question for those World-Wide operations that use Tost
reels, would be. Is it uncommon for tow ropes to break, rather than
a prescribed weak link. If this was a rare anomaly, is there
some logical reason for it happening?

M Eiler


It is very common for a Tost reel rope to break before a white weak link (500daN) breaks. The slug on the glider end is anchored by a single overhand knot in the rope inside the slug, and with the strain from that knot, the rope is slightly weaker than the weak link. In the eight years that I towed with the system, we never broke a weak link, usually broke the rope right in front of the weak link.
  #107  
Old March 24th 19, 11:27 PM posted to rec.aviation.soaring
Roy B.
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Posts: 233
Default TOW PLANE Accident

Is it uncommon for tow ropes to break, rather than
a prescribed weak link. If this was a rare anomaly, is there
some logical reason for it happening?

We used the Tost reel system for many years on 2 tow planes and had the same experience: the ropes always broke near the weak link covering but not at the weak link. I suspect the issue is both the knot in the device and the constant flailing of the device and flexing of the rope near the weak link as it is rewound into the holder. We later abandoned the system.
ROY
 




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