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The Z-hills Double Fatal Speculation Thread

 

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grimmie  (D 18890)

Mar 30, 2013, 7:20 PM
Post #101 of 157 (2360 views)
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Re: [ChaoP] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

We had an AAD "save" at my DZ in February. The jumper was knocked unconscious on a tracking dive. A full face helmet probably saved her life on the landing into a chain link fence.

Just my 2 cents worth. Carry on...


nigel99  (D 1)

Mar 30, 2013, 8:45 PM
Post #102 of 157 (2318 views)
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Re: [airtwardo] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

Quote:
Ya always hear the 'in case of getting knocked out' justification for an AAD..which is valid.

However, what's the percentage of AAD fires because of unconsciousness vs. going low because of inattention?

Just want to point out that people aren't looking at their rigs as a 'system'. They are happy to have an AAD incase they are knocked out, but they are on a reserve that they are pushing the max limits on and would probably not survive the landing unconscious anyway, due their wingloading.

The biggest question on my mind is that it was stated that the instructor had pulled his reserve handle. Was the loop cut? I think that has substantial bearing on his fatality, because if the loop was not cut, he pulled above the AAD firing altitude and yet still did not have a functional reserve.


ChrisHoward  (D 28490)

Mar 31, 2013, 6:38 AM
Post #103 of 157 (2193 views)
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Re: [nigel99] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

In reply to:
Quote:
The biggest question on my mind is that it was stated that the instructor had pulled his reserve handle. Was the loop cut? I think that has substantial bearing on his fatality, because if the loop was not cut, he pulled above the AAD firing altitude and yet still did not have a functional reserve.

My guess would be that he pulled his reserve after seeing the students AAD fire. So most likely he pulled his reserve very close to or simultaneously to his own AAD firing.


Skydivesg  (D 10938)

Mar 31, 2013, 6:42 AM
Post #104 of 157 (2191 views)
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Re: [fencebuster] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

In reply to:
I personally think student AAD's should fire higher.


+1

More and more people agree with this. The AADs today can be set for what ever hard deck the user/owner wants. I do know of some schools who set them 300 feet higher.

It may or many not have helped these two people but unless you're John Sherman, it's becomig more and more difficult to come up with a sensible argument against the increased firing altitude. My guess is: after this incident more people will give greater consideration to doing the same thing.

Be the canopy pilot you want that other guy to be. .


(This post was edited by Skydivesg on Mar 31, 2013, 6:44 AM)


JohnSherman  (D 2105)

Mar 31, 2013, 10:56 AM
Post #105 of 157 (2099 views)
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Re: [Skydivesg] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

Quote:
It may or many not have helped these two people but unless you're John Sherman, it's becomig more and more difficult to come up with a sensible argument against the increased firing altitude.

I am all for raising the altitude "if it will help".
I see no proof that it will help. To the contrary my read is that it will not help. If we raise the altitude we will sit back and relax and it will be another 5 years and 10 more dead before we realize it did not work.
Show me one iota of proof that these failures would not have been failures if they had had more altitude.
So far the reasons and solutions for these incidents are based on video of on the ground performance all of which indicate complete failure without more dynamic pressure, which can only be increased with more speed. When you are at 750 feet and you AAD fires you are already going as fast as you are going to go. The same would be true at 1000 feet.


airdvr  (D 10977)

Mar 31, 2013, 12:22 PM
Post #106 of 157 (2048 views)
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Re: [JohnSherman] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

Agreed. Seems like things have to work perfectly from 750 feet. We already know they don't sometimes.


jonstark  (D 8298)

Mar 31, 2013, 12:28 PM
Post #107 of 157 (2047 views)
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Re: [JohnSherman] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

I know John that you are capable of making rigs that would work well outside either side of the TSO certification regimen's envelope. One that works well at high speeds and another that works well at low speeds. You must build one rig though for the market at large and, as a manufacturer of sport gear, you have the constraints that we, the consumers, have put you under. We want it clean, good looking, tight, small, on and on. Some of our wish list items impinge on the performance of the system as a whole.

The FAA and PIA have striven by the evolution of the TSO standards to make our equipment as safe as possible knowing full well that we will operate it outside it's published limitations. You've placarded it and warned us. You've worked with AAD manufacturers to interface. You've developed new and innovative systems to broaden the performance envelope.

No matter what you do you will always be hard pressed to make that perfect piece of equipment. The one that is "fool proof".

We, the consumers, must realize that you, the manufacturers, have limitations and we must be willing to compromise our desires to have the safety you do offer. If you tell me I can't have a 65 sq ft reserve that packs up like a pack of cigarettes and won't blow up at 250 MPH sobeit. If I insist on jumping one the onus is on me.

There will always be the exception to any rule. The unwitting student who, no fault of his own, will exceed the equipment limitations. These are the tragic losses. They are the real drivers of your evolutionary efforts though aren't they.

We applaud your efforts.


normiss  (D 28356)

Mar 31, 2013, 12:52 PM
Post #108 of 157 (2031 views)
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Re: [WickedWingsuits] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

Like you said, you had a few conclusions.
Laugh


Scrumpot  (D License)

Mar 31, 2013, 4:57 PM
Post #109 of 157 (1921 views)
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Re: [JohnSherman] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

In reply to:
Show me one iota of proof that these failures would not have been failures if they had had more altitude.

Do we know that the reserves were still contained ("locked") within their freebags upon impact in these incidents? If they were not, and the freebags had been "cleared", but full reserve inflation not yet attained - then it could be argued that some measure additional altitude might have mattered.

In reply to:
I see no proof that it will help. To the contrary my read is that it will not help. If we raise the altitude we will sit back and relax and it will be another 5 years and 10 more dead before we realize it did not work.

I hear what you are saying with this statement, and I do not necessarily disagree with this (as a concern) at all, either. However, just as I did here, I think the 2 points can (and perhaps should be) separated - and considered on their own separate, individual merits. In other words - even if full reserve-deployment hesitation (regardless method of activation) can be completely and successfully addressed (as I hear you are calling for) - might not still, in any case ALSO - activation altitude settings for (perhaps maybe even student-only, or specific in particular) AAD's be worthwhile considering?

I don't see as the one, even if you can almost nearly 100% assure full reserve deployment, inflation and deceleration "within parameters" (being resolved) - completely cancelling-out, or being mutually exclusive either, to the other. I guess that's what you mean by "if it will help", though? I agree - we should not just look at one perspective, without fully considering and addressing ALSO, the other.


chuteshack

Mar 31, 2013, 6:03 PM
Post #110 of 157 (1877 views)
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Re: [Scrumpot] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

i have it on good authority that the canopies were out of the freebags and almost fully inflated, but not enough time


BMFin

Mar 31, 2013, 7:06 PM
Post #111 of 157 (1834 views)
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Re: [fencebuster] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

In reply to:
I personally think student AAD's should fire higher.


+1

May I ask why is that? Is it because then you could chase the student untill his/hers AAD fires and you would still have some time to deploy your own reserve slightly lower?


JohnSherman  (D 2105)

Mar 31, 2013, 7:53 PM
Post #112 of 157 (1807 views)
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Re: [jonstark] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

Quote:
You must build one rig though for the market at large and, as a manufacturer of sport gear, you have the constraints that we, the consumers, have put you under. We want it clean, good looking, tight, small, on and on. Some of our wish list items impinge on the performance of the system as a whole.

You have got that right and I have been bitchin about it from the begining. I have refused to give those people the thing they wanted because I new they comprimised safety. As a result of other manufacturers caving to those demands we find our selves in the situation we have today. This is a life saving business and no one should comprimise safety for any reason, especially just to make a rig look good.
I don't agree about limitations. There shouldn't be any and if you get into the science you will find that the ones being violated don't really matter.
This is a science. These thing can be calculated. That is designs which have been tested can be calculated. PIA didn't and hasn't accounted for reserve pilot chute performance in their standards. This must be done. In the mean time there may be pilot chutes out there which are sub-standard in drag capability. That could be part of the problem. I ask you how do we verify that the pilot chut on our rig will do the job?
No one needs to die in this sport because of equipment failure. That must be our goal. Give no quarter and ask no quarter in this goal.


Skydivesg  (D 10938)

Mar 31, 2013, 8:17 PM
Post #113 of 157 (1785 views)
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Re: [JohnSherman] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

In reply to:
Quote:

I am all for raising the altitude "if it will help".
I see no proof that it will help........ Show me one iota of proof that these failures would not have been failures if they had had more altitude.

From: Chuteshack....

In reply to:
i have it on good authority that the canopies were out of the freebags and almost fully inflated, but not enough time

In this particular incident an extra couple hundred feet may have made a difference. I really don't understand those who argue against increasing the firing altitude for AADs. Assuming the information from Chuteshack is valid, in my view this is (at minimum) an "iota".

Be the canopy pilot you want that other guy to be.
.


nigel99  (D 1)

Mar 31, 2013, 8:33 PM
Post #114 of 157 (1775 views)
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Re: [Skydivesg] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

In reply to:
In reply to:
Quote:

I am all for raising the altitude "if it will help".
I see no proof that it will help........ Show me one iota of proof that these failures would not have been failures if they had had more altitude.

From: Chuteshack....

In reply to:
i have it on good authority that the canopies were out of the freebags and almost fully inflated, but not enough time

In this particular incident an extra couple hundred feet may have made a difference. I really don't understand those who argue against increasing the firing altitude for AADs. Assuming the information from Chuteshack is valid, in my view this is (at minimum) an "iota".

Be the canopy pilot you want that other guy to be.
.

More of a question than anything else. If AAD altitudes were raised 500ft. What would be the practical impact on the sport? What height would normal main deployment be, and normal breakoff from RW/FF etc?

Currently our Australian regulations say that you must have deployed by 1800ft. I doubt many people do this, but on some bigger way jumps I was recently deploying at 2.5k and under canopy at 2/2.1 and with one jump logged at 1900ft canopy open.

We can't safely raise exit altitudes due to hypoxia, and we probably already push the limits on top altitudes, anyway as sports skydivers.


Skydivesg  (D 10938)

Mar 31, 2013, 8:43 PM
Post #115 of 157 (1769 views)
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Re: [nigel99] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

In reply to:
More of a question than anything else. If AAD altitudes were raised 500ft. What would be the practical impact on the sport?

I don't advocate raisng them 500 feet but I see no reason not to up them to 1100 feet.

If you're that far into the basement, you need help.

Be the canopy pilot you want that other guy to be..


Ruffles  (A 42288)

Mar 31, 2013, 11:53 PM
Post #116 of 157 (1712 views)
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Re: [Skydivesg] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

Does the APA have an official position they preach in Instructor Training regarding chasing students to low altitudes & if so, what specifically do they teach? Im aware the chase is a big part of the curriculum, but have they set limits?


Andy9o8  (D License)

Apr 1, 2013, 8:28 AM
Post #117 of 157 (1584 views)
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Re: [JohnSherman] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

John, suppose the evidence (in this incident) eventually develops that both jumpers' reserve bags extracted from their containers essentially immediately upon PC launch, and both canopies extracted from their bags essentially immediately upon line stretch?


JohnSherman  (D 2105)

Apr 1, 2013, 8:59 AM
Post #118 of 157 (1548 views)
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Re: [Andy9o8] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

Quote:
John, suppose the evidence (in this incident) eventually develops that both jumpers' reserve bags extracted from their containers essentially immediately upon PC launch, and both canopies extracted from their bags essentially immediately upon line stretch?

That would be a wonderful thing. We would not be here talking. The jumpers would be enjoying a 30 second canopy ride.
If you are intimating that scenerio with the same outcome, I doubt it. However, if it did happen that way then the inflation speed of the canopy should be investigated as it would still be a TSO violation. This would be an easy thing to determine. Just jump them as a main to test.


airtwardo  (D License)

Apr 1, 2013, 9:37 AM
Post #119 of 157 (1521 views)
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Re: [JohnSherman] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

In reply to:
Quote:
John, suppose the evidence (in this incident) eventually develops that both jumpers' reserve bags extracted from their containers essentially immediately upon PC launch, and both canopies extracted from their bags essentially immediately upon line stretch?

That would be a wonderful thing. We would not be here talking. The jumpers would be enjoying a 30 second canopy ride.
If you are intimating that scenerio with the same outcome, I doubt it. However, if it did happen that way then the inflation speed of the canopy should be investigated as it would still be a TSO violation. This would be an easy thing to determine. Just jump them as a main to test.

John since you're more into the science of it....


There is some discussion on one of these threads regarding the opening time & altitude for varying freefall speeds.

Could that have been a significant factor?

Would (for example) the odds of getting an open reserve be lower going through 750' @ terminal plus 100 that they would @ terminal?


JohnSherman  (D 2105)

Apr 1, 2013, 11:34 AM
Post #120 of 157 (1469 views)
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Re: [airtwardo] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

Quote:
John since you're more into the science of it....


There is some discussion on one of these threads regarding the opening time & altitude for varying freefall speeds.

Could that have been a significant factor?

Would (for example) the odds of getting an open reserve be lower going through 750' @ terminal plus 100 that they would @ terminal?

You last paragraph is difficult to understand but, here is what I know: Canopies generally take the same amount of time to open at all speeds. Say they take 3 seconds after a cutaway they will generally take about 3 seconds at terminal. This is not exact just an observation. Speed does seem to speed up the opening a bit but not much. Perspective: At 20Fps after a cutaway you are accelerating away from the main. It takes about 1 second for the bridle to string out. Then the bag takes a load fop extraction. The bridle has used 1/3 of the allowed time for deployment. At 174FPS (terminal) that 16 feet deployes in a little over 10 feet using only a fraction of a second. Remember 3 seconds is the maximinum amount of time allowed for TSO testing. In reality that deployment is between 1 and 2 seconds. At 750 feet if things work as planed you will get about a 30 second canopy ride.


airtwardo  (D License)

Apr 1, 2013, 12:26 PM
Post #121 of 157 (1450 views)
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Re: [JohnSherman] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

In reply to:
Quote:
John since you're more into the science of it....


There is some discussion on one of these threads regarding the opening time & altitude for varying freefall speeds.

Could that have been a significant factor?

Would (for example) the odds of getting an open reserve be lower going through 750' @ terminal plus 100 that they would @ terminal?

You last paragraph is difficult to understand but, here is what I know: Canopies generally take the same amount of time to open at all speeds. Say they take 3 seconds after a cutaway they will generally take about 3 seconds at terminal. This is not exact just an observation. Speed does seem to speed up the opening a bit but not much. Perspective: At 20Fps after a cutaway you are accelerating away from the main. It takes about 1 second for the bridle to string out. Then the bag takes a load fop extraction. The bridle has used 1/3 of the allowed time for deployment. At 174FPS (terminal) that 16 feet deployes in a little over 10 feet using only a fraction of a second. Remember 3 seconds is the maximinum amount of time allowed for TSO testing. In reality that deployment is between 1 and 2 seconds. At 750 feet if things work as planed you will get about a 30 second canopy ride.

Sorry for not being clear...

My question was does it take essentially the same time & altitude to get an open canopy at 200mph as it does at 100 mph...all other factors being equal.


(This post was edited by airtwardo on Apr 1, 2013, 12:31 PM)


popsjumper  (D 999999999)

Apr 1, 2013, 1:46 PM
Post #122 of 157 (1395 views)
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Re: [airtwardo] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

Yeah...that was asked ages ago ...it'll be interesting to see if JS has anything additional to say after the clarification.


SethInMI  (A 47765)

Apr 3, 2013, 5:21 AM
Post #123 of 157 (1095 views)
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Re: [airtwardo] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

In reply to:
My question was does it take essentially the same time & altitude to get an open canopy at 200mph as it does at 100 mph...all other factors being equal.

It was probably mentioned up-thread, but one obvious non-equality for HD AAD activations is the AAD won't be in a burble, so it will fire higher, IIRC 250+ ft.


BMFin

Apr 3, 2013, 6:26 AM
Post #124 of 157 (1060 views)
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Re: [airtwardo] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

In reply to:
My question was does it take essentially the same time & altitude to get an open canopy at 200mph as it does at 100 mph...all other factors being equal.

I dont understand how time & altitude could both be the same.

If the altitude is the same, then the time must be shorter since the speed is higher.

On the other hand if the time is same, then the altitude must be more, since the speed is higher.


JohnSherman  (D 2105)

Apr 3, 2013, 8:15 AM
Post #125 of 157 (988 views)
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Re: [airtwardo] The Z-hills Double Fatal Speculation Thread [In reply to] Can't Post

Same time longer distance/altitude due to speed.


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