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Statistical approach to PC in tow cutaway decision

 

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unkulunkulu  (C License)

May 29, 2013, 3:45 AM
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Statistical approach to PC in tow cutaway decision Can't Post

I was taught of my FJC to cutaway every malfunction, including PCIT. Now after absorbing some information I'm thinking about reconsidering this.

I've read a recent discussion on "why I'm not hooking up my RSL" and I agree with the argument to statistics: so far it's more likely saves you than kills you. But the OP of that thread argued that when RSL decides to kill you, there's really not much you can do (AC snag following a reserve destruction scenario).

But similar logic applies to main/reserve entanglement with respect to cutaway decision vs straight for the reserve: if you cutaway, you're giving yourself less control over what happens next, but is it statistically justified not to cutaway? I mean, how often do mains in the bag present problems in the cutaway scenario?


(This post was edited by unkulunkulu on May 29, 2013, 8:25 AM)


unkulunkulu  (C License)

May 29, 2013, 5:32 AM
Post #2 of 42 (4543 views)
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Re: [unkulunkulu] Statistical approach to total mal cutaway decision [In reply to] Can't Post

Ok, I kind of get that direct comparison to the RSL debate is incorrect, because the probabilities differ by an order of magnitude if not more, just wanted to know the statistic.


(This post was edited by unkulunkulu on May 29, 2013, 8:39 AM)


davelepka  (D 21448)

May 29, 2013, 5:41 AM
Post #3 of 42 (4530 views)
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Re: [unkulunkulu] Statistical approach to total mal cutaway decision [In reply to] Can't Post

 
There are no stats to use for any sort of analysis.

The RSL example, nobody knows how many times an RSL has worked without a problem because those instances are never reported. Furthermore, if someone pulls a reserve handle in short order after a cutaway, an RSL failure might occur and nobody would know. All we do know is when an RSL fails and causes harm such that it is apparent after the incident in an investigation. Even then, an RSL can fail and cause harm, but escape an investigation based on other factors of the incident.

Same thing for EPs as it applies to totals/PC in tow. The number of times that both handles, or just the reserve, were pulled and things worked out fine are unknown. All we know is the handful of times that one or the other didn't work out, and it was clear in the aftermath that the handle sequence was the problem.

This is one of those areas that always sparks a good debate because there is no one 'definitive' answer.


airtwardo  (D License)

May 29, 2013, 7:17 AM
Post #4 of 42 (4475 views)
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Re: [davelepka] Statistical approach to total mal cutaway decision [In reply to] Can't Post

In reply to:
This is one of those areas that always sparks a good debate because there is no one 'definitive' answer.


~Just to add

This is one of those types of scenarios where you have a couple of options & either one 'could be' right or wrong going into the situation.

Making it even more confusing, what's right one given jump may not be on the next. There are a lot of smaller situational variables that need to be considered 'in the moment' to really go with any single 'one size fits all' rule.

I like what the OP did/is doing ~ question - discuss - learn - decide.

Everything isn't always 'cut & dried' here. When people sometimes say "You don't even know what you don't know" it's stuff like this they're referring to.

Like an onion there's a lot of layers, smart ones peel it back and look hard at each layer & then decide 'what leads to which & when' and what procedure is best for them.

They drill it and if the time comes - use it and hope for the best...knowledge is power. Wink


evan85  (C 41367)

May 29, 2013, 7:30 AM
Post #5 of 42 (4463 views)
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Re: [unkulunkulu] Statistical approach to total mal cutaway decision [In reply to] Can't Post

As a low-jump number jumper, I've been very interested in these discussions as well. I have no intentions of disconnecting my RSL anytime soon as I feel it's great insurance for someone like me who hasn't had to cutaway yet.

That said, to the issue at hand -- whether to cutaway a total mal or not -- I've seen a lot of info in different places, but would love to have someone summarize to pros and cons. I understand that some of those pros and/or cons only apply in certain situations, so maybe that could be made clear too. Hoping to make an informed decision for myself but the information I've seen is a little too spread out and all over the place. Thanks.


Zlew  (D 21616)

May 29, 2013, 7:49 AM
Post #6 of 42 (4450 views)
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Re: [evan85] Statistical approach to total mal cutaway decision [In reply to] Can't Post

Might want to clarify- Are you talking about a true "total" with nothing out at all, or are you talking about a PC in tow?

A true total, like just not being able to find you hackey, for me there is no reason to cut away. The debate is usually around PC in tow (or similar) since something is out but your container is still closed...and it may or may not deploy at some point.

For either...whichever game plane you come up with, execute it quickly. :)


unkulunkulu  (C License)

May 29, 2013, 8:23 AM
Post #7 of 42 (4416 views)
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Re: [Zlew] Statistical approach to total mal cutaway decision [In reply to] Can't Post

So in English a PCIT is not considered a total? Then the title and the question should've been about PCIT specifically.


Zlew  (D 21616)

May 29, 2013, 8:34 AM
Post #8 of 42 (4404 views)
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Re: [unkulunkulu] Statistical approach to total mal cutaway decision [In reply to] Can't Post

I looked it up, and it looks like I was wrong. SIM says PCIT is a "total". When I started, a total was "nothing" was out...but that was also in the days of spring loaded student main rigs where you could "pull" the main rip and have nothing happen.

Might just be semantic...but probably me just being old and out dated :)

a) A total malfunction includes deployment handle problems (unable to locate or extract the main parachute deployment handle), pack closure, and a pilot chute in tow.


Edit to add- To me though, what I would do in the situation where I couldn't find my handle and had nothing out...would be different than what I would do in a PCIT.


(This post was edited by Zlew on May 29, 2013, 8:36 AM)


wmw999  (D 6296)

May 29, 2013, 9:04 AM
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Re: [Zlew] Statistical approach to total mal cutaway decision [In reply to] Can't Post

I'll admit I'd consider a PCIT to be a PCIT, and not a total -- for all the same reasons that you do.

Either way, I don't cut away from either a total or a PCIT (I have experience with both). In my case, it worked, but it's not a guarantee with a PCIT. Sometimes the best-thought-out plan turns out not to be ideal because of specific circumstances, or just plain bad luck.

But having thought it out nearly always puts one ahead.

Wendy P.


airdvr  (D 10977)

May 29, 2013, 10:01 AM
Post #10 of 42 (4337 views)
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Re: [evan85] Statistical approach to total mal cutaway decision [In reply to] Can't Post

Something to keep in mind; there has been a lot of discussion lately about trouble with reserves deploying when the main is still in the container. One of the theories is that the main still being in the container makes the reserve more difficult to deploy. So, your EP isn't over until you've got a reserve over your head. You might have to give the reserve pack a nudge or three with your elbow. Remember, never give up!


airtwardo  (D License)

May 29, 2013, 10:06 AM
Post #11 of 42 (4330 views)
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Re: [airdvr] Statistical approach to total mal cutaway decision [In reply to] Can't Post

airdvr wrote:
Something to keep in mind; there has been a lot of discussion lately about trouble with reserves deploying when the main is still in the container. One of the theories is that the main still being in the container makes the reserve more difficult to deploy. So, your EP isn't over until you've got a reserve over your head. You might have to give the reserve pack a nudge or three with your elbow. Remember, never give up!

THIS....and I've found that cussing it seems to help. Angelic


popsjumper  (D 999999999)

May 29, 2013, 10:27 AM
Post #12 of 42 (4301 views)
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Re: [airtwardo] Statistical approach to total mal cutaway decision [In reply to] Can't Post

airtwardo wrote:
airdvr wrote:
Something to keep in mind; there has been a lot of discussion lately about trouble with reserves deploying when the main is still in the container. One of the theories is that the main still being in the container makes the reserve more difficult to deploy. So, your EP isn't over until you've got a reserve over your head. You might have to give the reserve pack a nudge or three with your elbow. Remember, never give up!

THIS....and I've found that cussing it seems to help. Angelic

I was more proactive. I included screaming.
Fortunately, I didn't get to the pissin' in my pants stage.


skyjumpenfool  (Student)

May 29, 2013, 10:31 AM
Post #13 of 42 (4295 views)
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Re: [airtwardo] Statistical approach to total mal cutaway decision [In reply to] Can't Post

airtwardo wrote:
airdvr wrote:
Something to keep in mind; there has been a lot of discussion lately about trouble with reserves deploying when the main is still in the container. One of the theories is that the main still being in the container makes the reserve more difficult to deploy. So, your EP isn't over until you've got a reserve over your head. You might have to give the reserve pack a nudge or three with your elbow. Remember, never give up!

THIS....and I've found that cussing it seems to help. Angelic

Nope!! I've found sweet talk to be much more effective... "come on baby! Come on sweetheart, open! Open baby! Papa loves you! Give me some material."

Wink


Ron

May 29, 2013, 12:17 PM
Post #14 of 42 (4232 views)
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Re: [unkulunkulu] Statistical approach to PC in tow cutaway decision [In reply to] Can't Post

Quote:
Now after absorbing some information I'm thinking about reconsidering this.

Bravo. Not all the answers you were giving in the FJC are the best solutions. They are the best solutions for that time in your career.

Quote:
I mean, how often do mains in the bag present problems in the cutaway scenario?

You are just never going to get enough data to get a solid sample size.

1. The occurrence is just not often enough to get great data.
2. The data is unreported more than it is reported.

The only thing you could do is read the incident reports over the years and see how many died doing "X" and how many died doing "Y". But without the rate of "X" and "Y" you really have no solid data.

I'd love to see the data. I just don't think we are going to get any great data.


erdnarob  (D 364)

May 29, 2013, 2:55 PM
Post #15 of 42 (4177 views)
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Re: [unkulunkulu] Statistical approach to PC in tow cutaway decision [In reply to] Can't Post

I have never heard about statistics on this touchy subject (ie. pilot chute in tow). I have discussed that subject many times with other skydivers. But here are my thoughts about it. Should a pilot chute in tow situation occurs to me, I wouldn't cut away since there is nothing to cut away from. OTOH, I would dip slightly a shoulder and pull my reserve. Dipping a shoulder would allow the air to flow better and catch the pilot chute avoiding that way a possible case of the pilot chute being caught in the burble. If the pilot chute is being launched as fast as possible and straight up, there is less chance for entanglement of the reserve with the main pilot chute. Now, for people who believe that a reserve extraction is more difficult while the main is still in its container, it shouldn't because the companies test jumpers are testing this situation. I have had two total with my Vector III-size 348 (I couldn't find my hackey) and decided to pull my reserve. I have been happily surprised to find out how fast the deployment was. I pulled and within few seconds when I took a look, the reserve was fully deployed. It was a PD 160 reserve. The main parachute was a Katana 170 which makes a pack quite thight.


airtwardo  (D License)

May 29, 2013, 7:36 PM
Post #16 of 42 (4108 views)
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Re: [erdnarob] Statistical approach to PC in tow cutaway decision [In reply to] Can't Post

erdnarob wrote:
I have never heard about statistics on this touchy subject (ie. pilot chute in tow). I have discussed that subject many times with other skydivers. But here are my thoughts about it. Should a pilot chute in tow situation occurs to me, I wouldn't cut away since there is nothing to cut away from. OTOH, I would dip slightly a shoulder and pull my reserve. Dipping a shoulder would allow the air to flow better and catch the pilot chute avoiding that way a possible case of the pilot chute being caught in the burble. If the pilot chute is being launched as fast as possible and straight up, there is less chance for entanglement of the reserve with the main pilot chute. Now, for people who believe that a reserve extraction is more difficult while the main is still in its container, it shouldn't because the companies test jumpers are testing this situation. I have had two total with my Vector III-size 348 (I couldn't find my hackey) and decided to pull my reserve. I have been happily surprised to find out how fast the deployment was. I pulled and within few seconds when I took a look, the reserve was fully deployed. It was a PD 160 reserve. The main parachute was a Katana 170 which makes a pack quite thight.


Not be too picky - But...Blush

Personally when I'm just about out of parachutes, I try to get the last one launched as perfectly as possible for the situation.

Flat & stable to start, hands in on handles then pulling my knees up so I'm in the old 45 degree angle 'sit up' position as they use to call it...back when both parachutes had spring loaded pilot chutes.

Plenty of fast clean air going over the container so there won't be any hesitation. Your shoulders are 'square' so the bag should leave straight & balanced...dipping to one side too much could launch the bag screwy, might load one side more than the other - might leave spinning leaving the canopy to open with twists.

Also by sitting up, the two bridles have a bit more of a separate path to hopefully stay on.

Of course this shouldn't be done in an emergency if you've never 'sat up' when deploying...but it's a good tool to have.



Also ~ the reserve hesitation with a full main pack tray scenario has been talked about a few times before.

Though correct when you say the TSO tests for that, it doesn't test for every possible canopy combination. Wouldn't be cost effective...what IS cost effective is making sure the combination you test in the TSO works perfectly.

There have been too many documented real world hesitations and too many table totals to turn a blind eye to the possibility of that happening. Just sayin' Wink


sundevil777  (D License)

May 29, 2013, 10:14 PM
Post #17 of 42 (4069 views)
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Re: [airtwardo] Statistical approach to PC in tow cutaway decision [In reply to] Can't Post

In reply to:
by sitting up, the two bridles have a bit more of a separate path to hopefully stay on.

I think being flat would provide the greatest separation.


unkulunkulu  (C License)

May 29, 2013, 11:14 PM
Post #18 of 42 (4041 views)
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Re: [Ron] Statistical approach to PC in tow cutaway decision [In reply to] Can't Post

Ron wrote:
The only thing you could do is read the incident reports over the years and see how many died doing "X" and how many died doing "Y". But without the rate of "X" and "Y" you really have no solid data.
Another important thing is that I don't want solid representative "X" to "Y" ratio, I would want the ratio between negative and positive results on "X", and that is much harder to acquire. I will try asking S&TA at our not too little DZ for the information.


unkulunkulu  (C License)

May 29, 2013, 11:17 PM
Post #19 of 42 (4039 views)
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Re: [airtwardo] Statistical approach to PC in tow cutaway decision [In reply to] Can't Post

Quote:
Also by sitting up, the two bridles have a bit more of a separate path to hopefully stay on.
I would say that sitting up brings the main bridle closer to the reserve, no?


Premier skydiverek  (C 41769)

May 30, 2013, 2:07 AM
Post #20 of 42 (4011 views)
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Re: [unkulunkulu] Statistical approach to PC in tow cutaway decision [In reply to] Can't Post

unkulunkulu wrote:
Quote:
Also by sitting up, the two bridles have a bit more of a separate path to hopefully stay on.
I would say that sitting up brings the main bridle closer to the reserve, no?

Correct.


airtwardo  (D License)

May 30, 2013, 8:54 AM
Post #21 of 42 (3917 views)
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Re: [skydiverek] Statistical approach to PC in tow cutaway decision [In reply to] Can't Post

skydiverek wrote:
unkulunkulu wrote:
Quote:
Also by sitting up, the two bridles have a bit more of a separate path to hopefully stay on.
I would say that sitting up brings the main bridle closer to the reserve, no?

Correct.

No...not really.

If you've ever seen up close what a flat & stable deployment with a spring-loaded pilot chute looks like...especially on someone 'my size' creating a huge burble - I think the point would be clearer.

Yes it may seem in theory you've brought the bridels closer...but the separation seems to come from the fact the relative wind is going 'up' along the pack trays, bottom to top.

And since the reserve PC is 'up' above the main...it launches forward of it. Flat and stable that reserve PC does some dancing around back there...I've even seen them go up a couple feet- and come back down on a large person.

My point is...dropping a shoulder from a flat & stable - pushes it 'back' right at the main PIT.

The 'dancing pilot chute' thing is WHY the hand-deploy PC was invented BTW. To get it into clean air immediately.

Big jumpsuits doing big formations 'back in the day' often had vids of PC's having 5 sec. and longer hesitations trying to find clean air.

That's why many of us learned to 'sit-up' at pull time.


rustywardlow  (D 18809)

Jun 2, 2013, 9:52 PM
Post #22 of 42 (3738 views)
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Re: [unkulunkulu] Statistical approach to PC in tow cutaway decision [In reply to] Can't Post

I just had a pilot chute in tow last weekend and I can tell you right now proper procedure is to always cutaway then pull your reserve. Pull your handles in order. After the reserve deploys there is less pressure on the main pack tray and it will likely come open. if you don't cutaway you can end up with two canopies out or worse batman a main reserve entangelment. Out of seqence deployments kill so always always always pull your handles in the proper order. There is no reson not too.
PiratePirate
In reply to:


sundevil777  (D License)

Jun 2, 2013, 11:58 PM
Post #23 of 42 (3724 views)
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Re: [rustywardlow] Statistical approach to PC in tow cutaway decision [In reply to] Can't Post

I can understand taking a position to cutaway first.

I cannot understand your making assertions that are not true, assertions that you would understand to not be true if you had read this or many other threads on this subject.


tkhayes  (D 18764)

Jun 3, 2013, 1:19 AM
Post #24 of 42 (3716 views)
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Re: [unkulunkulu] Statistical approach to PC in tow cutaway decision [In reply to] Can't Post

How about you check you gear, and then you never have a PC in tow? It is probably the least common malfunction, and certainly ranks up there in prevent-ability.

It is just as preventable as the 'I left my legstraps undone' malfunction.


milehigheric  (C License)

Jun 3, 2013, 3:25 AM
Post #25 of 42 (3690 views)
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Re: [rustywardlow] Statistical approach to PC in tow cutaway decision [In reply to] Can't Post

rustywardlow wrote:
I just had a pilot chute in tow last weekend and I can tell you right now proper procedure is to always cutaway then pull your reserve. Pull your handles in order. After the reserve deploys there is less pressure on the main pack tray and it will likely come open. if you don't cutaway you can end up with two canopies out or worse batman a main reserve entangelment. Out of seqence deployments kill so always always always pull your handles in the proper order. There is no reson not too.

Cutting away first does not prevent an out of sequence deployment. Who's to say your cutaway main is not going to leave as your reserve snivels and become entangled? Everyone is entitled to their own opinions, but I see cutting away first as taking away an option you may have wanted later.

edit - fixed formatting


(This post was edited by milehigheric on Jun 3, 2013, 4:09 AM)


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