Very simplified statistical analysis of swooping.

[lkdiver 0]

Let’s assume that we have an idealized swooper. His swoop is affected exactly by seven independent variables: swoop starting height, amount of front riser input, harness input, altitude density, turbulence, duration of front riser input and rate of front riser release (I don’t know what the actual number of variables affecting swoop is – substitute whatever variables and number you like). Let’s further assume that each variable will affect the total altitude loss by exactly plus or minus 10 feet, and that the total error is a simple arithmetic sum of all individual errors.

That means that in this ideal case there are 128 possible error combinations, from -70 to +70 feet with following distribution:

-70 feet 1x
-50 feet 7x
-30 feet 21x
-10 feet 35x
+10 feet 35x
+30 feet 21x
+50 feet 7x
+70 feet 1x

From this simple calculation we can derive following conclusions:
- Even when individual variables are tightly controlled (+- 10 feet for starting height seems pretty good), if there is a lot of them, the resulting variability is significant (+- 70 feet)
- Most of the time random offsets will cancel out. In this case 112 attempts out of 128 will be +- 30 feet (87.5% of the time).
- Clearly this can give jumper a false sense of security that he is much better than he really is, luring him into lowering the swoop initiation height.
- Once in a blue moon (on average once out of 128 swoops), and what must seem like for no good reason at all, he will be facing deviation of -70 feet (a full 40 feet lower than his ‘normal’ low deviation of -30 feet). It is quite reasonable to assume that correcting this unusually large deviation successfully requires taking action much earlier than usual – probably in the stage where the jumper is concentrating on other things – and by the time he notices this it is too late. It is VERY important to realize that on this particular jump our swooper did not do anything out of ordinary, did not make any larger mistakes than usual – just all of those normal random little mistakes lined up in one direction.
- Of course this very low swoop happens on average once in 128 jumps, but this does not say anything about WHEN it will happen. It can happen on the next jump, or easily not for hundreds of jumps.

Obviously, in a real world distribution for each variable will not be binary, but more like normal distribution. This will have an unfortunate effect that while on average total error will be smaller, maximum possible error will be even larger than in this example.

The effect described here is independent of wing loading, however wing loading does play a significant role: lower wing loading translates into lower speed. Lower speed means smaller consequences on impact, and provides additional benefit of having more total time to react to the problem. There may be other factors in play as well – for example in general swoop on more loaded canopy starts higher, making it more difficult to estimate correct initiation height.

It would also seem that effect described here is unavoidable. Even executing 200 ‘perfect’ swoops does not mean that one is out of danger. The only hope for prevention is to understand this phenomenon, leave significant margin for error (much larger than seems necessary) and train to recognize signs of things going wrong early.

-Lubo.

[tcnelson 1]

37% of all statistics are made up...

Quote

Obviously, in a real world distribution for each variable will not be binary, but more like normal distribution.

gaussian distributions require independent, random events. the ability of the pilot to adjust the swoop based on experience makes any given swoop not random at all.

"Don't talk to me like that assface...I don't work for you yet." - Fletch
NBFT, Deseoso Rodriguez RB#1329

[PhreeZone 20]

Wow.. look at Ted all using big terms and all You'd think he was edumacated or something.

The better pilots are actually realizing these factors as they are in the middle of their swoops and are adjusting for them. Some do harness input , others adjust riser input, some do toggle input. But at somepoint all the good pilots are making adjustments all the way until their feet are on the ground, its the learning process of what adjustments to amek and when is what sets the good swoopers apart from the weekend warriers that throw hooks and hope.

Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

[tcnelson 1]

thanks for elaborating big daddy.

Quote

Wow.. look at Ted all using big terms and all You'd think he was edumacated or something.

plenty more where that came from; who wants to touch me?

"Don't talk to me like that assface...I don't work for you yet." - Fletch
NBFT, Deseoso Rodriguez RB#1329

[lkdiver 0]

…the ability of the pilot to adjust the swoop based on experience makes any given swoop not random at all.

Sure. I am only trying to show that the AMOUNT of adjustment in small number of cases may be much larger than in most cases. Recent swooping incidents clearly show that significant number of pilots do NOT have the ability to adjust the swoop correctly.

[AggieDave 6]

Quote

Recent swooping incidents clearly show that significant number of pilots do NOT have the ability to adjust the swoop correctly.

Recent incidents have shown that people are trying to swoop without the skill needed to work up to that skill level. They're jumping in over their heads and screwing up. Its not the swoop that kills, its strong headed 100-jump wonders (figurative term) that kills.

--"When I die, may I be surrounded by scattered chrome and burning gasoline."

[GQ_jumper 4]

you should fill out your profile so people have more of an idea of your experience when you are talking about swooping

History does not long entrust the care of freedom to the weak or the timid.
--Dwight D. Eisenhower

[lawrocket 3]

Quote

Let’s assume that we have an idealized swooper

That's quite an assumption. It is apparently this assumption that is causing so much difficulty.

I dont' believe that most people who pound in think that they are the idealized swooper. However, they seem to be trying to gt the ideal swoop instead of practicing and recognizing each variable you mentioned.

Violating good sense, they push the limits of all seven at once instead of pushing one at a time.

My wife is hotter than your wife.

[listo 0]

Wow, that is a mouthful! I am so glad that I am not a person wid uh edjumuhkashun. If I had to think about all of that I would surely pound in AGAIN. Ok, this is the second time today that I have had a gut laugh.

Don't get me wrong, I am sure that you put plenty of thought into your statistical analysis. However, who is going to have time to whip out their handy dandy calculator to decide which approach is going to be the best to take.

There is only one statistical factor that I am interested in... experience. I think that a major cause of swoop accidents happen because people spend too much time thinking and too little reacting. The funny thing is, you can't react to what you can't see and you can't see what you don't know. So now where do you go? Answer: You go back to your basic building blocks which comes from that little bag of tricks called E X P E R I E N C E.

Thank you for your brilliant analysis though, I am now enlightened.

Peace

Live today as tomorrow may not come

[YISkyDive 0]

Quote

You go back to your basic building blocks which comes from that little bag of tricks called E X P E R I E N C E.

If you get injured before you get the experience, you obviously have Nothing to rely on. This equation pertains more to a swooper with little experience.

Why did the gent. pound in, in S.Africa? He could have relied on experience to save him but obviously he didn’t realize he was low, until too late. Worst off, he was not that low, Perfect example of where this theory comes into play. A certain amount of events just tipped him off on the negative side and induced injury.

Any beginner swooper faces statistics, mathematics, and physics. The world [natural world, the thing we use to enjoy skydiving] functions only on these principals. No more, no less. Experience is ONLY developed when people get past the first set of swoops. Even then experienced people can get injured too, for what ever reason.

Quote

HOOK IT HIGH !!!!!

That’s fine if we hook high, but what if a beginner swooper is hooking his usual height, but is low and doesn’t realize until Extremely late, too late to save? A beginner pilot would be taken by surprise, and, if they don’t have that "E X P E R I N C E" to rely on, we add another thread to the long, sad incident reports.

Quote

who is going to have time to whip out their handy dandy calculator to decide which approach is going to be the best to take.

I think you strike up a good point, here. But if you are NOT educated on your approach (calculated) you’re bound to kiss the earth. Set up heights can change with degree of turn, heat, turbulence.. Obviously we NEED to calculate. Before I practice my approaches, I know for Darn sure where/ when/ how I want to be, before I even board the aircraft. Can my ideal set up change, sure. Must I know how to adjust in the air, Yes. But a basic calculation is extremely useful/ and important. I know when I go to the DZ and have down time, I’m reading notes I took from coaches, B.Germains book, and other useful documentation bits of documentation.

Calculation is necessary; personally, to say other wise could direct one into an area of danger.

I'm not trying to be combative by any means, please do not take this as an attack. But it is a rebuttal to those that argue against this theory.

I believe in this statistical approach to swooping, especially as a beginner pilot myself. It at least demonstrates that even if you do everything right, you can still get hurt.. And we all have seen that case here or there over the last couple of years.

[YISkyDive 0]

Quote

you should fill out your profile so people have more of an idea of your experience when you are talking about swooping

I don’t think this case needs a profile fill. This gent put out a good(in my opinion, please feel free to disagree) theory, and obviously it has nothing to do with his experience. Agree or disagree as you wish but there is 0 methodic teaching here, so experience is not necessary.

I know 16 year olds that have never jumped that can tell me what “was a good approach” and what “was a bad approach”, and tell me more about swooping than the person that initiated the turn. Theory and experience do not exist hand in hand.

Again, not being combative, just demonstrating the point i perosnally believe. Feel free to take it for what its worth.