How do you get to thousands of jumps with no cutaways?

[The111 0]

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That wouldn't affect the Poisson distribution based on jumps between events.

I agree that from a pure statistical point of view (i.e. assuming every deployment/packjob/body-position is the same), time in the sport would not affect the malfunction rate. BUT... I am assuming that people who have been in the sport for 3000 jumps have better packing methods, body position, and are generally safer than people with 100 jumps.

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[happythoughts 0]

Canopy.

About every 80-100 jumps, I get twisted up. I blame it on bad body position. I still jump an old Sabre. When it twists up, it continues to fly straight and level while I can kick out the line twists.

If an elliptical twists up, it generally starts spinning like a &^$% and heads for the ground, you have to chop it quick.

I blame high performance canopies for most of the chops. Personal opinion.

[kallend 1,625]

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Thanks for the Poisson numbers John. I was too lazy to do it. In response to your question about too many malfunctions for low number jumpers I think the most likely reason is body position. This is strongly correlated with jump numbers....

Off topic, are you doing 10-way at Nationals this year?

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The only sure way to survive a canopy collision is not to have one.

[darkwing 4]

Tricky devil, you have turned off PM...

Doing 10-way at the Nationals? Nope. You know how us academics mostly can't get time off that time of year. I am taking two teams to Lake Wales for their 10-way competition over Christmas/New Years though. Took one team last year and everyone had so much fun even more people want to go this year. Maybe I'll captain two teams at the same time.

-- Jeff
My Skydiving History

[mikkey 0]

I am not a statistician. Last time I knew something about Poisson was at University 25 years ago.....

I just think that doing a likelihood calculation based purely on number of jumps for an event that is so dependent on skills (both freefall and packing) and the canopy type you are jumping is difficult. Sunday I talked to a guy doing his 300'th who just had his 4th cut-away due to a line over. I have seen him pack and I am not surprised.

So saying that there is only 0.25% of chance that you had no mal at 3000 jumps seems very low. Thats one in 400. On the other hand saying that 36 out of 100 jumpers who have 500 jumps should have no mal seems quite high (based on personal observation).
I think other factors like canopy type need to be included to get "realistic" numbers. But this is only based on "gut" feel on my part.

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When people look like ants - pull. When ants look like people - pray.

[sundevil777 93]

I think that a good way to decrease your chances of a malfunction is to use a canopy that is not so sensitive to body position - meaning a lightly loaded canopy, with an aspect ratio that is not extreme.

I think this same logic also applies to reserves.

Isn't this part of the reason why reserves have conservative aspect ratios?

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[TrickyDicky 0]

I got entangled with my main on jump 12 on my first 5s FF. Cut away got a reserve. Does that count as trigger happy or just shit learner?

UK Skydiver for all your UK skydiving needs.

[kallend 1,625]

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I am not a statistician. Last time I knew something about Poisson was at University 25 years ago.....

I just think that doing a likelihood calculation based purely on number of jumps for an event that is so dependent on skills (both freefall and packing) and the canopy type you are jumping is difficult. Sunday I talked to a guy doing his 300'th who just had his 4th cut-away due to a line over. I have seen him pack and I am not surprised.

So saying that there is only 0.25% of chance that you had no mal at 3000 jumps seems very low.

I am sure you noticed that I put two capitalized "IF"s in the preamble.

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Thats one in 400. On the other hand saying that 36 out of 100 jumpers who have 500 jumps should have no mal seems quite high (based on personal observation).
I think other factors like canopy type need to be included to get "realistic" numbers. But this is only based on "gut" feel on my part.

The Poisson gives the probability distribution of events that occur at random, like deaths from lightning strikes or horse kicks in the cavalry, arrival of photons from the microwave background, radioactive decay, etc.


My "gut" feeling is that the actual distribution will be pretty close to Poisson, with some skew towards increased malfunctions at low jump numbers.

USPA asks about malfunctions on its annual renewal form. If USPA would only release the data, we could compare with the Poisson and maybe reach some real conclusions about the effect of skill or canopy type. In the absence of any actual data, your guess is as good as any.

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The only sure way to survive a canopy collision is not to have one.

[skyflyeratwood 0]

Hey Saskia!
Love ya web site! Jokes are sweet! I think you explained my cat purrfectly! :)

Ever stop to think and forget to start again

[slayer21016 2]

Out of 3500+ jumps i've made to date i've only had 2 the first 1 at 2200 doing a tandem and number 2 at rantoul (on my wffc video) this year. it seems that most of the people i know have had a much larger number of cutaways than me but i feel this is because they don't try and fix or figure out the problems before cutting it. i've had mals that others said they would have cutaway, but i worked with the problems i had and got out of them with plenty of altitude to spare. and it's the i would have cut that away answer that makes me feel that some will chop a lot faster than others thus giving figures that some have a low number of cutaways while others have a higher number. I'm sure that if asked a lot of the people who have thousands of jumps and a low number of cutaways will also say that they have had questionable situations that could have gone ether way.

But when in doubt whip it out.