Forums: Skydiving: General Skydiving Discussions:
Parachute Failure Rates

 


cliff  (B License)

Aug 21, 2003, 11:27 PM
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Parachute Failure Rates Can't Post

We often see warnings when we purchase skydiving gear.

For example, SSK sends a WARNNG that “one out of every 20,000-75,000 jumps results in death” “according to USPA…studies” That’s quite a broad estimation.

Further, they expect parachutes to malfunction “once in each 333 activations”.

I wonder if there has been any work done to make some estimation about the failure rate of mains vs. the failure rate of reserves? It seems to me that reserves would have a greater mean time between failures as a result of more positive openings with a spring-loaded pilot chute.

If mains and reserves have an equal failure rate of .003, then the parallel failure rate would be:

(.003)(.003)= .000009. In other words we could expect a double malfunction 9 times every million jumps, or once every 111,111 jumps.

I imagine that the “one out of every 20,000-75,000 jumps results in death” statistic is skewed by suicides and fatalities under functional parachutes (low turns, among others).

It seems that the military would be the folks most likely to maintain an accurate collection of such data, but I don’t see anything publicly listed.

Any thoughts?


mr2mk1g  (C 103449)

Aug 22, 2003, 1:10 AM
Post #2 of 12 (95626 views)
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Re: [cliff] Parachute Failure Rates [In reply to] Can't Post

mains fail (generally) because of packing errors.

VERY few reserves fail beacuse of packing errors.

The stats also take into account incidents caused by people doing slightly more risky things such as skyboard, CREW and wingsuit dives. This skews the stats further from the reseve stats.

Very few canopies suffer structural failure of some kind and when they do, it will almost always be due to a packing or maintainance error.

The main reason that a reserve fails is beacuse of problems caused by the failure of the main, eg fouling or bad body position after cutaway.


lasse  (Student)

Aug 22, 2003, 1:11 AM
Post #3 of 12 (95624 views)
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Re: [cliff] Parachute Failure Rates [In reply to] Can't Post

In reply to:
We often see warnings when we purchase skydiving gear.

For example, SSK sends a WARNNG that “one out of every 20,000-75,000 jumps results in death” “according to USPA…studies” That’s quite a broad estimation.

It seem to be in the one per 100,000 jumps range.

In reply to:
Further, they expect parachutes to malfunction “once in each 333 activations”.
Makes me start wondering if this isn't based on very old information. I'd expect about one per 1,000 range (actually about one reserve ride per 1,000 jumps).

In reply to:
I wonder if there has been any work done to make some estimation about the failure rate of mains vs. the failure rate of reserves? It seems to me that reserves would have a greater mean time between failures as a result of more positive openings with a spring-loaded pilot chute.

If mains and reserves have an equal failure rate of .003, then the parallel failure rate would be:

(.003)(.003)= .000009. In other words we could expect a double malfunction 9 times every million jumps, or once every 111,111 jumps.

I imagine that the “one out of every 20,000-75,000 jumps results in death” statistic is skewed by suicides and fatalities under functional parachutes (low turns, among others).
Most fatalities is of other causes than double malfunctions. About one out of ten fatalities (that is 1 out of 1,000,000 jumps) is due to double malfunction. In addition there might be double malfunctions that doesn't result in fatalities.


TrickyDicky  (C 103196)

Aug 22, 2003, 1:40 AM
Post #4 of 12 (95613 views)
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Re: [cliff] Parachute Failure Rates [In reply to] Can't Post

Remember, alot of fatalities now happen under a perfectly good main due to low hooks.

The only deaths Ive read about (in this country anyway) that werent low hooks were student main/reserve entanglements.


masher  (D 3806)

Aug 22, 2003, 1:44 AM
Post #5 of 12 (95610 views)
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Re: [TrickyDicky] Parachute Failure Rates [In reply to] Can't Post

The last APF magazine said that Australians had a 1 in ~750 chance of a reserve ride.


AggieDave  (D License)

Aug 22, 2003, 1:48 AM
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Re: [masher] Parachute Failure Rates [In reply to] Can't Post

I've always heard you have a 1 in 1000 chance of a malfunction. That's for both parachutes, so by every 1000th jump you should have a mal. If you jump your reserve 1000 times, well, you have problems.

That's just what I've been told and those numbers are averages/guesses, more then likely.


mr2mk1g  (C 103449)

Aug 22, 2003, 1:51 AM
Post #7 of 12 (95605 views)
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Re: [AggieDave] Parachute Failure Rates [In reply to] Can't Post

if cant be the same figure - you do a lot more stupid stuff with your main and a lot of care is taken over the packing of the reserve

the figure for a "shit happens" mal might be the same but MOST mal's on mains come from simple packing errors - you simply are not going to get the same numer of packing errors on a reserve.


MonkeyLip  (D 26041)

Aug 22, 2003, 2:32 AM
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Re: [mr2mk1g] Parachute Failure Rates [In reply to] Can't Post

My final answer is just skydive and have fun and remember not to be to complacent. Oh and find a rigger you trust to pack your reserve. Statistics are great however, they do not factor in good common sence and appropriate actions and decisions when the time arises. Example our dz owner has not had a cutaway in 5800 jumps, hence his first square reserve ride since his last cutaway. Yes he did buy beer! It kinda shoots the statistcs out the window.

MonkeyLip


mr2mk1g  (C 103449)

Aug 22, 2003, 2:56 AM
Post #9 of 12 (95584 views)
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Re: [MonkeyLip] Parachute Failure Rates [In reply to] Can't Post

too true - stats show nothing. 1 woman has a baby in 9 months - 9 women have a baby in 1 month.

If your jumping a non-radical canopy and not doing radical stuff in freefall the stats are far less than someone who does otherwise. Stats show very little cos this sport is so wide and varied that all the extreme elements skew the statistics so much.


Staso  (D 24665)

Aug 22, 2003, 6:18 AM
Post #10 of 12 (95528 views)
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Re: [cliff] Parachute Failure Rates [In reply to] Can't Post

In reply to:
If mains and reserves have an equal failure rate of .003, then the parallel failure rate would be:

(.003)(.003)= .000009. In other words we could expect a double malfunction 9 times every million jumps, or once every 111,111 jumps.

that whould be true if main and reserve were completely separated, but they are part of
one system. your math doesn't include main and reserve entanglement, activating reserve
at lower altitude, pulling reserve after spinning under main and thus in bad body position,
etc.

stan.


TrickyDicky  (C 103196)

Aug 22, 2003, 6:25 AM
Post #11 of 12 (95518 views)
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Re: [Staso] Parachute Failure Rates [In reply to] Can't Post

I think you're all looking at it wrongly.

Complacency is one of the biggest factors. Aslong as you take a little care over packing, you should never have a line-over. Take good care of your equipment and should should never get any opening damage.

Also, dont do swoop landings, and you are at less risk of hurting yourself.

I always thought a good skydive was one you walked away from.


davelepka  (D 21448)

Aug 22, 2003, 9:00 AM
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Re: [TrickyDicky] Parachute Failure Rates [In reply to] Can't Post

 
Your first point about many fatalities under open canopies are from low hooks needs to be re-considered. The stats have shown (in this forum in fact) that many open canopy fatalities were had by jumpers in the 200 to 500 jump range, jumping canopies at wing loadings that were just a touch high for thier experience, and the fatality was the result of a low turn into the wind, or a mix-up on an off field landing. These jumpers were not trying to perform a high performance landing of any kind.

Swoop landings are as safe as skydiving in general if people would give swooping the same consideration they gave skydiving in the begining. Have you ever heard of a student standing up in the middle of the first jump course and saying "I know you guys think I need to learn more, and practice more, but I'm going to jump right now anyway"? That is what happens everday at DZ's across the world. Senoir jumpers warn against rapid down-sizing, and aggresive landings without additional training, and the newbies don't listen. If a jumper was dedicated, and sought the proper training and coaching, and worked at it, he could place on the Pro Swooping Tour, and get a spot on the US team for the World Cup of Swooping in less than two years of total skydiving. I know this because I jump with just such a guy every weekend.

Your thoughts are coming from the right place, but keep in mind that at your level of experience there may be facets of certain issues that you cannot see.



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