Is skydiving really safe?

[brodg 0]

Hi everybody. I was doing some math and giving some thought to the skydiving safety statistics. We always hear that skydiving can be a very safe sport, and I truly believe that, but statistics can disagree. I believe this is because safety depends hugely on how we approach the sport and how conscious we are. However for the sake of this discussion I will forget about this and present my case assuming everyone has the same odds of getting injured.

My reasoning is as follows, let´s take year 2013 as an example: 24 fatalities in 3.200.000 jumps, in other words a fatality every 133.333 jumps. That doesn't sound so bad, doesn't it? In fact if you give that number to someone who doesn't jump they might say the sport is very safe. This is because we assume that we have a chance of 1 in 133.333 (0.00075%) of getting killed, and while this might be true for someone that only does a single jump in his whole life, it's not even close for a regular jumper.

I want to be an active regular jumper so I wanted to know how this odds apply to me. I assumed an active jumper does around 10.000 jumps throughout his life. If this is the case then the statistics change from 1 in 133.333 (0.00075%) to 10.000 in 133.333 (7.5%). That's right!: If everyone has the same chance of dying per jump and you want to do 10.000 jumps in your life, you have a 7.5% chance of getting killed! How fucked up is that?

Another funny way to see it is that by every jump you make you are buying 1.950 lottery tickets, if one of them hits the jackpot you're a goner. We can put it a million different ways, but you get the idea.

I don't want to be a fun killer and I know this topic can be tabu for some people, but I think everyone should know how dangerous this sport can be in order to take safety seriously. I said that I would assume that everyone has the same chance of getting hurt, and I want to clarify that this is far from true; if you do things the right way then this odds can be lowered extremely. I saw a video the other day where Rook Nelson said "skydiving is like crossing a street: if you just run across it without looking sideways it is indeed very dangerous, but if you do it carefully it can be a really safe sport" and I couldn't agree more with that. So remember, safety depends only on you, be safe out there and have fun!

[A.Stieda 0]

Thats not how statistics work. If I was to use your example numbers (and assumptions), EVERY jump would have a 1 in 133,333 chance of a fatality. That means your first jump has the same odds as your 10,000th jump. If you are on your 10,000th skydive, it does not mean you suddenly are at much higher risk of that jump being a fatality.

[Remster 24]

No, it's not. You can do everything right and still die. If you can't handle that, take up bowling.

Remster

[brodg 0]

A.Stieda

Thats not how statistics work. If I was to use your example numbers (and assumptions), EVERY jump would have a 1 in 133,333 chance of a fatality. That means your first jump has the same odds as your 10,000th jump. If you are on your 10,000th skydive, it does not mean you suddenly are at much higher risk of that jump being a fatality.

I never said that if you are on your 10.000th skydive you are suddenly at much higher risk. All I'm saying is if every time you jump you have, for example, a 1% chance of dying, then the probability of dying in 50 jumps is 1x50=50%, which is not the same as the probability of dying in you 50th jump (which still is 1%).

[mattjw916 2]

I hope you are better at skydiving than statistics...

The risk isn't cumulative, it's the same for each jump, since each jump is an independent event with no connection to previous events. Just like a coin toss.

NSCR-2376, SCR-15080

[brodg 0]

mattjw916

I hope you are better at skydiving than statistics...

The risk isn't cumulative, it's the same for each jump, since each jump is an independent event with no connection to previous events. Just like a coin toss.

OMFG I never said the risk is cumulative!!

[Rover 9]

No

2 wrongs don't make a right - but 3 lefts do.

[topdocker 0]

brodg

If this is the case then the statistics change from 1 in 133.333 (0.00075%) to 10.000 in 133.333 (7.5%). That's right!: If everyone has the same chance of dying per jump and you want to do 10.000 jumps in your life, you have a 7.5% chance of getting killed! How fucked up is that?

Completely effed up. Statistically speaking that is. You made the odds cumulative right there and they are not.

top

Jump more, post less!

[DocPop 1]

brodg

.... the probability of dying in 50 jumps is 1x50=50%,

Holy shit!

So, 50% of jumpers don't make it to 51 jumps?

"The ground does not care who you are. It will always be tougher than the human behind the controls."

~ CanuckInUSA

[brodg 0]

topdocker

*** If this is the case then the statistics change from 1 in 133.333 (0.00075%) to 10.000 in 133.333 (7.5%). That's right!: If everyone has the same chance of dying per jump and you want to do 10.000 jumps in your life, you have a 7.5% chance of getting killed! How fucked up is that?

Completely effed up. Statistically speaking that is. You made the odds cumulative right there and they are not.

top

I fail to see how I made the odds cumulative. I'll use the same example as above to prove my point:

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All I'm saying is if every time you jump you have, for example, a 1% chance of dying, then the probability of dying in 50 jumps is 1x50=50%, which is not the same as the probability of dying in you 50th jump (which still is 1%).

[Bluhdow 31]

brodg

All I'm saying is if every time you jump you have, for example, a 1% chance of dying, then the probability of dying in 50 jumps is 1x50=50%, which is not the same as the probability of dying in you 50th jump (which still is 1%).

No dude. That's dumb.

You ARE saying that the risk is cumulative. That's exactly what you're implying above.

1. You don't understand statistics.
2. You might not even understand what you just wrote.
3. Skydiving still isn't safe.

Apex BASE
#1816

[ghost47 18]

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I never said that if you are on your 10.000th skydive you are suddenly at much higher risk. All I'm saying is if every time you jump you have, for example, a 1% chance of dying, then the probability of dying in 50 jumps is 1x50=50%, which is not the same as the probability of dying in you 50th jump (which still is 1%).

So, by your method, if every time you jump you have a 1% chance of dying, then the probability of dying in 100 jumps is 1% x 100 = 100%?

To illustrate why that's wrong:

What are the odds, when you flip a coin, that you get heads? 50%, right?

So if you flip a coin twice, what are the odds that you get heads at least once? (Hint, it's not 2 x 50% = 100%.)

[brodg 0]

DocPop

*** .... the probability of dying in 50 jumps is 1x50=50%,

Holy shit!

So, 50% of jumpers don't make it to 51 jumps?




Hahaha you missed this part:

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if every time you jump you have, for example, a 1% chance of dying

[brodg 0]

ghost47

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I never said that if you are on your 10.000th skydive you are suddenly at much higher risk. All I'm saying is if every time you jump you have, for example, a 1% chance of dying, then the probability of dying in 50 jumps is 1x50=50%, which is not the same as the probability of dying in you 50th jump (which still is 1%).

So, by your method, if every time you jump you have a 1% chance of dying, then the probability of dying in 100 jumps is 1% x 100 = 100%?

To illustrate why that's wrong:

What are the odds, when you flip a coin, that you get heads? 50%, right?

So if you flip a coin twice, what are the odds that you get heads at least once? (Hint, it's not 2 x 50% = 100%.)

Yes, you're right bro.. Lol i was so sure of my numbers I'll correct the math and post the right probabilities

[excaza 1]

brodg

All I'm saying is if every time you jump you have, for example, a 1% chance of dying, then the probability of dying in 50 jumps is 1x50=50%, which is not the same as the probability of dying in you 50th jump (which still is 1%).

Vegas must love you

[Di0 1]

ghost47

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I never said that if you are on your 10.000th skydive you are suddenly at much higher risk. All I'm saying is if every time you jump you have, for example, a 1% chance of dying, then the probability of dying in 50 jumps is 1x50=50%, which is not the same as the probability of dying in you 50th jump (which still is 1%).

So, by your method, if every time you jump you have a 1% chance of dying, then the probability of dying in 100 jumps is 1% x 100 = 100%?

To illustrate why that's wrong:

What are the odds, when you flip a coin, that you get heads? 50%, right?

So if you flip a coin twice, what are the odds that you get heads at least once? (Hint, it's not 2 x 50% = 100%.)

Good example, in this case it's easy to show, all the possible scenarios are:

HH
TT
HT
TH
So the chances of getting at least one Head are, of course, 75% *. It's still true the intuitive concept that "the more you jump, the more you risk", i.e. the chances of getting at least ONE HEAD (mmhhh. LoL?) for a high number of toss will quickly approach 100%.


* As a generalization, if I remember statistics correctly, this are masochistically ** independent process, so if you have "remove" the chance that they both happen at the same time, which is what you do wrong when you sum them, in this case the 3/4 comes from:
H(1)+H(2)-H(1)*H(2) = 1/2+1/2-1/2*1/2 = 3/4.
Something along those lines. Hover this doesn't really apply to skydiving, where you only need to die once to stop the winning streak.



*** EDIT: That's self-correction but I am going to leave it that way because it's awesome. I meant to say "stochastic"

I'm standing on the edge
With a vision in my head
My body screams release me
My dreams they must be fed... You're in flight.

[ghost47 18]

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Yes, you're right bro.. Lol i was so sure of my numbers

Here's the method I've always used:

If you have a 1% chance of dying, that means you have a 99% chance of living.

So what are the odds of living after one jump? 99%. Two jumps? 99% * 99%. Three jumps? 99% * 99% * 99%. Etc. After 100 jumps you'll get 36.6% chance of living. That means, after 100 jumps, you have a 63.4% chance of dying.

That's of course assuming that you have a 1% chance of dying.

If, instead, you have a 0.001% chance of dying each jump (1 out of 100,000), then you have a 99.999% chance of living. Over 10,000 jumps, you get 90.48% chance of living. Which means 9.52% chance of dying.

Disclaimer: I haven't taken a math class, or significantly used math in my life, for close to 20 years. So I could be wrong.

ETA: However, once you get to the 9,999 jump, your odds of dying on Jump 10,000 would still be 0.001%. As would be true with any other jump you do.

[FlyingRhenquest 1]

Um, your math's wrong. If I want to do 10000 jumps in my life, I have a 100% chance of getting killed. Maybe just a 7.5% chance of getting killed while skydiving.

Actually I only have a 93% chance of getting killed. I checked. It's estimated that there have been 100 billion humans so far, and currently 7 billion humans alive. Until the last human dies, life doesn't have a 100% mortality rate. Isn't math fun?

Realistically though, I know one day I'm going to die, and I'm OK with that. Not that it would change anything if I wasn't. At the end of the road, I'll have been much happier having lived an awesome life (And quite possibly a longer one, too) than I would have been if I'd sat around in my apartment in my underwear playing video games for the entire time.

Everyone I've met who I've mentioned I skydive to has said "Ooh, that's always been on my bucket list!" One of them was a DBA who was a co-worker of mine until he fell off a ladder at his house and died. You'd be surprised at how many people that happens to. You know what's on my bucket list? A week of wingsuit flying over Hawaii. Once I'm reasonably comfortable flying the wingsuit, I'm going to go do that.

I'm trying to teach myself how to set things on fire with my mind. Hey... is it hot in here?

[brodg 0]

ghost47

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Yes, you're right bro.. Lol i was so sure of my numbers

Here's the method I've always used:

If you have a 1% chance of dying, that means you have a 99% chance of living.

So what are the odds of living after one jump? 99%. Two jumps? 99% * 99%. Three jumps? 99% * 99% * 99%. Etc. After 100 jumps you'll get 36.6% chance of living. That means, after 100 jumps, you have a 63.4% chance of dying.

That's of course assuming that you have a 1% chance of dying.

If, instead, you have a 0.001% chance of dying each jump (1 out of 100,000), then you have a 99.999% chance of living. Over 10,000 jumps, you get 90.48% chance of living. Which means 9.52% chance of dying.

Disclaimer: I haven't taken a math class, or significantly used math in my life, for close to 20 years. So I could be wrong.

ETA: However, once you get to the 9,999 jump, your odds of dying on Jump 10,000 would still be 0.001%. As would be true with any other jump you do.

Exactly! I just read the same here http://math.stackexchange.com/questions/227177/what-is-the-probability-of-an-independent-event-occurring-after-repeated-attempt Thanks for taking the time to clarify this bro.

Sorry I used the wrong procedure to calculate the probability (I took statistics way to long ago), but I think the concept still applies. Please correct me if I'm wrong but the numbers should be then:
*Probability of dying in one jump 0.00075%, so probability of living is 99.99925%
*Probability of not dying in 10.000 jumps is (0.9999925)^10.000 = 92.7%
*Probability of dying in 10.000 jumps is 7.3%

[Woofie 0]

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I assumed an active jumper does around 10.000 jumps throughout his life.

You assume WAY wrong. There's probably less than 25 people in America who have ever reached that many jumps. The average jumper probably never even gets to 1,000 in a lifetime. Just look at the award numbers in the back of Parachutist magazine. Compare the A license numbers to the 1,000 jump and 10,000 jump wings numbers.

What's your definition of "safe"?

If you can die doing it, it's not safe?
If the odds of dying are x, it's not safe?
What's your value for x?

[Remster 24]

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There's probably less than 25 people in America who have ever reached that many jumps.

You're right, 10k is not representative. But I would say there are way more than 25 jumper with 10k jumps in the US.

But, again, if you (the OP) are trying to convince yourself that skydiving is safe using statistics, you 're not getting it.

Adding skydiving as a regular activity significantly increases the risks your take. Deluding yourself that it's safe only makes it more dangerous for you, and me, so please get it.

Remster

[Arvoitus 1]

The statistics are entirely irrelevant.

You can die skydiving. If that is not acceptable then don't do it. If a student (tandem/SL) ask me whats the worst that can happen to them, I'll them that they can die. If they can't deal with that then they shouldn't be jumping.

Your rights end where my feelings begin.

[GLIDEANGLE 1]

I would argue that no matter how well you do the stats on the fatalities.... you will still VASTLY underestimate the real risk because you omit injuries.

Injury is common in skydiving and ranges from a bruise requiring an ice pack, to quadriplegia requiring an electric wheelchair and a ventilator! To ignore injury is to ignore a HUGE part of the risk that we face.

The choices we make have consequences, for us & for others!

[brodg 0]

Remster

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There's probably less than 25 people in America who have ever reached that many jumps.

You're right, 10k is not representative. But I would say there are way more than 25 jumper with 10k jumps in the US.

But, again, if you (the OP) are trying to convince yourself that skydiving is safe using statistics, you 're not getting it.

Adding skydiving as a regular activity significantly increases the risks your take. Deluding yourself that it's safe only makes it more dangerous for you, and me, so please get it.

Mmm I don't why do you assume I'm trying to convince myself skydiving is safe. If you read my post you'll see that in fact I stated just the opposite: skydiving needs to be perceived as a dangerous activity in order to try and make it safer.

[brodg 0]

GLIDEANGLE

I would argue that no matter how well you do the stats on the fatalities.... you will still VASTLY underestimate the real risk because you omit injuries.

Injury is common in skydiving and ranges from a bruise requiring an ice pack, to quadriplegia requiring an electric wheelchair and a ventilator! To ignore injury is to ignore a HUGE part of the risk that we face.

Agree!