Jumping out of Airplanes

Eddy Ardonne is an avid skydiver. He is currently an assistant professor at NORDITA in Stockholm where I am visiting this month, and he frequently offers to take people skydiving if they so happen to be interested. Smitha Vishveshwara*, who was once Eddy’s officemate, made a jump a few years back and loved it. My colleague from Ireland, Jiri Vala, was absolutely determined to try jumping this week and encouraged me to go too.

Now, to begin with, I’m a guy who doesn’t even like to drive in a convertible because I don’t like that much wind in my face. Why on earth would I want 120 MPH of wind in my face? I’m also rather afraid of heights (yes, I know, I’ve rock climbed in the past, but I never like being near a cliff unless I’m in my harness and anchored in). But perhaps because I was completely terrified of the idea, I was also curious about it, so I started doing some homework to find out, just how dangerous is it?

Being a statistics geek, the first thing I found was that many of the statistics that you find on the web are totally bogus comparisons.

The best verified figure I could find is that in skydiving there is roughly a 1 in 100,000 chance that you will die on any given jump. It might be a bit lower for certain types of jumps, or certain jumpers, and a bit higher for others. But very roughly, this seems always to be the right number**.

But back to bogus statistics: Here’s a statistic that gets thrown around an awful lot:

“Each year about 30 people die skydiving in the United States, and that's out of over 2 million parachute jumps. Given the odds, you're better off skydiving than let’s say driving a car. Every year, over 40,000 people die in traffic accidents”

Similarly many websites state that

“you are more likely to die driving to the dropzone than during your jump”

I’m calling a loud foul on both of these: The fatality rate for driving a car in the US (and most of the western world) is roughly one fatality per 100 million miles driven. So a single jump has the same fatality rate as driving a car one thousand miles. Spending an hour making a single jump is over 100 times more dangerous than driving a car for the same hour. Perhaps it is surprising (even impressive) that jumping out of airplanes is not more dangerous than this, but still the statements being made on the web are clearly inaccurate. I’m not particularly afraid of driving a car for a thousand miles, so there is not really much good reason to be afraid of making a single jump. However, if you make it a habit of jumping out of airplanes, you have to accept that it can start to become a significant added risk.

While I was searching for more statistics on the matter, I found quite a few interesting things about skydiving injuries. One of the strangest facts is that for solo student jumpers (not jumping in a tandem) apparently women have over twice the fatality probability than men. No one seems to know why this is, but it is an established fact. There are some other interesting statistics regarding how many times a fatality occurs from a real splat (no parachute deployment), versus from other means such as mid air collisions, improper landing with proper chute deployment etc. It turns out that the real splats account for less than 30% of the fatalities.

Another interesting stat (which is harder to pin down from data available) is that non-lifethreatening minor injuries are apparently pretty common - the “injury requiring medical attention” rate is roughly 1 out of 1000 jumps. Most of these are minor sprains, breaks, and so forth. But a few are more serious. If you compare this to say, a few years of participating in any other sport, you would probably have a similar rate of minor injuries. (One should be warned however that certain medical insurers do not cover skydiving injuries whether or not they are minor).

Anyway, Jiri and Eddy did go jumping yesterday and they both came back in one piece. I didn’t go. It really came down to a decision of whether I wanted to spend most of a day preparing for a 60 second drop (which I didn’t’ think I would enjoy all that much anyway). I think the main attraction to the idea was just that I was a bit afraid of it.

Maybe when I’m visiting Stockholm next year I’ll think about it again.

*Congratulations to Smitha on her marriage last month.

**It appears that this number does not include the possibility that the small plane you are in crashes before you jump out of it. It is hard to get numbers on the added risk from plane crashes, but my best estimate is that it is unlikely to more than double the risk.