parachuting

Parachute use to prevent death and major trauma when jumping from aircraft: randomized controlled trial

This is a repost promoting content originally published elsewhere. See more things Dan's reposted.

by BMJ

…

Conclusion

Parachute use did not reduce death or major traumatic injury when jumping from aircraft in the first randomized evaluation of this intervention.

However, the trial was only able to enroll participants on small stationary aircraft on the ground, suggesting cautious extrapolation to high altitude jumps.

…

Yeh et al (BMJ)

As always, when the BMJ publish a less-serious paper, it’s knock-your-socks-off funny. In this one, a randomised trial to determine whether or not parachutes are effective (compared to a placebo in the form of an empty backpack) at preventing death resulting from falling from an aircraft, when used by untrained participants, didn’t get many volunteer participants (funny, that!) until the experiment was adapted to involve only a leap from a stationary, grounded aircraft with an average jump height of 0.6 metres.

Silly though this paper is, its authors raise a valid point in the blog post accompanying their paper:

That no one would ever jump out of an aeroplane without a parachute has often been used to argue that randomising people to either a potentially life saving medical intervention or a control would be inappropriate, and that the efficacy of such an intervention should be discerned from clinical judgment alone. We disagree, for the most part. We believe that randomisation is critical to evaluating the benefits and harms of the vast majority of modern therapies, most of which are unlikely to be nearly as effective at achieving their end goal as parachutes are at preventing injury among people jumping from aircraft.

However, RCTs are vulnerable to pre-existing beliefs about standard of care, whether or not these beliefs are justified. Our attempts to recruit in-flight passengers to our ambitious trial were first met with quizzical looks and incredulity, predictably followed by a firm, “No, I would not jump without a parachute.” For the majority of the screened population of the PARACHUTE trial, there was no equipoise—parachutes are the prevailing standard of care. And we concur.

But what if we provided assurances that the planes were stationary and on the ground, and that the jump would be just a couple of feet? It was at this point that our study took off. We set out in two groups, one at Katama Airfield on Martha’s Vineyard and the other at the Yankee Air Museum in Ann Arbor. One by one, our study subjects jumped from either a small biplane or a helicopter, randomised to either a backpack equipped with a parachute or a look-a-like control. As promised, both aircraft were parked safely on terra firma. The matchup was, unsurprisingly, a draw, with no injuries in either group. In the first ever RCT of parachutes, the topline conclusion was clear: parachutes did not reduce death or major traumatic injury among people jumping from aircraft.

But topline results from RCTs often fail to reveal the full story. We conducted the PARACHUTE trial to illustrate the perils of interpreting trials outside of context. When strong beliefs about the standard of care exist in the community, often only low risk patients are enrolled in a trial, which can unsalvageably bias the results, akin to jumping from an aircraft without a parachute. Assuming that the findings of such a trial are generalisable to the broader population may produce disastrous consequences.

Using humour to kickstart serious conversations and to provide an alternative way of looking at important research issues is admirable in itself.

Penguins And Parachutes And Bears, Oh My!

I had a particularly strange dream last night. I’ll relate:

[some bits at an airport that I don’t remember]. Claire and I boarded an aeroplane. It was somewhat unusual as a ‘plane in that it seemed to be carrying cars, a bit like short-run passenger ferries or the channel tunnel. In addition, each car’s “space” had tall hospital-like curtains that could be pulled around it in a square to isolate it from those around it, providing some kind of privacy.

After having looked around the rest of the ‘plane, I returned to Claire’s car and looked out of the window, and saw that this lead on to what initially looked like more storage for cars (like the segment we were in), but later appeared to be hung under the wing (yes, out in the open). No cars on it, though. Thinking this was strange, I tried to open the window. It turned out we’d already taken off, and the air pressure difference, coupled with several hundred mph speeds, pulled Claire and I from the aircraft and started us plummeting.

A few moments of lucidity (which isn’t at all uncommon in my dreams) later I was able to deploy a parachute, as was Claire, and we sailed through the clouds and circled while we attempted to work out where we were. As it turns out, we were over the edges of Antarctica, and with some effort, we were able to maneuver our ‘chutes such that we landed (roughly, in high winds) on the shores, rather than in the water!

For some reason this dream had been influenced more by Disney than by actual geography or biology, because Antarctica was populated not only by several varieties of penguin, but also by polar bears. Some of these polar bears were able to talk… through the medium of visible “subtitles” and sign language… and one of them was kind enough to tell us about a research station nearby that he was “able to get in to”, and we were relieved that we would not have to freeze to death. At the research station, the friendly polar bear demonstrated how to climb up to a window, and helped me to do so too. I prized open the window and climbed inside while a huge crowd of the animals (mostly penguins) stood and watched.

As I was doing this and Claire was beginning to climb up, too, three humans with guns appeared on the horizon and began shooting at us. Claire hid among the penguins and I took refuge in the research station, but it turned out that the shooters had keys and they came in and found me, and, soon after, found Claire. They originally planned to kill and eat us, but I persuaded them not to by offering them my services as a landmine disposal expert (landmines, it seems, are a significant problem in the Antarctica). I’d lied – I wasn’t by any stretch an “expert”, but this didn’t seem to be such a problem as, while I was scavenging the supplies at the station for tools to use in finding and disarming landmines, my alarm clock went off and I woke up.

Just thought I’d share it with you all on account of it being so weird. Right: now I need to step out of the office to deliver Claire’s cashcard to her, which seems to have been left in my wallet, and then I can get on with some work!

One Thousand, Two Thousand, Three Thousand… Check Canopy!

Wow: a most memorable weekend. As you’ll remember, I spent the last weekend on a crash-course in parachuting in Lancashire. Having spent plenty of time in light aircraft or coasting around in a paraglider, I thought I had it sized: but it turned out to be even more spectacular (and scary) than I could have possibly predicted.

Saturday consisted of an exhausting seven hours or so of training: standing around in a field, doing such activities as demonstrating that we can arch our backs into the “stable position” and shouting “One thousand, two thousand, three thousand… check canopy!”, only to have some instructor shout “Malfunction!” and therefore have to go through our emergency process (“Look, locate, peel, pull, punch, arch!”) for the seventy-somethingth time… or lying on our bellies on overgrown skateboards, wiggling our bodies into strange contortions in order to simulate airflow (somewhat reminiscent of the idea of learning to swim by lying on a bench and practising strokes – little real value)… or clambering into a mock-up wooden aircraft (imagination required), climbing out onto the wing, and preparing to jump… or hanging in suspended harnesses, fumbling with the controls of make-believe parachutes…

I made my first jump on Saturday, early in the evening. Despite having been cool as a cucumber for the entire training process, I was very apprehensive by now. But this apprehension drifted gently away to be replaced with blind panic the moment we’d spiralled up to 3500 feet and the instructor opened the door, filling our faces with a 50mph wind. The plane was a small four-seater single-screw affair, with all but the pilot’s seat surgically removed so as to squeeze five parachutists (four students and an instructor, in this case) at a time into it, kneeling down and getting pins and needles in their feet. The instructor tapped the pilot on the shoulder: “Cut,” he shouted, and the pilot obliged, cutting engine power to a fraction and causing the plane to lurch downwards in a stomach-gulping manner. Before I knew it, it was my turn to jump.

“Feet out!” shouted the instructor, unsympathetically, slapping my on the shoulder and making a last check of my static line (the device that automatically deploys your parachute – essentially a long nylon strap attaching your ripcord to the pilot’s seat). I knew the drill by heart, having practised it to death on the ground: I grasped each side of the aeroplane’s door and put my right foot out onto the step. Then, that secure (considering the head wind), I reached out with my left hand and held the wing support beam. Then my right hand. Then, finally, I moved my left foot out and precariously swapped it with my right, leaving my right dangling above a 3500 foot hole. I couldn’t help but look down, and see fields stretching out, little cars moving along the roads, and occasional stray clouds meandering by. I looked back into the plane to signify my readiness…

“Go!” shouted the instructor. I let go.

At that moment, I forgot everything that I had spent so long learning. For some time to come, I was unable to remember the four seconds that followed. I was later to learn (and, later still, to remember) that I let go gracefully, but then – instead of forming the stable ‘arch’ position (important, as it keeps your back facing ‘up’, allowing your parachute to deploy correctly) – I put my hands by my sides, causing me to fall head-first until my ‘chute deployed. I remembered hanging onto the wing, and I remembered my parachute opening, but the rest was completely missing for the next half-hour.

During the three further jumps I performed on Sunday, there was no trace of the fear that had gripped me during the initial phases of my first: and, in fact, I was able to get the hang of assuming the correct position and landing without crippling myself… moreover, I’m now qualified to a level at which I’m permitted to begin DRCP (Dummy Rip-Cord Pull) jumps, in which I would leap from a plane and pull what is effectively a glorified handkerchief from the back of my backpack, symbolising the correct pulling of a rip-cord. Doing this will eventually allow me to do a free-fall, and is a progressive stage towards certification as a skydiver. Which is nice.

I loved it. Everybody in a fit state should do this sometime. Wonderful.

1000… 2000… 3000… Check Canopy! (Claire’s take)

This is a repost promoting content originally published elsewhere. See more things Dan's reposted.

This repost was published in hindsight, on 11 March 2019.

Claire wrote:

Yesterday I spent about 8 hours watching Dan and his Dad learn how to parachute. They did their first jump at about 6pm. It was a very comprehensive course, and I think that I could probably have jumped out with them, had I the money. They are jumping more today, I am joining them for lunch with the rest of his family and if they are good they will both get to do free fall (previously they did static line – the plane pulls out your parachute as you fall).

I didn’t realise quite how many safety procedures went into a parachute. Not only is there a reserve chute, but it can be released by
a) you cutting away the main chute (pull the red thing)
b) you pulling the reserve rip cord
c) your altimeter reaching a set height above a certain speed

So, even if you are unconscious, and your main parachute hasn’t opened, you will float gently to an area within 100m of the dropzone (They drop you such that if you use reserve you would land in the right place without even steering.)

With that in mind I am going to sign myself up for the university’s skydiving club in September. Dan seemed to enjoy it and thinks I would too.