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Comment by simplegeek | Hacker News Reader

Good question. Likewise, I've always wondered why don't they have parachutes in aeroplanes :(

The percentage of actual crashes in which a parachute would do anyone any good is likely vanishingly small.

You can't use them when too high up (not enough O2) or too low (not enough time to deploy). Most crashes take place on takeoff or landing.

Of the problems that do happen that would take you through a "jumpable" altitude, you can only make the jump if you 1) have time, 2) have enough airplane left to jump out of. If a big whole ripped in the plane while in flight at 30k feet, you are very likely already unconscious or dead.

There are other issues related to the fact that commercial airliners are not made to be jumped out of at speed. Its difficult or impossible to open their doors during flight (with good reason). Even if you could get them open, there may not be a jump trajectory from some doors that doesn't provide a personal introduction to wing or engine part. Also, you cannot jump and live from a plane going 300 knots. The plane would have to decelerate to near stall to make it safe and if its already crashing, maneuvering at the edge of performance is not likely.

Also, consider that professional and military jumpers are highly trained, in top physical shape, and the landing sites are carefully chosen to avoid injury. As a fun thought experiment, take Rosanne Bar, put her in a small canopy "emergency chute", and drop her, at random, over the Arizona desert. (She was on her way to Vegas, baby). Calculate survivability.

Chutes for everyone would be expensive, heavy and probably only be beneficial in single digit percentages (or even sub single) of all crashes. They would very likely cause more problems than they would solve.

i'm sorry but i just don't buy the 'chutes aren't worth it / wouldn't work' argument. i'm confident that in the next few decades we'll have better safety systems in planes, it will just take a few really smart engineers. people will still die in planes, sure, but in the cases where chutes or whatever will help, there will be huge benefits.

Strangely chutes on planes might be worth it, but maybe not like you think.

http://en.wikipedia.org/wiki/Ballistic_Recovery_Systems

This is an intriguing idea, has anybody heard of any research done for this regarding passenger airplanes?

Based on the article, I'm guessing large passenger jets are some time off. BRS is currently working on systems for very small business jets.

For this to be true everyone would have to wear one, and the plane would have to break open in mid-air. Obviously, structural integrity is an asset more often than a disadvantage. You won't be able to engineer this unless everyone sits in mini capsules and the plane like a ballistic missile with MIRV. The costs (in planes accidentally exploding over false positives and spewing out their encapsulated passengers) vastly outweigh the benefits.

There is a small aircraft manufacturer, Cirrus that puts a parachute recovery system right on the aircraft itself.

Notably, reviews have been mixed. http://en.wikipedia.org/wiki/Ballistic_Recovery_Systems

Cirrus, it should be noted has an below average crash rate compared to other aircraft in class. Clearly, the small total of 18 deployments compared to the crash rate leaves a lot of work to be done.

Nobody knows how to make a ballistic parachute that will handle a passenger jet, especially not a widebody A330.

Airplane doors CANNOT be opened in flight unless you depressurize the airplane first. Even then, it would probably be difficult. The only airliner (that I am aware of) that could have the rear stairs opened in flight was the 727, which was "fixed" after D.B. Cooper took that way out. (Odds are pretty good he didn't make it, either.)

http://en.wikipedia.org/wiki/Cooper_vane

There are a number of reasons. I will list some here:

1. Operational knowledge is lacking.

2. 300 people trying to jump from a plane through 2 3 foot doors will probably cause a crash alone.

3. Pointless at > FL 10. There is no oxygen up there.

4. It's also about -50C ish > FL 10. You would fall as a frozen popsicle.

5. Would add about 1000lbs of weight to the aircraft.

6. People floating around in the Atlantic isn't really an improvement.

7. 95% of all aircraft failures result in a safe landing. Only a small percentage result in crashes at the commercial aircraft level.

8. People hanging in trees all over the province of Alberta isn't really an improvement.

9. People landing in traffic in Denver isn't really an improvement.

I think you get the point. The answer is that parachutes are completely impractical for 90% of all aviation uses.

Because unless most passengers are actually trained in how to use them, it wouldn't do much good; plus, for most reasonably sized planes, there simply wouldn't be enough time for anyone to jump with a chute.

Probably because the majority of passengers are not trained to operate a parachute, attempting to jump out of a plane at 40,000 ft is likely to be lethal even with a parachute, and that having 200+ people orderly jump out of a plane with parachutes while the plane is crashing out of control is unlikely to work.

A more interesting question is why one is not permitted to bring a parachute on board at one's own expense, and why there are not even token provisions for enabling their use in a situation where they might be helpful.

Air travel phobia seems to be rooted in the lack of control experienced by the passenger - specifically, in the anticipation of utter helplessness in the event of a crash. A parachute would help with that, even if its role is largely ceremonial.

I suspect it's a practical concern if nothing else, having to do with mundane constraints like carry-on sizes. Also, as another practical matter, I highly doubt that the folks with severe air travel phobia would be even remotely trained to use a chute (which requires doing it, more than once!)

D.B. Cooper. Allowing people the means to parachute from airliners only enables hijacking as a means of escape from the law.

Then why not have garlands of frag grenades hanging on the ceiling as part of every bank's security system? Why should we enable bank robbers to escape from the law when hijackers cannot?

I'd prefer to fly on planes which aren't execution chambers for criminal and witness alike. The market refuses to provide me with this option, however.

"Then why not have garlands of frag grenades hanging on the ceiling as part of every bank's security system?"

Because that would have significant side effects. Since parachutes are pretty much useless on airliners anyway, no significant side effects from banning them.

Which airlines are you flying that seem to have ridiculously spacious cabins?

I don't understand why you're asking me that--I'm not the one arguing for parachutes.

Ah, I re-read your comment. Sorry, I thought you were saying that there was no side effect in allowing them on the plane, to which I was pointing out that space is a serious side effect.

lol, it's pre coffee reading that will do me in everytime.

>The market refuses to provide me with this option, however.

What are you talking about? The market already provides that option in several forms:

1. Learn to fly and fly yourself. 2. Rent a pilot and a plane and get to where you want to be.

You might not be able to afford those options, but they are there.

Parachute use at high altitudes means you have to either depressurize the entire cabin, or else create some sort of airlock which allows you to get into an unpressurized space so that you can open a door to the outside; which would add a large amount of weight and take up expensive space.

The reality is, that you are in fact utterly helpless in the event of a crash.

Assuming that there was a part of the plane that could open to create a viable jump platform (which there isn't in current designs), it would seem that the situations the plane has a problem, but it's stable enough that you and your 2-500 friends can get out your chute, read the instructions, put it on correctly, get to the exit point, and safely jump out and your plane has enough of a problem that you'd want to jump out are mutually exclusive.

Despite military usage of HALO and HAHO high altitude parachute techniques (25-30,000 ft) since the vietnam war, very few civilians have ever made the leap. Assuming you could actually get out of a pressurized cabin, you'd almost certainly blackout from hypoxia before you opened your chute and you'd turn into a popsicle from sub-zero temps.

HALO jumpers breathe pure oxygen onboard and jump with oxygen tanks. A single breathe during the transfer is enough to return your nitrogen levels to normal and cause blackout on egress. Any kind of medical condition, even anxiety or exhaustion can dramatically affect your susceptibility to hypoxia and normal clothes would not save you from frostbite.

By the way, 747's cruise at up to 40k altitude and 565mph. Jumping out is not a good idea.

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