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Imagine that the pilots on a jet aircraft determine that it will crash. Consider what would happen if the design of the craft allowed it to:

  • Break into four pieces
  • Each piece is pressurized independently
  • Each piece is attached to large parachutes, similar to how they bring down Soyuz or other space crafts returning to Earth

Would that not work so that passenger jets are brought down safely instead of crashing?

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    $\begingroup$ Hello Corey, welcome to aviation.SE. You certainly have a creative mind, I am not so sure the idea is realistic. Aviation is somewhat weight-critical so this seems an expensive design change don't you think? $\endgroup$ – DeltaLima Oct 20 '14 at 21:51
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    $\begingroup$ Although I can see why this seems a silly question and is being down voted, I'm up voting due to the fact this has clearly been thought about and isn't just a random thought. The fact it's not practical doesn't mean it isn't worth asking $\endgroup$ – Jon Story Oct 20 '14 at 23:41
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    $\begingroup$ Random thoughts are awesome. Like "I wonder if I was racing along at the speed of light, could I reach out to a light beam beside me and touch it?" $\endgroup$ – Mikey Mouse Oct 21 '14 at 8:45
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    $\begingroup$ This is a valid question that I have heard asked many, many times. For those posting on this site the answer is obvious (weight, and go name any particular incident in which it would have helped) but for the naive public it seems like a logical aviation accessory. $\endgroup$ – dotancohen Oct 21 '14 at 10:08
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    $\begingroup$ @Ajedi32 It's already been asked an answered 100 years ago, I just wanted to use it as an example of why Random thoughts shouldn't be discouraged. $\endgroup$ – Mikey Mouse Oct 21 '14 at 14:02

11 Answers 11

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wouldnt that work for keeping a majority of passenger jets from crashing?

The majority of passenger jets don't crash.

Designing an aircraft like that would incur very substantial weight penalties. The Space Shuttle booster rocket parachutes weight 990kg, each (it needs 3) plus 550 kg for the drogue chute needed to pull out the main canopies. Plus another to pull out the 550kg drogue. Where are you going to put that much nylon?

Then there's regular maintenance of stuff that large and heavy - you will need an entire empty hangar to repack things along with a crew and a crane.

Also consider how you are going to break up a commercial airliner in an orderly manner. It would have to be designed for it and lined with explosives. That's going to be really popular.

Finally, parachutes need time to work. Large parachutes need considerable time. So this whole process only helps if there's a problem in cruise flight, and that's the phase with the lowest accident rate. Parachutes below 1000 feet are just excess weight.

Semi-related Addendum: After Challenger went boom the Space Shuttles were fitted with a crew escape system. It was intended to allow the crew to exit when the craft was under control but unable to reach a survivable landing site. Re-read that carefully: when the craft was under control. The crew exits at reasonable altitudes and the Shuttle crashes under remote control.

Parachutes simply haven't been a viable option for commercial air transportation since the DC-3 era.

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    $\begingroup$ In addition to the chutes there's also the substantial weight penalty of three separate sections of the fuselage with independent pressurization (or at least pressure retention): Pressure bulkheads are extraordinarily heavy. Pressure doors would have to be installed as well, and kept closed during flight (there goes food/beverage service), automatically closed in the event of separation (more weight!), or each section would need separate boarding and dedicated cabin crew (more money!). $\endgroup$ – voretaq7 Oct 20 '14 at 21:40
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    $\begingroup$ nice answer, I retracted my close vote and now hope you will be the first to get the reversal badge :-) $\endgroup$ – DeltaLima Oct 20 '14 at 21:51
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    $\begingroup$ Much stronger. I've been under 26-foot personnel parachutes when they open. It's not pleasant. $\endgroup$ – paul Oct 21 '14 at 13:46
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    $\begingroup$ You forgot the most important part - the passengers themselves would have to be strapped in and probably using something more than a lap belt considering the force of impact when the whole chunk is separated, the pyros fire to launch the chute, and then the force when the chutes finally deploy. $\endgroup$ – Burhan Khalid Oct 22 '14 at 8:35
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    $\begingroup$ "The majority of passenger jets don't crash." LOL!! Talk about an understatement. :-) Brilliant opening to this answer. $\endgroup$ – T.J. Crowder Oct 26 '14 at 11:31
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Paul's answer covers the main points (difficulty, expense, weight); I want to flesh out the rarity of use aspect.

As Paul says, most accidents happen during take-off and landing, when the system is useless because the parachutes wouldn't have enough altitude to deploy. The only time you'd be able to use this system would be if you were flying at a decent altitude and you knew in advance that the plane was going to crash. This almost never happens. Perhaps parachuting to earth would be a better option than trying to ditch a plane on water, especially over the ocean, but ditchings are very rare. Otherwise, unless there's been some mechanical failure that makes the plane uncontrollable, an emergency landing is probably going to be a better bet, even if all your engines are out and you have to glide – and a large passenger plane can glide for 20–25 minutes from altitude. In most circumstances, an intact plane can fly a decent distance and it would be very, very dangerous to turn any kind of flyable plane into a collection of free-falling components.

Indeed, the proposed system would be useful in such a tiny fraction of air accidents that you'd probably find it causing more deaths than it prevented. You're talking about fitting tens of thousands of planes with probably hundreds of explosive charges each. How many maintenance workers are going to be killed by how many accidental detonations? How many times is it going to fire accidentally in mid-air due to, say, a small cabin fire in just the wrong place or a lightning strike?

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    $\begingroup$ Some numbers you may want to add: an average plane (say a 747) can glide for about 93 miles from it's cruising height of 33k feet without any engines. $\endgroup$ – user2813274 Oct 21 '14 at 20:35
  • $\begingroup$ Part of what I was worried about was mis-firing of deployment. At a few million flights/year, there's bound to be a few airliners landing in someones backyard. $\endgroup$ – CoderTao Oct 22 '14 at 8:26
  • $\begingroup$ The take-off and landing crash scenario could be solved with a giant air-bag deployed under the aircraft by a cockpit button just before impact. A bit like a stunt crash-mat. Or hundreds or thousands of smaller ones, arranged in layers. I'm sure all the same weight caveats apply but I reckon it might get used more often than parachutes. Just a random crazy thought inspired by the original question. $\endgroup$ – Ed Randall Oct 22 '14 at 10:03
  • $\begingroup$ @EdRandall The (im)plausibility of that idea is a separate question. $\endgroup$ – David Richerby Oct 22 '14 at 10:09
  • $\begingroup$ Even in small aircraft, would there be any at-altitude problems that would necessitate parachute deployment that would be anywhere near as common as pilot incapacitation or freak loss of visibility--both issues that would be essentially irrelevant in an IFR-equipped airplane with a copilot? In a single-pilot aircraft which is not equipped for IFR, I would think a parachute system would serve mainly to guard against problems that are simply irrelevant in larger or commercial aircraft. $\endgroup$ – supercat Mar 12 '16 at 17:51
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I want to comment on the 'break apart into 4 sections' comment.

If your 4 parts were two wings, tail and the pressurized portion, thus reducing the weight that needed to be lowered safely (and removing some of the problems that Paul pointed out), you still have one major problem:

You've just designed a plane that has a way to specifically remove its wings in flight. This would be a terrorists's dream ... no need to bring their own explosives if they can hack into the control systems (don't even need to disable the parachute deployment, if you can get it to trigger when the plane's low enough, like while it's coming in for a landing ... or on takeoff, so it throws lots of fuel at the same time)

...

but I will mention that there do exist whole-plane parachutes, but they're for much, much smaller planes. (and they claim they only need 270' as they're rocket-deployed, so no drogue chute needed)

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  • $\begingroup$ This was my first thought and I did not even think of the issues everyone else is concentrating on. If we are thinking outside the box why cant we pack a small ultralight aircraft in our airplane. $\endgroup$ – emory Oct 21 '14 at 14:22
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    $\begingroup$ @emory How are you going to save a few hundred passengers with one small ultralight aircraft? $\endgroup$ – David Richerby Oct 21 '14 at 16:53
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    $\begingroup$ @DavidRicherby By taking multiple trips, of course. $\endgroup$ – Ghillie Dhu Oct 22 '14 at 5:57
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    $\begingroup$ Yes, it's a joke. $\endgroup$ – Ghillie Dhu Oct 22 '14 at 14:08
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    $\begingroup$ @HenningMakholm You have 20-25 minutes max before the failed plane hits the ground and a few hundred passengers to evacuate. If you your rescue plane holds a few people, it's going to take about 100 round trips to empty the plane. That's a round trip every 15-20 seconds. $\endgroup$ – David Richerby Oct 22 '14 at 17:24
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It's been done, but it was a major engineering feat just to do it with a four-person crew capsule. Ejecting sections of the passenger compartment of a commercial airliner would be even more difficult. As others have noted, it would significantly increase the cost and complexity of the aircraft and decrease its payload for very little improvement in safety.

Here is footage of the B-1b Lancer crew capsule.

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  • $\begingroup$ Isn't that a B-1a? The crew capsule design was replaced by ejection seats on the B-1b. $\endgroup$ – MSalters May 28 '15 at 13:18
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Parachute rescue system is available on smaller airplane, like Pipistrel Panthera, and latest Cirrus SR22/SR22T. Your scenario looks nice, but probably not practical enough to be installed on larger aircraft.

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    $\begingroup$ Hello Spidol Pulpen, welcome to Aviation.SE! Indeed parachute systems exist for smaller aircraft but not for larger aircraft. Could you please expand your answer and explain why it is not a practical solution for large aircraft. That would improve the quality of your answer. $\endgroup$ – DeltaLima Oct 23 '14 at 14:30
  • $\begingroup$ Also note that Cirrus aircraft since their very beginning have included parachutes. It's not restricted to the "latest" ones. $\endgroup$ – Jerry Coffin Oct 23 '14 at 15:46
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Any time the question is "why don't we have...", the answer is almost certainly in the trade-off between weight, maintenance cost, fuel cost, & utility. If it weighs a lot, needs maintenance, burns fuel, and will only be useful once a decade, then it just is not productive.

Putting a complex break-apart & parachute system on a plane will be heavy, meaning fewer passengers, or less fuel or cargo on board. All that extra weight has to be flown around, requiring fuel. They would need regular maintenance checks, which is another cost. And they would only be useful very, very infrequently (on most planes, it would never be used).

So it is just impossible to justify adding new equipment for a once-in-a-lifetime scenario, which can be better managed with good maintenance, good training, and good planning.

This same line of reasoning goes for "why don't more airplanes have rocket thrusters", "why don't planes have anti-missile systems", "why don't planes have airbags", and many other random items.

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Cost. That's it. Human life does have a cost associated with it. Its ugly to think about, but of course we have the technology to do something like this. Extra parachute systems would weigh more- and that dead weight has a cost in gallons of jet A, maintenance, life cycle and all the other things that go on the other side of the balance sheet. The aviation manufacturers build the planes their customers want- and their customers don't want to pay for the additional product maintenance life cycle cost of an extra couple tons of safety equipment.

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I forget which incident triggered it, but I recall some years ago that an inventor and his invention (for which he sought a patent), proposed to do almost exactly this, and was featured on a news story. The inventor felt that he was being brushed off for no good reason.

However, then as now, it's an unfeasible idea for numerous reasons including cost, weight, reliability, and insignificant or non-existent window of opportunity for effective use.

Consider: in exactly what sort of scenario could such a system actually offer a favorable outcome? How would it be determined that activation of the system is the correct action? If so, what preparation within the cabin would be needed pre-activation?

Bad things happen very rarely, extremely rarely at altitude (where any sort of parachute system would have a chance of deploying effectively) and happen without warning. By the time the emergency is recognized, it may be too late to push the button on such a system.

Another point: it is always better all around to prevent an emergency from ever occurring than it is to develop systems to be activated in response, especially when the response is as complex and expensive as a break-apart and parachute system.

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I've had a few chats within the business on this subject in light Ballistic Recovery Systems airframe parachutes developed for light, single engine aircraft. The consensus seems to be 1) weight - heavy equipment uses up useful load 2) added cost to buy and maintain 3) not necessary due to the redundancy in multi-engine aircraft 4) as earlier pointed out, most accidents happen during t/o or ldg where the a/c is too low for a successful deployment.

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An airliner travelling at over 800 kmph could never have a chute safely deploy in mid air... the design of such a thing wouldn't be possible. The strings, however synthetic, whether carbon fiber or whatever else would never hold to such pressure. Furthermore, the jolting force of have a chute deploy even at the minimum required flight speed of your average commercial jet, let's say 250mph would jolt passengers to the point of serious injury.

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    $\begingroup$ Apollo and other spacecraft managed it. The trick is to use staged parachutes, and possibly staged opening of parachutes. $\endgroup$ – Mark May 28 '15 at 22:47
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The bottom line for most operators is that modern airplanes simply don't crash. In the West, the probability is just about zero, so no emergency devices like this are needed.

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  • $\begingroup$ Are you aware of any stat or just create this account to try to be funny? $\endgroup$ – vasin1987 Jan 20 '15 at 10:12
  • $\begingroup$ @vasin1987, the last fatal crash of a US airliner was in late 2001. $\endgroup$ – Mark Jan 20 '15 at 11:08
  • $\begingroup$ @mark thanks for info. Implying West is more safe is too broad. Remember AF447? There are a lot of East airlines with great reputation. Try SQ or CX. By the way if you consider frieghter as well, the revent one is UPS1354 in 2013. $\endgroup$ – vasin1987 Jan 20 '15 at 12:54
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    $\begingroup$ If you're not familiar with commercial aviation, you may feel justified in responding in an abusive manner. But that just speaks to your inner urge to be a public spectacle. Consider 2014 as an example: there were 18 fatal airliner crashes in places such as Nepal, Malaysia, Iran, Algeria, Ethiopia, Indonesia, etc and NONE (ZERO) in North or South America, or Europe. There is a reason for this, and it's nothing to do with a lack of parachutes or other irrelevant devices. Bring facts; it's no help to anyone here if you just pop off with irrelevant remarks. $\endgroup$ – RJ Burke Jan 20 '15 at 23:39

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