[HN Gopher] Effect of passenger position on crash injury risk in...
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Effect of passenger position on crash injury risk in aircraft
(2015) [pdf]
Author : susam
Score : 50 points
Date : 2024-06-14 09:20 UTC (13 hours ago)
(HTM) web link (www.tc.faa.gov)
(TXT) w3m dump (www.tc.faa.gov)
| geiser wrote:
| Summary of results?
| passwordoops wrote:
| The abstract is on the third page:
|
| "In the event of an accident, one action that an occupant can
| take to contribute to their survival is to assume an
| appropriate "brace-for-impact" position. This is an action in
| which a person pre-positions their body against whatever they
| are most likely to be thrown against, significantly reducing
| injuries sustained. Occupants in the US Airways flight 1549
| sustained shoulder injuries that they attributed to the brace
| position; therefore, the NTSB recommended that the position be
| re-evaluated. The Federal Aviation Administration investigated
| this by conducting a series of 17 sled impact tests, 15 with
| two rows of transport category forward facing passenger seats
| and two with a bulkhead configured to represent the types of
| seats currently in use. Head, neck, upper and lower leg injury
| risks were evaluated using an advanced test dummy and injury
| criteria from current FAA regulations, Federal Motor Vehicle
| Safety Standards, European auto safety regulations, and
| applicable research findings. The current brace position, head
| against the seat back with hands on top of the seat back, was
| only successful in reducing head injury risk for locked-out
| seat backs. However, for full break-over and energy absorbing
| seat backs, this position increased the severity of the head
| impact. There was, however, no evidence that the
| anthropomorphic test device interaction with any of the
| seatback types resulted in hyper- extension of the shoulder
| joint. Significant lower leg injury potential was not observed
| in this study, and therefore adopting lower leg injury criteria
| at this time does not appear to be a benefit. Even in the worst
| case test condition, the femur axial compressive force was
| below the regulatory limit, indicating that the femur
| compression criteria currently cited in FAA regulations is not
| likely to be exceeded in passenger seat dynamic qualification
| tests. To reduce detrimental interaction between the occupant's
| arms and the seatback, the current position was modified by
| placing the hands down by the lower legs instead of on the seat
| back. This alternate position was successful in significantly
| reducing head and neck injury risk for all of the seat back
| types evaluated. This research has led to the determination
| that as seat technology has evolved, the most effective brace
| position has as well, and the current positions recommended in
| AC 121- 24B may need some adjustment to provide an equivalent
| level of safety for all passenger seat back types"
| thomas-martin wrote:
| "To reduce detrimental interaction between the occupant's arms
| and the seatback, the current position was modified by placing
| the hands down by the lower legs instead of on the seat back.
| This alternate position was successful in significantly reducing
| head and neck injury risk for all of the seat back types
| evaluated."
| otikik wrote:
| I am done for in any case.
|
| Current airplane seats are set up too closely to fit my femurs.
| There's simply not enough space for me to put my head down,
| independently of where my arms go ;(
| Tor3 wrote:
| Same, there's no way I can put my head down, in ordinary
| economy seats, and I'm only slightly above average tall.
| RobLach wrote:
| Your head goes against the back of the seat in front of you
| then.
| ccppurcell wrote:
| Casual readers will want page 3 for a description of the
| different positions and page 17 for a discussion of the results.
| The tldr is that the best seems to be: head against the seat in
| front of you, arms down by the lower legs.
|
| The fact that any brace position won't help in a head on
| collision and the foolish inference that it is therefore at best
| pointless and at worst some kind of ghoulish conspiracy (to
| maintain dental records, to ensure quick deaths yada yada) is a
| real bugbear of mine. Same goes for the criticism of "hide under
| a table during a nuclear attack". With any catastrophe, there are
| unavoidable deaths from the initial impact and loads of avoidable
| deaths and injuries from falling debris, glass shards, smoke
| inhalation etc. These measures are about the latter.
| simonbarker87 wrote:
| I'm sure during history class we looked at an analysis of some
| kind around Japanese who survived the nuclear bombs. At a
| certain distance from the center being sat down below a window
| was enough to survive whereas stood up in the same location
| would be fatal. Said history class was 25 years ago though so
| might be in accurate or out of date.
| kqr wrote:
| There's also this:
|
| > A fourth-grade teacher in Chelyabinsk, Yulia Karbysheva,
| was hailed as a hero after saving 44 children from imploding
| window glass cuts. Despite not knowing the origin of the
| intense flash of light, Karbysheva thought it prudent to take
| precautionary measures by ordering her students to stay away
| from the room's windows and to perform a duck and cover
| maneuver and then to leave the building. Karbysheva, who
| remained standing, was seriously lacerated when the blast
| arrived and window glass severed a tendon in one of her arms
| and left thigh; none of her students, whom she ordered to
| hide under their desks, suffered cuts. The teacher was taken
| to a hospital which received 112 people that day. The
| majority of the patients were suffering from cuts.
|
| From https://en.wikipedia.org/wiki/Chelyabinsk_meteor
| jvanderbot wrote:
| Speaking of bugbears. I have been fairly horrified by nuclear
| war and have read a ton of stuff about it.
|
| If you aren't immediately killed by a fireball, or roasted by
| radiated heat, and are outside the "everything gets blown
| down" radius, it seems the major immediate danger is extreme
| winds from the blast. (Though radiated heat is also a line of
| sight effect)
|
| So it absolutely makes sense that you'd want to be in a
| position that prevents all kinds of glass and debris impact,
| let alone getting thrown yourself.
|
| My mental model is "instant tornado" and since I'm in the
| north, we all have basements to run to.
| Aeolun wrote:
| I love the 'instant tornado' image.
| glawre wrote:
| This reminds me of the "Plane Crash" documentary where a 727 was
| crashed into a desert in Mexico. Definitely worth a watch for any
| aviation enthusiasts:
| https://en.m.wikipedia.org/wiki/2012_Boeing_727_crash_experi...
| Qem wrote:
| I wish they had modelled the effects of installing the passenger
| seats facing backwards. Passengers have no need to see forward in
| a plane, different from pilots, and in the event of sudden
| deceleration the seat would help cushion the impact, what I
| believe would probably improve safety in most survivable crash
| scenarios.
| playingalong wrote:
| Wouldn't it make some people feel sick? Not sure if there's any
| science to back people preferring to sit forward facing in
| trains
| mathieuh wrote:
| Trains accelerate and decelerate relatively often compared to
| planes where you only really notice changes in velocity at
| take-off and landing so I don't think it would make a
| difference
| Tor3 wrote:
| Japanese limited express trains and the bullet train have
| very few stops (or none, depending), and the ride is very
| smooth.. still, my wife (Japanese) can't sit backwards-
| facing without getting sick. Not sure what causes this.
| Aeolun wrote:
| It would not surprise if there was something about human
| physiology that thinks it's unnatural to go backwards.
| Our eyes are in front of our head for a reason.
| Qem wrote:
| I don't know for sure, but is very common to see parents
| carrying children facing backwards in their arms, while
| walking, with no ill effects. No big deal.
| flemhans wrote:
| Tangentially related: The seats on Shinkansen trains can
| be rotated to adapt to the needs of the passengers.
| dredmorbius wrote:
| Many US commuter-rail trains also have reversible seats.
| The train crew generally orient these to be forward-
| facing for the direction of travel, possibly excepting
| the first seat in a car.
|
| (The trainsets reverse directions without being turned
| around themselves. Those using locomotives rather than
| electric traction operate in "pusher" mode for half their
| trips. There's an operator cab in the end car for such
| trips.)
| Qem wrote:
| A few seats could be left facing forward, for people who
| would feel sick, but backward facing probably should be
| default. It's hard to believe smashing your face against the
| hard back surface from the seat in front of you is better
| than being pushed hard against the soft cushion from your own
| seat. Also the load would be more evenly distributed across
| the whole body.
| BobaFloutist wrote:
| I thought about that, but then I realized that the
| acceleration is going to be (more or less) equal and opposite
| for take-off and landing, so it's more about which one you
| want first, no?
| jacktribe wrote:
| The angle of descent is of about 3 degrees, that's far less
| than the angle at which the aircraft is taking off. Thus
| the rear facing passengers would be facing down quite
| steeply on takeoff, and thus likely to vomit the airport
| lounge food they just had :)
| alamortsubite wrote:
| I think it would absolutely improve safety. Except for some
| very contrived scenarios, deceleration in a crash approaches
| infinity (mitigated only by the elasticity of the fuselage and
| whatever it impacts). Better to experience that spread out
| across a soft seat cushion than concentrated into an inelastic
| lap and shoulder belt.
|
| Unfortunately, the psyche of the average passenger can't handle
| riding backwards. I've never understood it. Remove visual
| stimuli and it's impossible to tell the difference. Maybe we
| just need to close the window shades on takeoff and landing?
| cyberax wrote:
| Belts are actually elastic. They just are not that easy to
| stretch, which is exactly what you want.
| abdullahkhalids wrote:
| Many trains have backward facing seats. It's not common for
| people to have a problem sitting in them, certainly a
| minority. And train windows are usually several times larger
| than plane windows.
| russdill wrote:
| There are some planes with a few backward facing seats. Takeoff
| is more comfortable in a forward facing seat
| dredmorbius wrote:
| Military troop transports frequently utilise rear-facing seats,
| and I suspect there's enough incident data to arrive at useful
| conclusions.
| gumby wrote:
| One of the great things of the last ~25 years is the small _n_ in
| regards to commercial aircraft fatalities. This report is dated
| 2015 but I wonder if it would be any different a decade later. In
| the prior 50 years, plane crashes were, maybe not _common_ , but
| something you'd read about every month or so.
|
| The only emergency landing I've been in where the crew briefed us
| on position and checked us was hands on the back of the seat in
| front. Luckily it wasn't a crash and the fire was quickly
| contained on the ground. Turned out the shoe removal was the most
| inconvenient but perhaps the most useful (evacuation slides
| worked, but then we were on hot tarmac without shoes).
|
| What astonished me the most was how everybody went along and
| didn't complain. This was almost 35 years ago --- I wonder if
| that would still be the case. These days I have seen pictures of
| people sliding down the evacuation slides with hand luggage!
| adrian_b wrote:
| I am not convinced about the wisdom of forbidding to take the
| hand luggage.
|
| It is true that there are many people who have a big and
| awkward hand luggage or who need a very long time to recover
| their luggage from overhead.
|
| There are also many other people who are able to recover their
| hand luggage from the overhead in less than a second and in
| much less time than most other passengers are able to just
| stand up.
|
| I do not see why such passengers should be penalized, even if
| they would certainly not slow down the evacuation. Losing the
| documents and data from the hand luggage may cause very serious
| problems that could need many months of work for solving and
| passing through many unpleasant experiences until then.
|
| The only argument against this that is correct, is that like in
| every other domain people would self-assess their own abilities
| too optimistically, so even those who are slow would believe
| that they can retrieve their luggage fast enough to not hinder
| the evacuation, but then they would be proven wrong.
|
| Perhaps the passengers should pass a test of hand luggage
| retrieval speed, before the flight, in order to be pre-approved
| for keeping their hand luggage in the case of an emergency
| landing :-)
| stephen_g wrote:
| It's not safe to bring down the slide. Going down the slide
| at all dangerous, people break legs every now and then. But
| even worse, the person in front of you really doesn't want
| your hand luggage flying out of your grip and knocking them
| out (which can cause a lot of other problems)
| adrian_b wrote:
| That is true for a big case, but not for a backpack carried
| on the breast.
|
| I agree that the retrieval of any bulky hand luggage should
| be forbidden.
| tdullien wrote:
| Frankly, if in a rare life-or-death situation you care
| about your hand luggage, I'd recommend carefully
| reflecting on life choices and priorities.
| mpreda wrote:
| Here, take my hand luggage and go! I'll stay behind..
| lesuorac wrote:
| Eh, I think this is a don't throw the baby out with the
| bathwater scenario.
|
| You have way more time than you might expect after a
| plane crash. "Finally, [Captain] Sullenberger walked the
| cabin twice to confirm it was empty" [1]. If anybody had
| grabbed their hand luggage (especially from below their
| seat) they would've still had time to evacuate.
|
| [1]: https://en.wikipedia.org/wiki/US_Airways_Flight_1549
| #Ditchin...
| imranhou wrote:
| Ah I see you like to generalize. This plane was lucky
| that it didn't burst into flames as soon as everyone
| exited or worse yet while they were still exiting.
| sofixa wrote:
| > You have way more time than you might expect after a
| plane crash. "Finally, [Captain] Sullenberger walked the
| cabin twice to confirm it was empty" [1]. If anybody had
| grabbed their hand luggage (especially from below their
| seat) they would've still had time to evacuate.
|
| But if they had taken their backpack or suitcase, and had
| dropped it, they could have blocked other people; knocked
| other people out; broken someone's ankle making them
| harder to evacuate etc etc.
|
| And this was a calm evacuation. Imagine a fire, low
| visibility due to the smoke, the sense of urgency, and
| you trip on some dimwit's suitcase, pushing the people in
| front of you down, some of them hitting heads, then panic
| sets in, the path towards that emergency exit is blocked,
| etc etc etc.
|
| Leave your fucking luggage behind. If everything is fine,
| it will get to you afterwards. If the plane is on fire,
| you won't, but you'd also not kill people by not taking
| it.
| tdullien wrote:
| My question is: what could possibly be so important that
| you want to take it with you to have your hands full in
| an emergency potential life-or-death situation?
| lesuorac wrote:
| Uh, there's plenty of time to kill while you wait for the
| people ahead of you to deboard. Grabbing your phone isn't
| going to kill anybody.
|
| Hell, even when there isn't plenty of time to kill
| grabbing your phone isn't going to kill anybody. [1]
|
| You can phrase it as "important enough" all you want, but
| its really just why let an item to go waste
| unnecessarily.
|
| [1]: https://youtu.be/CtmxTj9pKqg
| toast0 wrote:
| Most phones aren't comparable to a bag, even a small bag.
|
| Yeah, probably put your phone in your pocket if it's
| accessible. Keep your wallet in your pocket. If your
| wallet doesn't fit in your pocket, at least grab your id
| and payment cards, if they announce a rough landing while
| on approach and you have time to prepare a bit.
| FabHK wrote:
| Different plane crashes are different.
|
| When a Sukhoi Superjet 100 crash landed in Moscow, a fire
| broke out and fewer than half of the 78 occupants managed
| to escape the plane on time.
|
| > Aeroflot claimed the evacuation took 55 seconds, though
| video evidence shows the slides still in use 70 seconds
| after their deployment. Passengers were seen carrying
| hand luggage out of the aircraft.
|
| And you think that you're competent to determine whether
| there is sufficient time or not after the plane just
| crashed? If I were sitting in the row behind you, I'd
| much prefer you didn't.
|
| https://en.wikipedia.org/wiki/Aeroflot_Flight_1492
| cyberax wrote:
| It absolutely is. You have not seen the evacuation slides
| in person, they are NOT the fun water slides that you
| have in amusement parks.
|
| You probably will lose grip on the backpack if you just
| carry it in your hands. And if you have straps behind
| your back, it's even worse because you can get tangled
| and delay others' evacuation.
| imranhou wrote:
| I'm sure that less than second added a hundred times over can
| save some lives, plus in a tighter situation, bags behinds
| your back or in your hand will take up additional space that
| could accommodate another human.
| adrian_b wrote:
| The seconds are not added, because the corresponding
| activities are concurrent.
|
| I am pretty sure that except for the people adjacent to the
| emergency exits, the others will have to wait their turn
| for a much longer time.
|
| A backpack carried on the breast would not occupy space in
| which another human could have stayed.
| imranhou wrote:
| There are multiple seats per row and only the first
| person of that row may benefit from the concurrency, as
| each person gets into the isle for that row they will add
| those seconds and that is sequential not concurrent. Also
| you likely haven't been in a trampling crowd situation,
| bag on a chest doesn't occupy zero space.
| lesuorac wrote:
| > A backpack carried on the breast would not occupy space
| in which another human could have stayed.
|
| An individual backpack might not displace an individual
| human but across ~300 passengers those 50 backpacks will
| displace people.
| efunnekol wrote:
| As someone who has spent a lot of time defining and
| enforcing processes (yay), it is far easier and more
| understandable to adopt a hard rule for this sort of
| thing. You don't want people to be debating whether or
| not their backpack is the acceptable size to include,
| while someone else's laptop case is not. Then you have
| someone saying that they are allowed to take their
| backpack, but it is in the overhead bin one row behind
| them, so could you just pass it to me...
|
| For life or death situations, you need to have short
| clear rules that are easy to follow.
|
| Remember, you will only actually lose your stuff if the
| plane is destroyed. If the plane is in the middle of
| being destroyed, just get out and be glad you are still
| alive!
| JumpCrisscross wrote:
| > _it is far easier and more understandable to adopt a
| hard rule_
|
| Looking at this thread, we might need to put into
| regulation that taking baggage during an emergency
| evacuation is criminally negligent. (If someone behind
| you dies, negligent homicide.)
| JumpCrisscross wrote:
| > _The seconds are not added, because the corresponding
| activities are concurrent_
|
| A passenger has practically zero information as to the
| seriousness of the crash. It could be a doozy. Or there
| could be a fuel leak waiting to ignite.
|
| > _backpack carried on the breast would not occupy space
| in which another human could have stayed_
|
| You're claiming given two lines of people, one wearing
| backpacks, the other not, that the latter cannot be
| compressed more than the former?
| pif wrote:
| The discriminant is the following question: what if everybody
| behaved like me?
| lostlogin wrote:
| > Perhaps the passengers should pass a test of hand luggage
| retrieval speed, before the flight, in order to be pre-
| approved
|
| Boarding.
|
| It's a shit show of people doing annoying stuff with their
| bags.
|
| The idea that you could have some who can take their bags and
| some who can't and that this would be acceptable to everyone
| is just not going to work. Combine this with the fact that a
| crisis alters people's abilities. Some may be injured, some
| may be shocked. Then some poor crew member has to police the
| bs behaviour that would result.
| dwighttk wrote:
| This is life and death... absolute rule is better then "use
| your judgement" because plenty of people are gonna say "this
| 10 minute process is definitely just taking 1 second"
| gumby wrote:
| For the case I wrote about, on one side of the plane the
| ground crew was spraying foam on the wing and engines;
| everybody had to exit on the other side. FAA wants the entire
| plane emptied in 90 seconds.
|
| In addition whatever you're carrying could injure you during
| decent (especially at the end - FAA is OK with people
| breaking ankles) or worse piece the chute. The crew came by
| and took everybody's shoes and stowed them in the overheads
| before they checked our brace positions. They also moved me
| and two other guys in our 20s into the exit row and ejected
| the three people already there.
|
| Our cabin could have been full of smoke, or worse (luckily,
| it was not at all like that) and so do you think they want to
| try to explain a decision tree to a bunch of panicked
| passengers?
| telesilla wrote:
| If you're really concerned about your valuables, wear them
| under your shirt, like a passport and card holder against
| pickpockets. If you're worried about losing data on your
| devices it's an easily solved problem to start backups today.
| I've had luck travelling this way against theft.
| tristanb wrote:
| I hope we don't travel on the same aircraft.
| Calavar wrote:
| > The only argument against this that is correct, is that
| like in every other domain people would self-assess their own
| abilities too optimistically, so even those who are slow
| would believe that they can retrieve their luggage fast
| enough to not hinder the evacuation, but then they would be
| proven wrong.
|
| This is they key. Not only overestimating their speed in
| taking down the luggage, but also other passengers
| overestimating how much time they have to safely get off the
| plane.
|
| Take Spantax Flight 995, for example. Almost everyone
| survived the initial crash landing, but dozens died from
| smoke inhalation. Most of those who died were seated in the
| rear of the plane, where there was traffic in the aisles due
| to one or two people grabbing luggage from the overhead bins.
| There is an account from a survivor from the rear of the
| plane who only managed to escape because he climbed over the
| seats to get around the traffic. Most other passengers in the
| area were content to wait, not realizing how quickly the
| smoke would spread and turn lethal.
| hgyjnbdet wrote:
| > Losing the documents and data from the hand luggage may
| cause very serious problems that could need many months of
| work for solving and passing through many unpleasant
| experiences until then.
|
| Rather go through the months of work solving problem and
| having unpleasant experiences than be dead.
|
| And you can be confident anyone holding me up in an emergency
| for mere documents and papers is going to experience
| immediate unpleasantness that they aren't going to solve.
| Aeolun wrote:
| They had 17 test variants but they thought it was too much effort
| to try multiple times?
|
| It sounds really interesting, but without multiple tries I'm not
| sure how much weight I can put on this.
| jalk wrote:
| I heard a story about a guy, who was one of the few survivors in
| a crash. His explanation was that he had his waist belt very
| tight. On his way out he saw a lot of people with severe
| abdominal injuries, caused by being flung into the slack belt.
| Does this sound plausible at all?
|
| EDIT: typo
| alamortsubite wrote:
| It would depend on the mechanics of the crash, but sure. Safety
| belts are inelastic, so any shock and subsequent deceleration
| experienced by the body at the end of the belt's slack will be
| absorbed by tissue and skeleton.
|
| This is also why climbers use "dynamic" (elastic) ropes (when
| climbing, not necessarily for rappelling). Even a very short
| fall on a static line could be fatal.
| chx wrote:
| This is extremely unlikely for several reasons.
|
| 1. There hasn't been a crash involving a commercial flight with
| few survivors in living memory. Either you get something like
| MH370 where everyone perishes or you get Asiana in SF which had
| three fatalities.
|
| 2. Absolutely baloney about the belt, the worst you can get is
| a bruise.
| filleduchaos wrote:
| Confidently asserting that there hasn't been a crash
| involving a commercial flight with few survivors in living
| memory and your examples are all post-2010 flights
| is...certainly something. There are plenty of people much
| older than 20-30 years still kicking.
|
| And you can get a _hell_ of a lot more than a bruise from a
| seatbelt due to the magnitude of the forces involved in a
| plane crash, especially one that [allegedly] killed almost
| everyone else. Seat belt syndrome is a well-known thing.
|
| The GP's story may or may not be true but your points for it
| being "extremely unlikely" don't hold water at all.
| garaetjjte wrote:
| This is called "submarining" and it's a factor in seat shape
| design. It's also one of the reasons why car seatbelts have
| pretensioners.
| imranhou wrote:
| From the summary, it is unclear if this study takes into account
| human behavior vs a dummy when the hands are on top of the front
| seat back. While a dummy may not hold the front seat with a
| tighter grasp with its hands, a human during impact may or may
| not change the outcome through either pushing the front seat out
| or pulling it backwards which can directly alter the outcome of
| the study.
| albert_e wrote:
| I initially assumed the title meant the location of your seat on
| the plane and thought:
|
| oh boy, that's one more thing that (1) passengers will
| irrationally fear about and spread hearsay about "safest" seats
| on a plane and (2) airlines will try to charge a premium for
| those safest seats :)
| mpreda wrote:
| They should simply add the (expensive) option to buy a
| parachute that you may take home if unused.
| simonswords82 wrote:
| You need to be trained to use a parachute. You also can't
| jump out at 35000ft doing nearly the speed of sound and
| expect to have a good time.
| gravescale wrote:
| Last I heard it was the back of the plane that was
| statistically safer. Most people still seem to want the front
| because it gets you off the plane faster and puts you at the
| front of the passport queue. Especially on larger planes going
| to places with lots of non-locals going through the slower
| manual channels.
| janfoeh wrote:
| In a crashing plane, the best position is in front of the plane.
| There, at least the drinks trolley comes by one more time.
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