7 ms·

Effect of passenger position on crash injury risk in aircraft (2015) [pdf]

63 points by susam 2y ago

geiser 2y ago
Summary of results?
- passwordoops 2y ago
  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"
- deleted 2y ago
  [deleted]
- deleted 2y ago
  [deleted]
thomas-martin 2y ago
"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 2y ago
  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 2y ago
    Same, there's no way I can put my head down, in ordinary economy seats, and I'm only slightly above average tall.
  - RobLach 2y ago
    Your head goes against the back of the seat in front of you then.
ccppurcell 2y ago
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 2y ago
  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 2y ago
    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 https://en.wikipedia.org/wiki/Chelyabinsk_meteor
  - jvanderbot 2y ago
    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.
glawre 2y ago
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_experiment https://en.m.wikipedia.org/wiki/2012_Boeing_727_crash_experi...
Qem 2y ago
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 2y ago
  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 2y ago
    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 2y ago
      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 2y ago
        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 2y ago
        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.
gumby 2y ago
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 2y ago
  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 2y ago
    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)
Aeolun 2y ago
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 2y ago
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 2y ago
  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 2y ago
  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 2y ago
    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 2y ago
  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 2y ago
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 2y ago
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 2y ago
  They should simply add the (expensive) option to buy a parachute that you may take home if unused.
  - simonswords82 2y ago
    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.
    - deleted 2y ago
      [deleted]
    - qup 2y ago
      I'll take my chances
- gravescale 2y ago
  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.
  - czl 2y ago
    Speak loudly to your travel companion during boarding: “Glad we got our seats far away from the crumple zone in the front.”
- tengbretson 2y ago
janfoeh 2y ago
In a crashing plane, the best position is in front of the plane. There, at least the drinks trolley comes by one more time.
lofaszvanitt 2y ago
Wouldn't it be easier that the whole part which holds the seats would be modular. So you get in your seat and the whole seat part with 300 or so seats is pushed into the plane on a rail. Fastened with whatever at X points and the plane is ready to go. So in a case of accident it can be jettisoned from the main fuselage, and it would land with a parachute without anyone getting injured.

63 points by susam 2y ago

geiser 2y ago

Summary of results?

passwordoops 2y ago
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"
deleted 2y ago
[deleted]
deleted 2y ago
[deleted]

thomas-martin 2y ago

"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 2y ago
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 2y ago
  Same, there's no way I can put my head down, in ordinary economy seats, and I'm only slightly above average tall.
- RobLach 2y ago
  Your head goes against the back of the seat in front of you then.

ccppurcell 2y ago

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 2y ago
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 2y ago
  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 https://en.wikipedia.org/wiki/Chelyabinsk_meteor
- jvanderbot 2y ago
  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.

glawre 2y ago

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_experiment https://en.m.wikipedia.org/wiki/2012_Boeing_727_crash_experi...

Qem 2y ago

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 2y ago
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 2y ago
  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 2y ago
    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 2y ago
      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 2y ago
        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.

gumby 2y ago

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 2y ago
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 2y ago
  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)

Aeolun 2y ago

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 2y ago

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 2y ago
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 2y ago
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 2y ago
  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 2y ago
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 2y ago

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 2y ago

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 2y ago
They should simply add the (expensive) option to buy a parachute that you may take home if unused.
- simonswords82 2y ago
  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.
  - deleted 2y ago
    [deleted]
  - qup 2y ago
    I'll take my chances
gravescale 2y ago
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.
- czl 2y ago
  Speak loudly to your travel companion during boarding: “Glad we got our seats far away from the crumple zone in the front.”
tengbretson 2y ago

janfoeh 2y ago

In a crashing plane, the best position is in front of the plane. There, at least the drinks trolley comes by one more time.

lofaszvanitt 2y ago

Wouldn't it be easier that the whole part which holds the seats would be modular. So you get in your seat and the whole seat part with 300 or so seats is pushed into the plane on a rail. Fastened with whatever at X points and the plane is ready to go. So in a case of accident it can be jettisoned from the main fuselage, and it would land with a parachute without anyone getting injured.