Don’t seats that recline flat defeat the purpose of having seatbelts?Why don't airlines provide smoke hoods?Why do you have to keep your seat belt fastened after landing?Why were the TWA TriStar middle seats smaller than the aisle seats?Is there research being done on light aircraft safety that involves a comprehensive flight protection system that adresses all risks?Why aren't the passenger seats designed as jump seats (foldable) in commercial airlines?Could a golf ball damage an airliner?Why do airlines require passengers to return to their allocated seats for landing?What are the technical details of how airline seats are installed on an airliner?Where are the black triangle'd seats?Why don’t aircraft use run-flat tyres?

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Don’t seats that recline flat defeat the purpose of having seatbelts?


Why don't airlines provide smoke hoods?Why do you have to keep your seat belt fastened after landing?Why were the TWA TriStar middle seats smaller than the aisle seats?Is there research being done on light aircraft safety that involves a comprehensive flight protection system that adresses all risks?Why aren't the passenger seats designed as jump seats (foldable) in commercial airlines?Could a golf ball damage an airliner?Why do airlines require passengers to return to their allocated seats for landing?What are the technical details of how airline seats are installed on an airliner?Where are the black triangle'd seats?Why don’t aircraft use run-flat tyres?













1












$begingroup$


Virtually all first-class airline seats, and many to most business-class seats, recline all the way down, either as lie-flat seats (where the seat reclines to a 180º seatback-seatpan angle, but the fully-reclined seat is still tilted somewhat forwards relative to the cabin floor) or flat-bed seats (where the seat reclines to a truly flat surface that can also, as the name indicates, serve as a bed).



These seats are, of course, equipped with seatbelts, but I’m having great trouble seeing how even a tightly-fastened seatbelt would provide any protection to a flat-lying occupant, as any significant longitudinal force would cause the occupant of the seat to slide under the belt and out of the seat.12



Although these seats, like all airline passenger seats, are required to be locked in the fully-upright position except in cruise flight, this still leaves the occupants (especially those in flat-bed seats) vulnerable during the (sometimes quite long) portion of the flight when they are allowed to recline their seats to flatness; a moderate head-on (or tail-on, for that matter) gust would be enough to separate these occupants from their fully-reclined seats, as would any other event capable of suddenly increasing or decreasing an aircraft’s inertial speed too quickly for the “fasten seat belts” sign to provide any warning (not, as noted above, that fastening their seatbelts would actually provide any significant degree of protection to the occupants in question, but it could conceivably induce them to derecline their seats in preparation), such as a flight-control malfunction or evasive action to avoid a MAC (both of which produce large speed excursions secondary to rapid changes in attitude and altitude).



For that matter, even vertical accelerations with no longitudinal component would still be expected to injure flat-lying passengers more severely than those in an ordinary sitting position, for reasons illustrated below:



OUCH



Am I missing something?




1: This is known as submarining, and is a major problem with car seatbelts (even with seats that don’t recline at all), which are much harder to fasten tightly around the pelvis than aircraft seatbelts.



2: If the belt were fastened tightly enough to pin the occupant to the seat even under considerable longitudinal force, this would



  • be highly uncomfortable for the occupant, and

  • upon the application of significant longitudinal forces, drag across the occupant’s abdomen until catching on their ribcage, causing severe internal abdominal injuries plus likely breaking the bottom few ribs.









share|improve this question











$endgroup$











  • $begingroup$
    Can you format the first part of this so that it isn't a large wall of text?
    $endgroup$
    – Ron Beyer
    2 hours ago










  • $begingroup$
    I like your drawing.
    $endgroup$
    – vasin1987
    2 hours ago










  • $begingroup$
    Usually when the seatbelt sign goes on, especially if they ask the flight attendants to sit down, they'll ask people to bring the seat backs up. I've never heard of an instance of a "sudden" head wind or tail wind powerful enough to unseat passengers. Turbulence is a bigger issue and they have ways to detect that before I usually gets too bad.
    $endgroup$
    – Ron Beyer
    2 hours ago















1












$begingroup$


Virtually all first-class airline seats, and many to most business-class seats, recline all the way down, either as lie-flat seats (where the seat reclines to a 180º seatback-seatpan angle, but the fully-reclined seat is still tilted somewhat forwards relative to the cabin floor) or flat-bed seats (where the seat reclines to a truly flat surface that can also, as the name indicates, serve as a bed).



These seats are, of course, equipped with seatbelts, but I’m having great trouble seeing how even a tightly-fastened seatbelt would provide any protection to a flat-lying occupant, as any significant longitudinal force would cause the occupant of the seat to slide under the belt and out of the seat.12



Although these seats, like all airline passenger seats, are required to be locked in the fully-upright position except in cruise flight, this still leaves the occupants (especially those in flat-bed seats) vulnerable during the (sometimes quite long) portion of the flight when they are allowed to recline their seats to flatness; a moderate head-on (or tail-on, for that matter) gust would be enough to separate these occupants from their fully-reclined seats, as would any other event capable of suddenly increasing or decreasing an aircraft’s inertial speed too quickly for the “fasten seat belts” sign to provide any warning (not, as noted above, that fastening their seatbelts would actually provide any significant degree of protection to the occupants in question, but it could conceivably induce them to derecline their seats in preparation), such as a flight-control malfunction or evasive action to avoid a MAC (both of which produce large speed excursions secondary to rapid changes in attitude and altitude).



For that matter, even vertical accelerations with no longitudinal component would still be expected to injure flat-lying passengers more severely than those in an ordinary sitting position, for reasons illustrated below:



OUCH



Am I missing something?




1: This is known as submarining, and is a major problem with car seatbelts (even with seats that don’t recline at all), which are much harder to fasten tightly around the pelvis than aircraft seatbelts.



2: If the belt were fastened tightly enough to pin the occupant to the seat even under considerable longitudinal force, this would



  • be highly uncomfortable for the occupant, and

  • upon the application of significant longitudinal forces, drag across the occupant’s abdomen until catching on their ribcage, causing severe internal abdominal injuries plus likely breaking the bottom few ribs.









share|improve this question











$endgroup$











  • $begingroup$
    Can you format the first part of this so that it isn't a large wall of text?
    $endgroup$
    – Ron Beyer
    2 hours ago










  • $begingroup$
    I like your drawing.
    $endgroup$
    – vasin1987
    2 hours ago










  • $begingroup$
    Usually when the seatbelt sign goes on, especially if they ask the flight attendants to sit down, they'll ask people to bring the seat backs up. I've never heard of an instance of a "sudden" head wind or tail wind powerful enough to unseat passengers. Turbulence is a bigger issue and they have ways to detect that before I usually gets too bad.
    $endgroup$
    – Ron Beyer
    2 hours ago













1












1








1





$begingroup$


Virtually all first-class airline seats, and many to most business-class seats, recline all the way down, either as lie-flat seats (where the seat reclines to a 180º seatback-seatpan angle, but the fully-reclined seat is still tilted somewhat forwards relative to the cabin floor) or flat-bed seats (where the seat reclines to a truly flat surface that can also, as the name indicates, serve as a bed).



These seats are, of course, equipped with seatbelts, but I’m having great trouble seeing how even a tightly-fastened seatbelt would provide any protection to a flat-lying occupant, as any significant longitudinal force would cause the occupant of the seat to slide under the belt and out of the seat.12



Although these seats, like all airline passenger seats, are required to be locked in the fully-upright position except in cruise flight, this still leaves the occupants (especially those in flat-bed seats) vulnerable during the (sometimes quite long) portion of the flight when they are allowed to recline their seats to flatness; a moderate head-on (or tail-on, for that matter) gust would be enough to separate these occupants from their fully-reclined seats, as would any other event capable of suddenly increasing or decreasing an aircraft’s inertial speed too quickly for the “fasten seat belts” sign to provide any warning (not, as noted above, that fastening their seatbelts would actually provide any significant degree of protection to the occupants in question, but it could conceivably induce them to derecline their seats in preparation), such as a flight-control malfunction or evasive action to avoid a MAC (both of which produce large speed excursions secondary to rapid changes in attitude and altitude).



For that matter, even vertical accelerations with no longitudinal component would still be expected to injure flat-lying passengers more severely than those in an ordinary sitting position, for reasons illustrated below:



OUCH



Am I missing something?




1: This is known as submarining, and is a major problem with car seatbelts (even with seats that don’t recline at all), which are much harder to fasten tightly around the pelvis than aircraft seatbelts.



2: If the belt were fastened tightly enough to pin the occupant to the seat even under considerable longitudinal force, this would



  • be highly uncomfortable for the occupant, and

  • upon the application of significant longitudinal forces, drag across the occupant’s abdomen until catching on their ribcage, causing severe internal abdominal injuries plus likely breaking the bottom few ribs.









share|improve this question











$endgroup$




Virtually all first-class airline seats, and many to most business-class seats, recline all the way down, either as lie-flat seats (where the seat reclines to a 180º seatback-seatpan angle, but the fully-reclined seat is still tilted somewhat forwards relative to the cabin floor) or flat-bed seats (where the seat reclines to a truly flat surface that can also, as the name indicates, serve as a bed).



These seats are, of course, equipped with seatbelts, but I’m having great trouble seeing how even a tightly-fastened seatbelt would provide any protection to a flat-lying occupant, as any significant longitudinal force would cause the occupant of the seat to slide under the belt and out of the seat.12



Although these seats, like all airline passenger seats, are required to be locked in the fully-upright position except in cruise flight, this still leaves the occupants (especially those in flat-bed seats) vulnerable during the (sometimes quite long) portion of the flight when they are allowed to recline their seats to flatness; a moderate head-on (or tail-on, for that matter) gust would be enough to separate these occupants from their fully-reclined seats, as would any other event capable of suddenly increasing or decreasing an aircraft’s inertial speed too quickly for the “fasten seat belts” sign to provide any warning (not, as noted above, that fastening their seatbelts would actually provide any significant degree of protection to the occupants in question, but it could conceivably induce them to derecline their seats in preparation), such as a flight-control malfunction or evasive action to avoid a MAC (both of which produce large speed excursions secondary to rapid changes in attitude and altitude).



For that matter, even vertical accelerations with no longitudinal component would still be expected to injure flat-lying passengers more severely than those in an ordinary sitting position, for reasons illustrated below:



OUCH



Am I missing something?




1: This is known as submarining, and is a major problem with car seatbelts (even with seats that don’t recline at all), which are much harder to fasten tightly around the pelvis than aircraft seatbelts.



2: If the belt were fastened tightly enough to pin the occupant to the seat even under considerable longitudinal force, this would



  • be highly uncomfortable for the occupant, and

  • upon the application of significant longitudinal forces, drag across the occupant’s abdomen until catching on their ribcage, causing severe internal abdominal injuries plus likely breaking the bottom few ribs.






safety seats seatbelts






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 2 hours ago







Sean

















asked 2 hours ago









SeanSean

6,49543082




6,49543082











  • $begingroup$
    Can you format the first part of this so that it isn't a large wall of text?
    $endgroup$
    – Ron Beyer
    2 hours ago










  • $begingroup$
    I like your drawing.
    $endgroup$
    – vasin1987
    2 hours ago










  • $begingroup$
    Usually when the seatbelt sign goes on, especially if they ask the flight attendants to sit down, they'll ask people to bring the seat backs up. I've never heard of an instance of a "sudden" head wind or tail wind powerful enough to unseat passengers. Turbulence is a bigger issue and they have ways to detect that before I usually gets too bad.
    $endgroup$
    – Ron Beyer
    2 hours ago
















  • $begingroup$
    Can you format the first part of this so that it isn't a large wall of text?
    $endgroup$
    – Ron Beyer
    2 hours ago










  • $begingroup$
    I like your drawing.
    $endgroup$
    – vasin1987
    2 hours ago










  • $begingroup$
    Usually when the seatbelt sign goes on, especially if they ask the flight attendants to sit down, they'll ask people to bring the seat backs up. I've never heard of an instance of a "sudden" head wind or tail wind powerful enough to unseat passengers. Turbulence is a bigger issue and they have ways to detect that before I usually gets too bad.
    $endgroup$
    – Ron Beyer
    2 hours ago















$begingroup$
Can you format the first part of this so that it isn't a large wall of text?
$endgroup$
– Ron Beyer
2 hours ago




$begingroup$
Can you format the first part of this so that it isn't a large wall of text?
$endgroup$
– Ron Beyer
2 hours ago












$begingroup$
I like your drawing.
$endgroup$
– vasin1987
2 hours ago




$begingroup$
I like your drawing.
$endgroup$
– vasin1987
2 hours ago












$begingroup$
Usually when the seatbelt sign goes on, especially if they ask the flight attendants to sit down, they'll ask people to bring the seat backs up. I've never heard of an instance of a "sudden" head wind or tail wind powerful enough to unseat passengers. Turbulence is a bigger issue and they have ways to detect that before I usually gets too bad.
$endgroup$
– Ron Beyer
2 hours ago




$begingroup$
Usually when the seatbelt sign goes on, especially if they ask the flight attendants to sit down, they'll ask people to bring the seat backs up. I've never heard of an instance of a "sudden" head wind or tail wind powerful enough to unseat passengers. Turbulence is a bigger issue and they have ways to detect that before I usually gets too bad.
$endgroup$
– Ron Beyer
2 hours ago










2 Answers
2






active

oldest

votes


















3












$begingroup$

I'm not sure that comparing car seatbelts to airplane seatbelts is that useful here. The acceleration involved in a car crash at highway speeds are much greater than even the acceleration, mostly vertical, involved in even severe turbulence.



For example, after a 2015 severe turbulence encounter, investigators determined: "In the first event, the peak vertical acceleration forces recorded were + 1.7 and + 0.14 g. In the second event, peak vertical acceleration forces recorded were + 2.21 g and −1.32 g," not that much greater than the kind of forces you might pull in a car if you drive really aggressively. That's enough to throw unrestrained passengers and objects about (just as if you slam on the brakes in a car), resulting in injury, but it's a much smaller acceleration than what you'd see in a 30mph car crash. Nobody would consider being slammed against their seat belt like that, whether they're seated upright or reclined, to be enjoyable, but it beats slamming your head into the ceiling.



Forces much larger than that exceed the design load limits required for the aircraft, and once you're beyond that and the required safety factor, your biggest worry is the structural integrity of the aircraft, and you're less concerned about whether people's limbs flailed about.



In the case of an actual crash (such as the 16g standard new airplane seats are tested to), lying flat could pose a much larger risk of injury, but that's beyond the design specifications of the seat, which are tested with test dummies in a normal upright position. There aren't a lot of survivable accidents that occur without warning during the cruise phase of flight (page 22).



Car seats can also be reclined, and the diagrams the NHSTA produced of the results of crashes in those cases (see, for instance, page 41) are remarkably similar to yours. This is why "bring your seat to the upright position for landing" is a standard requirement.






share|improve this answer











$endgroup$












  • $begingroup$
    Actually there are many accidents that occur without warning during the cruise phase of flight, because any occurrence where somebody is injured qualifies as accident and turbulence-related injuries are quite common. But there is not much on the aircraft that the turbulence could grab to shake it in longitudinal direction, so only vertical accelerations are a concern. The linked document only counts hull-losses, which is much smaller category. In cruise a non-fatal hull-loss can only happen as emergency landing and there is obviously lot of time to put the seats upright in such case.
    $endgroup$
    – Jan Hudec
    12 mins ago


















1












$begingroup$

Yeah, even in the strongest wind gust longitudinal acceleration or deceleration is not a problem; we are talking only fraction of a G. During cruise flight sudden turbulence causes most damage and there the vertical component is critical. Even then the experienced vertical accelerations are negligible when compared to car accidents. They are enough to toss people and equipment around if not properly secured but again, the acceleration is usually less than a G.



Airframes are certified to -1/+2,5G vertical acceleration with additional margin of 50% so structural failure is likely to occur way before car wrecking forces are encountered.






share|improve this answer









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    2 Answers
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    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    3












    $begingroup$

    I'm not sure that comparing car seatbelts to airplane seatbelts is that useful here. The acceleration involved in a car crash at highway speeds are much greater than even the acceleration, mostly vertical, involved in even severe turbulence.



    For example, after a 2015 severe turbulence encounter, investigators determined: "In the first event, the peak vertical acceleration forces recorded were + 1.7 and + 0.14 g. In the second event, peak vertical acceleration forces recorded were + 2.21 g and −1.32 g," not that much greater than the kind of forces you might pull in a car if you drive really aggressively. That's enough to throw unrestrained passengers and objects about (just as if you slam on the brakes in a car), resulting in injury, but it's a much smaller acceleration than what you'd see in a 30mph car crash. Nobody would consider being slammed against their seat belt like that, whether they're seated upright or reclined, to be enjoyable, but it beats slamming your head into the ceiling.



    Forces much larger than that exceed the design load limits required for the aircraft, and once you're beyond that and the required safety factor, your biggest worry is the structural integrity of the aircraft, and you're less concerned about whether people's limbs flailed about.



    In the case of an actual crash (such as the 16g standard new airplane seats are tested to), lying flat could pose a much larger risk of injury, but that's beyond the design specifications of the seat, which are tested with test dummies in a normal upright position. There aren't a lot of survivable accidents that occur without warning during the cruise phase of flight (page 22).



    Car seats can also be reclined, and the diagrams the NHSTA produced of the results of crashes in those cases (see, for instance, page 41) are remarkably similar to yours. This is why "bring your seat to the upright position for landing" is a standard requirement.






    share|improve this answer











    $endgroup$












    • $begingroup$
      Actually there are many accidents that occur without warning during the cruise phase of flight, because any occurrence where somebody is injured qualifies as accident and turbulence-related injuries are quite common. But there is not much on the aircraft that the turbulence could grab to shake it in longitudinal direction, so only vertical accelerations are a concern. The linked document only counts hull-losses, which is much smaller category. In cruise a non-fatal hull-loss can only happen as emergency landing and there is obviously lot of time to put the seats upright in such case.
      $endgroup$
      – Jan Hudec
      12 mins ago















    3












    $begingroup$

    I'm not sure that comparing car seatbelts to airplane seatbelts is that useful here. The acceleration involved in a car crash at highway speeds are much greater than even the acceleration, mostly vertical, involved in even severe turbulence.



    For example, after a 2015 severe turbulence encounter, investigators determined: "In the first event, the peak vertical acceleration forces recorded were + 1.7 and + 0.14 g. In the second event, peak vertical acceleration forces recorded were + 2.21 g and −1.32 g," not that much greater than the kind of forces you might pull in a car if you drive really aggressively. That's enough to throw unrestrained passengers and objects about (just as if you slam on the brakes in a car), resulting in injury, but it's a much smaller acceleration than what you'd see in a 30mph car crash. Nobody would consider being slammed against their seat belt like that, whether they're seated upright or reclined, to be enjoyable, but it beats slamming your head into the ceiling.



    Forces much larger than that exceed the design load limits required for the aircraft, and once you're beyond that and the required safety factor, your biggest worry is the structural integrity of the aircraft, and you're less concerned about whether people's limbs flailed about.



    In the case of an actual crash (such as the 16g standard new airplane seats are tested to), lying flat could pose a much larger risk of injury, but that's beyond the design specifications of the seat, which are tested with test dummies in a normal upright position. There aren't a lot of survivable accidents that occur without warning during the cruise phase of flight (page 22).



    Car seats can also be reclined, and the diagrams the NHSTA produced of the results of crashes in those cases (see, for instance, page 41) are remarkably similar to yours. This is why "bring your seat to the upright position for landing" is a standard requirement.






    share|improve this answer











    $endgroup$












    • $begingroup$
      Actually there are many accidents that occur without warning during the cruise phase of flight, because any occurrence where somebody is injured qualifies as accident and turbulence-related injuries are quite common. But there is not much on the aircraft that the turbulence could grab to shake it in longitudinal direction, so only vertical accelerations are a concern. The linked document only counts hull-losses, which is much smaller category. In cruise a non-fatal hull-loss can only happen as emergency landing and there is obviously lot of time to put the seats upright in such case.
      $endgroup$
      – Jan Hudec
      12 mins ago













    3












    3








    3





    $begingroup$

    I'm not sure that comparing car seatbelts to airplane seatbelts is that useful here. The acceleration involved in a car crash at highway speeds are much greater than even the acceleration, mostly vertical, involved in even severe turbulence.



    For example, after a 2015 severe turbulence encounter, investigators determined: "In the first event, the peak vertical acceleration forces recorded were + 1.7 and + 0.14 g. In the second event, peak vertical acceleration forces recorded were + 2.21 g and −1.32 g," not that much greater than the kind of forces you might pull in a car if you drive really aggressively. That's enough to throw unrestrained passengers and objects about (just as if you slam on the brakes in a car), resulting in injury, but it's a much smaller acceleration than what you'd see in a 30mph car crash. Nobody would consider being slammed against their seat belt like that, whether they're seated upright or reclined, to be enjoyable, but it beats slamming your head into the ceiling.



    Forces much larger than that exceed the design load limits required for the aircraft, and once you're beyond that and the required safety factor, your biggest worry is the structural integrity of the aircraft, and you're less concerned about whether people's limbs flailed about.



    In the case of an actual crash (such as the 16g standard new airplane seats are tested to), lying flat could pose a much larger risk of injury, but that's beyond the design specifications of the seat, which are tested with test dummies in a normal upright position. There aren't a lot of survivable accidents that occur without warning during the cruise phase of flight (page 22).



    Car seats can also be reclined, and the diagrams the NHSTA produced of the results of crashes in those cases (see, for instance, page 41) are remarkably similar to yours. This is why "bring your seat to the upright position for landing" is a standard requirement.






    share|improve this answer











    $endgroup$



    I'm not sure that comparing car seatbelts to airplane seatbelts is that useful here. The acceleration involved in a car crash at highway speeds are much greater than even the acceleration, mostly vertical, involved in even severe turbulence.



    For example, after a 2015 severe turbulence encounter, investigators determined: "In the first event, the peak vertical acceleration forces recorded were + 1.7 and + 0.14 g. In the second event, peak vertical acceleration forces recorded were + 2.21 g and −1.32 g," not that much greater than the kind of forces you might pull in a car if you drive really aggressively. That's enough to throw unrestrained passengers and objects about (just as if you slam on the brakes in a car), resulting in injury, but it's a much smaller acceleration than what you'd see in a 30mph car crash. Nobody would consider being slammed against their seat belt like that, whether they're seated upright or reclined, to be enjoyable, but it beats slamming your head into the ceiling.



    Forces much larger than that exceed the design load limits required for the aircraft, and once you're beyond that and the required safety factor, your biggest worry is the structural integrity of the aircraft, and you're less concerned about whether people's limbs flailed about.



    In the case of an actual crash (such as the 16g standard new airplane seats are tested to), lying flat could pose a much larger risk of injury, but that's beyond the design specifications of the seat, which are tested with test dummies in a normal upright position. There aren't a lot of survivable accidents that occur without warning during the cruise phase of flight (page 22).



    Car seats can also be reclined, and the diagrams the NHSTA produced of the results of crashes in those cases (see, for instance, page 41) are remarkably similar to yours. This is why "bring your seat to the upright position for landing" is a standard requirement.







    share|improve this answer














    share|improve this answer



    share|improve this answer








    edited 1 hour ago

























    answered 1 hour ago









    Zach LiptonZach Lipton

    6,91912943




    6,91912943











    • $begingroup$
      Actually there are many accidents that occur without warning during the cruise phase of flight, because any occurrence where somebody is injured qualifies as accident and turbulence-related injuries are quite common. But there is not much on the aircraft that the turbulence could grab to shake it in longitudinal direction, so only vertical accelerations are a concern. The linked document only counts hull-losses, which is much smaller category. In cruise a non-fatal hull-loss can only happen as emergency landing and there is obviously lot of time to put the seats upright in such case.
      $endgroup$
      – Jan Hudec
      12 mins ago
















    • $begingroup$
      Actually there are many accidents that occur without warning during the cruise phase of flight, because any occurrence where somebody is injured qualifies as accident and turbulence-related injuries are quite common. But there is not much on the aircraft that the turbulence could grab to shake it in longitudinal direction, so only vertical accelerations are a concern. The linked document only counts hull-losses, which is much smaller category. In cruise a non-fatal hull-loss can only happen as emergency landing and there is obviously lot of time to put the seats upright in such case.
      $endgroup$
      – Jan Hudec
      12 mins ago















    $begingroup$
    Actually there are many accidents that occur without warning during the cruise phase of flight, because any occurrence where somebody is injured qualifies as accident and turbulence-related injuries are quite common. But there is not much on the aircraft that the turbulence could grab to shake it in longitudinal direction, so only vertical accelerations are a concern. The linked document only counts hull-losses, which is much smaller category. In cruise a non-fatal hull-loss can only happen as emergency landing and there is obviously lot of time to put the seats upright in such case.
    $endgroup$
    – Jan Hudec
    12 mins ago




    $begingroup$
    Actually there are many accidents that occur without warning during the cruise phase of flight, because any occurrence where somebody is injured qualifies as accident and turbulence-related injuries are quite common. But there is not much on the aircraft that the turbulence could grab to shake it in longitudinal direction, so only vertical accelerations are a concern. The linked document only counts hull-losses, which is much smaller category. In cruise a non-fatal hull-loss can only happen as emergency landing and there is obviously lot of time to put the seats upright in such case.
    $endgroup$
    – Jan Hudec
    12 mins ago











    1












    $begingroup$

    Yeah, even in the strongest wind gust longitudinal acceleration or deceleration is not a problem; we are talking only fraction of a G. During cruise flight sudden turbulence causes most damage and there the vertical component is critical. Even then the experienced vertical accelerations are negligible when compared to car accidents. They are enough to toss people and equipment around if not properly secured but again, the acceleration is usually less than a G.



    Airframes are certified to -1/+2,5G vertical acceleration with additional margin of 50% so structural failure is likely to occur way before car wrecking forces are encountered.






    share|improve this answer









    $endgroup$

















      1












      $begingroup$

      Yeah, even in the strongest wind gust longitudinal acceleration or deceleration is not a problem; we are talking only fraction of a G. During cruise flight sudden turbulence causes most damage and there the vertical component is critical. Even then the experienced vertical accelerations are negligible when compared to car accidents. They are enough to toss people and equipment around if not properly secured but again, the acceleration is usually less than a G.



      Airframes are certified to -1/+2,5G vertical acceleration with additional margin of 50% so structural failure is likely to occur way before car wrecking forces are encountered.






      share|improve this answer









      $endgroup$















        1












        1








        1





        $begingroup$

        Yeah, even in the strongest wind gust longitudinal acceleration or deceleration is not a problem; we are talking only fraction of a G. During cruise flight sudden turbulence causes most damage and there the vertical component is critical. Even then the experienced vertical accelerations are negligible when compared to car accidents. They are enough to toss people and equipment around if not properly secured but again, the acceleration is usually less than a G.



        Airframes are certified to -1/+2,5G vertical acceleration with additional margin of 50% so structural failure is likely to occur way before car wrecking forces are encountered.






        share|improve this answer









        $endgroup$



        Yeah, even in the strongest wind gust longitudinal acceleration or deceleration is not a problem; we are talking only fraction of a G. During cruise flight sudden turbulence causes most damage and there the vertical component is critical. Even then the experienced vertical accelerations are negligible when compared to car accidents. They are enough to toss people and equipment around if not properly secured but again, the acceleration is usually less than a G.



        Airframes are certified to -1/+2,5G vertical acceleration with additional margin of 50% so structural failure is likely to occur way before car wrecking forces are encountered.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 1 hour ago









        busdriverbusdriver

        4936




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