U.S. Airline May Fit Airbags In Aircraft Seats
How many seats have come off the mounts versus not?
OTOH most of others have come off their mounts when they were involved in a non-survivable crash. Do those facts help?
I'm not exactly sure what senses the airbag to inflate. Would it be the brat kid sitting behind me that keeps kicking the back of my seat?
Moderator
Not a new idea at all. FAA's CAMI has been at the forefront of researching the use of airbags in aircraft for a long time.
Not really a great help when the seats come off the mounts!
Static design standard seats (the old 9g and earlier 6g seats) generally had comparatively rigid track mounting provisions and presented retention problems in a dynamic crash situation. Many of the 9g seats, for convenience, were tested to 12g for the attachment test without any additional reinforcing and it was a case of crash floor buckling leading to track twisting and lip departure which was the problem.
The case of crash loads being far above the design requirements in a severe impact is a case which is not considered as suggested by lomapaseo.
Interestingly, CAMI did some full scale sled tests a long time ago with static standard seats and, as I recall, the results were not too bad.
However, the dynamic seats have requirements which are better related to the real world of floor deformation with the result that we would expect dynamic seats to perform far better in crashes.
In addition, the requirements vary according to the class of aircraft for which the seats are intended. This reflects the observation that the "real" load experienced by the seat in a crash is very dependent on the vehicle in which it is located .. a widebody airliner imposes the lowest expected seat crash loads while, in general, a helicopter imposes the highest .. the helicopter dynamic seat generally requires a seat frame stroking mechanism to provide enough distance over which the impact is absorbed to achieve the maximum permitted test dummy loads on the certification tests.
Depends what sets off the airbag
I'm a bit out of touch with seat design these days but, presuming that things haven't moved too far in the bang department, we probably are still looking at sodium azide as the propellant (solid explosive with an electrical initiation from a g-switch and moderately nasty sort of stuff).
Which aircraft do you know that pull 40-odd G during a landing?
Whether we are talking cars or planes, the initiation is matched to the impulse signature .. the bag goes off a long way before the accelerations get to 40g. Keep in mind the idea is to time things so the bag is fully inflated well before the head impacts it .. and then is deflating so that the head impact into the bag surface is lessened. "Bag slap", which is the term usually given to a mistimed firing in which the bag is still inflating as the head impacts it .. is not a good thing at all.
This need for initiation to be matched closely to the impact pulse signature (which is very much related to the structure and its deformation characteristics) is why one ought not modify a car's structure by, eg, putting a non-OEM authorised bullbar on a vehicle with airbags .. good way to get an unsatisfactory result when the bag is most needed. Even sticking on after-market bits and pieces to the approved bullbar might have minor effects on the pulse characteristics.
The marketing desire to represent bags as nice, soft, fluffy headrests is not helpful .. the thing is an explosive device and goes off with an almighty bang. If you get a chance to see the very early CAMI films of their sled test unit fitted with bags it is worth the interest to see how even the experts can get some aspects very wrong if the research is not rigorous (in this case the folk got a big surprise to find themselves surrounded with nasty combustion byproducts which should have been captured by filters, such as are incorporated into an auto bag installation... lots of sodium hydroxide and like nasties, as I recall .. resulting in a rapid exit, stage left.
I believe the airbag will be for bulkhead seats
CAMI's earlier research (I haven't kept up with recent papers so things may have changed a bit) suggested that the best way to approach the bulkhead problem was by the use of a fixed installation of Hexcel. This proprietary honeycomb structure of very lightweight aluminium provided an appropriate force-deflection characteristic for head impact .. many may not be aware that simple foam (and the like) cushions are quite inappropriate for impact cushioning as the force-deflection characteristics are very rate dependent .. what this means is that a fast moving head might just as well be hitting a brick wall as a medium to high density foam cushion .. Hexcel, on the other hand, deformed nicely with little, if any, impact rate dependence.
Come back, rear-facing seats
Introduces a lot of other problems and not necessarily the better option.
HIC
It is worth noting that a high, but "acceptable" value for HIC is not something that you or I would enjoy experiencing. While we will see an improvement in survivability, we will also see, as with auto crashes, an increase in severe injuries and ongoing debility in cases which would have been fatal with earlier technology ..
.. and, if you really want to improve your survival chances, opt for a full harness (the TARC harness, such as is fitted to most F/A seats is the way to go) with bags to provide a supplementary protection. .. just having upper body restraint gives a notional reduction in head impact velocity of around 50 percent (note that it doesn't necessarily prevent your impacting surrouding structure due to the normal stretch characteristics of belting .. but that reduction in impact velocity has a mighty effect on the HIC outcomes.
... hence the preference for lapsash installations in motor vehicles rather than lapbelt only.
Not really a great help when the seats come off the mounts!
Static design standard seats (the old 9g and earlier 6g seats) generally had comparatively rigid track mounting provisions and presented retention problems in a dynamic crash situation. Many of the 9g seats, for convenience, were tested to 12g for the attachment test without any additional reinforcing and it was a case of crash floor buckling leading to track twisting and lip departure which was the problem.
The case of crash loads being far above the design requirements in a severe impact is a case which is not considered as suggested by lomapaseo.
Interestingly, CAMI did some full scale sled tests a long time ago with static standard seats and, as I recall, the results were not too bad.
However, the dynamic seats have requirements which are better related to the real world of floor deformation with the result that we would expect dynamic seats to perform far better in crashes.
In addition, the requirements vary according to the class of aircraft for which the seats are intended. This reflects the observation that the "real" load experienced by the seat in a crash is very dependent on the vehicle in which it is located .. a widebody airliner imposes the lowest expected seat crash loads while, in general, a helicopter imposes the highest .. the helicopter dynamic seat generally requires a seat frame stroking mechanism to provide enough distance over which the impact is absorbed to achieve the maximum permitted test dummy loads on the certification tests.
Depends what sets off the airbag
I'm a bit out of touch with seat design these days but, presuming that things haven't moved too far in the bang department, we probably are still looking at sodium azide as the propellant (solid explosive with an electrical initiation from a g-switch and moderately nasty sort of stuff).
Which aircraft do you know that pull 40-odd G during a landing?
Whether we are talking cars or planes, the initiation is matched to the impulse signature .. the bag goes off a long way before the accelerations get to 40g. Keep in mind the idea is to time things so the bag is fully inflated well before the head impacts it .. and then is deflating so that the head impact into the bag surface is lessened. "Bag slap", which is the term usually given to a mistimed firing in which the bag is still inflating as the head impacts it .. is not a good thing at all.
This need for initiation to be matched closely to the impact pulse signature (which is very much related to the structure and its deformation characteristics) is why one ought not modify a car's structure by, eg, putting a non-OEM authorised bullbar on a vehicle with airbags .. good way to get an unsatisfactory result when the bag is most needed. Even sticking on after-market bits and pieces to the approved bullbar might have minor effects on the pulse characteristics.
The marketing desire to represent bags as nice, soft, fluffy headrests is not helpful .. the thing is an explosive device and goes off with an almighty bang. If you get a chance to see the very early CAMI films of their sled test unit fitted with bags it is worth the interest to see how even the experts can get some aspects very wrong if the research is not rigorous (in this case the folk got a big surprise to find themselves surrounded with nasty combustion byproducts which should have been captured by filters, such as are incorporated into an auto bag installation... lots of sodium hydroxide and like nasties, as I recall .. resulting in a rapid exit, stage left.
I believe the airbag will be for bulkhead seats
CAMI's earlier research (I haven't kept up with recent papers so things may have changed a bit) suggested that the best way to approach the bulkhead problem was by the use of a fixed installation of Hexcel. This proprietary honeycomb structure of very lightweight aluminium provided an appropriate force-deflection characteristic for head impact .. many may not be aware that simple foam (and the like) cushions are quite inappropriate for impact cushioning as the force-deflection characteristics are very rate dependent .. what this means is that a fast moving head might just as well be hitting a brick wall as a medium to high density foam cushion .. Hexcel, on the other hand, deformed nicely with little, if any, impact rate dependence.
Come back, rear-facing seats
Introduces a lot of other problems and not necessarily the better option.
HIC
It is worth noting that a high, but "acceptable" value for HIC is not something that you or I would enjoy experiencing. While we will see an improvement in survivability, we will also see, as with auto crashes, an increase in severe injuries and ongoing debility in cases which would have been fatal with earlier technology ..
.. and, if you really want to improve your survival chances, opt for a full harness (the TARC harness, such as is fitted to most F/A seats is the way to go) with bags to provide a supplementary protection. .. just having upper body restraint gives a notional reduction in head impact velocity of around 50 percent (note that it doesn't necessarily prevent your impacting surrouding structure due to the normal stretch characteristics of belting .. but that reduction in impact velocity has a mighty effect on the HIC outcomes.
... hence the preference for lapsash installations in motor vehicles rather than lapbelt only.
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VS have had "airbags" on the lapstraps of Upper Class suites since they were launched some years ago. The image below shows the strap which is thicker than a normal belt but quite soft and not really noticable in normal use. Don't think any have gone off in error..
http://farm3.static.flickr.com/2254/...26ebda051b.jpg
http://farm3.static.flickr.com/2254/...26ebda051b.jpg
Last edited by strake; 20th Mar 2009 at 05:35.
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Virgin Atlantic and Air New Zealand already have airbags fitted into the seatbelts of their J class seats. These are the herringbone layout J class where the pax can have the seat in any of the reclined positions for take-off or landing.
Nothing new here. Get out of those moist knickers and have a lie down kiddies!
Nothing new here. Get out of those moist knickers and have a lie down kiddies!
Paxing All Over The World
Thank you john_tullamarine, a most interesting and constructive post on all counts.
A prang that is not survivable is just that, but a bad runway excursion, or a touchdown that is not fully controlled (for whatever reason)? My guess is that you will start to see these fitted in some cases to a new a/c - firstly in J + C but it will be seen as a competitive advantage. When the world recession ends, the cost of adding these to a new machine will not be that great.
A prang that is not survivable is just that, but a bad runway excursion, or a touchdown that is not fully controlled (for whatever reason)? My guess is that you will start to see these fitted in some cases to a new a/c - firstly in J + C but it will be seen as a competitive advantage. When the world recession ends, the cost of adding these to a new machine will not be that great.
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200 odd airbags going off at once...
...produce a pretty loud bang 
So apart from being thrown across the plane strapped to your - now loose - seat you'd be left deaf for sure.
200 deaf folks after every malfunction - me as a hearing aid engineer would certainly be happy about this idea
Safe flying !
So apart from being thrown across the plane strapped to your - now loose - seat you'd be left deaf for sure.200 deaf folks after every malfunction - me as a hearing aid engineer would certainly be happy about this idea
Safe flying !
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I wouldn´t be surprised if the old idea of supplying
parachutes come up again. Probably rear facing
seats would be the only solution to improve safety
in the cabin. But passengers have always opposed
it and they in the end have the saying.
parachutes come up again. Probably rear facing
seats would be the only solution to improve safety
in the cabin. But passengers have always opposed
it and they in the end have the saying.
200 odd airbags going off at once...
...produce a pretty loud bang
...produce a pretty loud bang
Alternatively, it would save Al Quaida the trouble of getting explosives on board an aircraft, all they need to do is "hack" through the computer firewall on a 787 and trigger all the passenger airbags simultaneously
- or maybe it's a cunning anti-hijacking self-destruct mechanism........
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I wonder if my previous post is invisible to those who write "..airbags on aircraft are coming" or ..they might be dangerous.."
Virgin Atlantic have been using them since 2006.
Here's more on the subject from 2006..with diagrams and videos
Putting Air Bags in the Air - WSJ.com
Virgin Atlantic have been using them since 2006.
Here's more on the subject from 2006..with diagrams and videos
Putting Air Bags in the Air - WSJ.com
We had them on the 346 as does VS, although ours have gone back, it was/is a regulatory requirement. Fitted in bulkhead rows in EY, and now in the herringbone config (which I hate), been around a good few years now. And yes they have gone off accidently.
