View Full Version : Brace position with an airbag?


Contacttower
11th Jan 2010, 20:57
Some light aircraft are now fitted with airbags in the lap belts; I can't find any guidance anywhere as to whether this changes the recommended brace position...any thoughts?...Would for example the adoption of the conventional brace position interfere with the airbag deployment?



AdamFrisch
11th Jan 2010, 22:17
Morbidly, I've heard the only reason the brace position is recommended is so that they easier can identify the bodies in a post crash scenario (since upright heads get hit by debris and can, well, get misplaced..):ooh::oh::uhoh:

Don't know if it's true.

soay
12th Jan 2010, 12:23
This AmSafe video should help you make up your mind about the brace position:

lZfPJG3LXxk

It doesn't look to me as though it would be of any benefit.

tdbristol
12th Jan 2010, 12:24
I fly an aircraft with airbags in the front and have asked this question of the aircraft manufacturer and their reply was "don't know".
However, if you look on the Amsafe website it shows the dummy sitting upright, arms at the sides, with the airbag deploying in front between the dash and the person.
I think if you were leaning forward the airbag might hit you in the face.
It seems logical to me for Amsafe to assume that the person would be upright, as would be the case with the pilot controlling the airplane (as implied by the Amsafe videos).
And the seatbelts are inertia reel, which clearly stop/reduce forward motion as well.
Overall it seems to me in the aircraft that I fly that injury is most likely to come from hitting the dash parts (or vice versa), as it is rapid forward deceleration that is most likely to occur in the event of a crash.

So I tell my pax to adopt the following brace position:
- bolt upright, with their back and head hard against the seat back (stiff as possible)
- arms at their sides, braced as far as possible to help keep upright.
It seems to me that the possible drawback with this is that the head is higher and therefore nearer the top edge of the cockpit, which could be an issue if you flip upside down, depending how strong the cockpit ceiling is.
(Although the Amsafe website does show a few video reconstructions of airplanes cartwheeling and landing upside down, with no head injuries.)

Anyway, I guess you have to make your own judgement on this.

BackPacker
12th Jan 2010, 12:45
The brace position is only relevant if you don't have a shoulder belt, just a lap belt. The brace position is supposed to prevent/limit injury to your upper torso and head when they're thrown forward against something due to the sudden deceleration in a crash. What you essentially do is move your torso and head as far forward as they will go, either until your body can't go any further forward (the typical "business class" brace position where you're completely bent over, with your arms wrapped around your upper legs) or because you lean against the object in front of you (the typical "economy class" brace position where you lean against the seatback in front of you).

In an aircraft with shoulder belts, or four- or five-point harnasses your upper torso is restrained (assuming you actually wear the shoulder belt properly) and your head is too far from any solid object to hit.

- bolt upright, with their back and head hard against the seat back (stiff as possible)
- arms at their sides, braced as far as possible to help keep upright.

I'm not a safety expert but it seems to me that this advice may (note: "may") cause further injuries. In a significant crash, you will never be able to withstand the deceleration by muscle power alone. So:
- if you have pre-tensioned your muscles to keep your head hard against the seat/head rest, your head will be flung forward anyway. But then the tension in your muscles will then cause your head to be flung BACK against the headrest. If that headrest is not properly adjusted, or absent completely, this may actually cause a whiplash. (This is the main reason for having head "rests" in cars.)
- If you brace and lock your arms against the dash the forces are so great that you may actually break your arms.

My idea would be that you need to let the safety devices, particularly the seat belts, do their job. That means that they need to be as tight as possible. (Until it hurts and then some...) That's something which requires conscious effort if you do not have inertia-reel lap or shoulder belts, but even if you have inertia-reel belts you need to make sure that bulky clothing does not loosen them up. Assuming you're properly strapped in, a limp body will probably suffer less injury than a tensed up body.

And if you do have airbags, make sure there's nothing in the way that hampers their deployment.

Contacttower
12th Jan 2010, 15:50
Thanks guys, that was just the sort of advice I was looking for. It would seem to make sense as well so I'm surprised that tdbristol got a 'don't know' from the aircraft maker.

Assuming you're properly strapped in, a limp body will probably suffer less injury than a tensed up body.

I'm not a safety expert either but in general I've always understood that to be broadly correct.

xj8driver
12th Jan 2010, 16:07
Assuming you're properly strapped in, a limp body will probably suffer less injury than a tensed up body.

I agree; there have been many instances where sleeping car passengers have been unhurt in a road crash where others in the same car have not been so lucky

BackPacker
12th Jan 2010, 18:40
Irony, isn't it? You're about to crash and the best advice is "relax".:ok: