I remember the same discussions as Alfa. They were initially designed as a stand alone safety mechanism. I'm guessing that has changed with all the "airbags can kill you" fear we have had since. It's a great question-is there a regulated set of parameters for airbag deployment or are the manufacturers just held to passing the crash tests?
Wow. There's so many things that could go into this... the Occupant Restraint Controller (ORC) is a self contained logic unit and it also powers the air bags. If wires going to a bag were cut before the ORC said 'fire' then no they couldn't go off. Same could happen if the wiring to one or more external sensors was cut. In fact, that's why it's rare to see an external sensor on new cars, the engineers have moved those sensors into the ORC.
Front bags typically won't go off until a given deceleration rate is reached and that has to happen within a given angle from the vehicle centerline which IIRC is 22 degrees either side for a total of 44 degrees. If something hits the car outside of those parameters then no the bag won't go off.
In reply to Curmudgeon:
Thanks for that answer. That is something to take into consideration.
And FYI for everyone, no one is suing Mercedes. There is much more involved with this accident that I can't elaborate on. The police report said that the airbags had not deployed. We were trying to figure out why that would have happened hitting so many things.
Gal brings a CTS into my shop hit in the side and is pissed off that the side bags didn't deploy. Goes so far as to have a GM rep come and inspect the car.
Today I find out (after having fixed the car) that the SRS light was on prior to the crash because the passenger seat occupancy sensor had failed. Owner neglected to share this bit of information.
There's all sorts of reasons bags may not have deployed. Owners too cheap to fix a problem when it exists is certainly one of them.
I think maybe you guys are putting too much power in the hands of the auto manufacturers engineers. I presume the government still creates the standards, and they may defy common sense ... Ford and Eaton did airbag testing in the 60's that proved pretty conclusively that the standards they were supposed to meet (Restrain an unbelted adult male) would kill short people and kids. The Government ignored the science, went ahead and ordered the overpowered killerbags, and murdered a couple of thousand people in low speed crashes. Right around 99, they reset the standards, and everybody was able to put in less powerful bags.
I stand by my original statement that there may have never been a significant enough impact the blow the bags. Besides- in a crash like that, they are useless. Blow the bags, absorb the initial impact, bags deflate, then the passengers continue to bounce around the interior of the car until it comes to a stop.
even now, an airbag could kill someone. they still deploy at 200 mph over 1/30th of a second. its basically a consideration of which force is more dangerous, the risk of the airbag, or the risk of the conditions currently happening.
an airbag computer's job is to judge the inertial forces at play on the vehicle, and if the deceleration profile that it experiences is too severe, it deploys.
therefore, if the impact didnt cause a dangerous deceleration factor in the direction an airbag is designed to deploy, then it wont.
how dangerous? worse than a 200 mph airbag to the body at 1/30th of a second. the sudden deceleration would be measured in fractions of a second, from 30mph or greater, are used to deploy them. but your speed doesnt matter truly. its how rapidly your car is decelerating.
That makes sense. If the car is bouncing over, around, and through objects, it looks bad. But the deceleration is less than hitting a more solid object and coming to a stop.
It will be near impossible to get a solid answer. As noted already, there are computers that measure an immense amount of data and then make the decision to deploy the bags. The variables are almost infinite. Plus, as also already said, you'd have to rule out system malfunction too.
I have probably seen 30-40k crashed cars, maybe more. I have seen bags go off when you would never expect it, and not go off when you'd think they should. All the variables that happen during the event, which we don't see in the aftermath, make those decisions.
Klayfish wrote: It will be near impossible to get a solid answer. As noted already, there are computers that measure an immense amount of data and then make the decision to deploy the bags. The variables are almost infinite. Plus, as also already said, you'd have to rule out system malfunction too.
There are a lot of factors but not that many. There are kids' toys with more complex code in them these days.
Airbags were developed heavily in the 70s and even introduced by GM on its larger cars in limited numbers mostly to municipalities, etc. These early designs were to act as passive restraints following Federal mandates. GM even marketed theirs for use with lap belts in cars without shoulder belts. They were originally considered as an alternative or passive restraint because not enough Americans were using seat-belts. https://www.airbagsolutions.com/history2.aspx
You'll need to log in to post.
