Why didn't airbag go off on '03?

There is a finite angle at which it will go off, mainly due to head rebound through side windows & other such nasties. I think it's 30 degrees or similar.

Nope my crystal ball is blank I dont even know what 03 is . If an airbag fails to deploy it is likely that the force of the impact is insufficient to trip the sensor in the case of impact with a smaller vehicle the acceleration/deceleration is likely to be greater in that vehicle and more likely to trip the MEMS accelerometer . Chest injuries in an impact are usually due to the action of the seatbelt better a bruised chest than head injury I would say. see Wikipedia--

bags are typically designed to deploy in frontal and near-frontal collisions, which are comparable to hitting a solid barrier at approximately 8 to 14 miles per hour (mph) (13 to 23 km/h). Roughly speaking, a 14 mph (23 km/h) barrier collision is equivalent to striking a parked car of similar size across the full front of each vehicle at about 28 mph (45 km/h). This is because the parked car absorbs some of the energy of the crash, and is pushed by the striking vehicle. Derek

I presume from the term "wreck" that the op is American. US airbags are very different from everyone else's - the US ones are designed to do the job of seat belts, whereas everyone else's are intended to assist the seat belt - ours inflate more slowly and are smaller sized. Land Rover's system is designed with off-road driving in mind (a lot of other systems require switching off when going off-road), and have rather more complex algorithm to cope with dropping off rocks and the like where "legal" sudden decelerations are highly likely - lord only knows what that algorithm is! Without exact details of the op's accident and the full details of US requirements it's pretty much impossible to say if the air bag should have deployed or not - US spec air bags, due to their faster inflation and larger size, are well know to actually cause minor injury, though usually preventing much worse - that's why the UK press had the scaremongering headlines about air bags "killing people" a year or two back - so I'd hazard a guess that they are more reluctant to deploy. Speaking in purely speculative mode, from what I learned while working in the automotive industry, I'd suggest the bag did indeed work correctly - the minor injuries described are pretty much the same as would have been recieved from a US spec air back "accidently" going off.

Richard

Richard

On or around Sun, 07 Jan 2007 16:32:27 GMT, "Derek" enlightened us thusly:

is it a acceleration sensor or an impact sensor? If the latter, and you have a "brush guard", will it prevent the sensor from being hit?

just my $0.02

I thought they worked on a 'crush can' principle rather than deceleration. If the force is enough to squash the deformable part of the front dumb iron then the bag goes off. But that's just from somewhere at the back of my head.

I can't see how the airbag going off would have prevented a minor chest injury which presumably came from the seat belt, both the impact and the pretensioners. These forces would still have been applied.

Land Rover do indeed make a big fuss about fitting the correct brush guards/nudge bars to airbag equipped vehicles - the design has to be correct or it will interfere with airbag operation.

Richard

It's an accelerometer, which produces a wave form that can be analysed to spot the difference between a crash and, say, going up the kerb a bit sharpish.

Richard

IIRC it's an accelerometer and a number of physical damage sensors - something along the lines of a minimum of 2 detection mechanisms must trip in order for the airbags to deploy.

I expect the 'brush guard' will be the culprit in this case - my experience in fitting airbag safe nudge bars and bull bars had shown me that they are so weakly built/attached that they are a liability and offer no protection.