Originally Posted by KCJeep
After nearly 11 years in crash investigation and reconstruction of fatality and serious injury crashes, I mostly agree with the teacher. Air bags help, but if seat belt compliance was 100% we mostly wouldn't even need them. While they can be helpful, especially in an extreme head on collision, they are useless in a lot of other scenarios (such as a roll over).
They add a tremendous amount of expense to the vehicle, have needlessly caused injuries and fatalities (can you say Takata) and are a common source of incidental recalls as well. There is now a new one on my KIA over a sensor. My Lincoln just had the passenger side replaced over the Takata debacle. Of course we had been driving around with my wife over there before we knew about it.
As mentioned, I have seen a lot of fatalities that were completely avoidable due lack of seat belt use, many at low speeds (such as a roll over down into a ditch in inclement weather). I don't remember ever taking a fatality where we said "If only the air bag had worked better, he'd be alive now".
What I don't like is how they're reported. There was a local story here not too long ago where someone out on bail was running from the police and did a head on collision with another driver who was just coming back from the hospital after his wife gave birth. They both died but it did mention one passenger who was ejected and later died. No mention of seat belts. I'm kinda guessing that no one was wearing a seat belt. But who knows, the speed limit on that road is about 40 and even with a speeding car a head on collision might be survivable with seat belt and air bags, the guy was driving an SUV too so it should have been a bit more survivable. But most of the time whenever there's an accident, that info is never included.