Roof-mounted side impact airbags are “rollover capable”and are intended to inflate in moderate to severe sidecrashes or during a rollover. Roof-mounted side impactairbags are not intended to inflate in frontal or near-frontalimpacts or rear impacts. A side impact airbag will inflate ifthe crash severity is above the system’s designed“threshold level.” The threshold level can vary withspecific vehicle design. A side impact airbag is intendedto deploy on the side of the vehicle that is struck.In any particular crash, no one can say whether an airbagshould have inflated simply because of the damage to avehicle or because of what the repair costs were. Forfrontal airbags, inflation is determined by what the vehiclehits, the angle of the impact, and how quickly the vehicleslows down in frontal and near-frontal impacts. For sideimpact airbags, inflation is determined by the location andseverity of the impact.What Makes an Airbag Inflate?In an impact of sufficient severity, the airbag sensingsystem detects that the vehicle is in a crash. In the caseof a “rollover capable” roof-mounted side impact airbag,the sensing system detects that the vehicle is about to rollover. The sensing system triggers a release of gas fromthe inflator, which inflates the airbag. The inflator, airbagand related hardware are all part of the airbag modulesinside the steering wheel, instrument panel, the side ofthe front seatbacks closest to the door and the ceiling ofthe vehicle, near the side windows.How Does an Airbag Restrain?In moderate to severe frontal or near frontal collisions,even belted occupants can contact the steering wheelor the instrument panel. In moderate to severe sidecollisions, even belted occupants can contact the insideof the vehicle. The airbag supplements the protectionprovided by safety belts. Airbags distribute the force ofthe impact more evenly over the occupant’s upperbody, stopping the occupant more gradually. But thefrontal airbags would not help you in many typesof collisions, including rollovers, rear impacts, and manyside impacts, primarily because an occupant’s motionis not toward the airbag. Side impact airbags would nothelp you in many types of collisions, including manyfrontal or near frontal collisions, and rear impacts,primarily because an occupant’s motion is not towardthose airbags. Airbags should never be regardedas anything more than a supplement to safety belts, andthen only in moderate to severe frontal or near-frontalcollisions for the driver’s and right front passenger’sfrontal airbags, and only in moderate to severeside collisions for side impact airbags.1-58
