For 1990-2009 cars

The driver's and right front passenger's frontal airbags are designed to inflate in moderate to severe frontal or near-frontal crashes. But they are designed to inflate only if the impact exceeds a predetermined deployment threshold. Deployment thresholds take into account a variety of desired deployment and non-deployment events and are used to predict how severe a crash is likely to be in time for the airbags to inflate and help restrain the occupants. Whether your frontal airbags will or should deploy is not based on how fast your vehicle is traveling. It depends largely on what you hit, the direction of the impact and how quickly your vehicle slows down.

The driver's and right front passenger's frontal air bags are designed to inflate in moderate to severe frontal or near frontal crashes. But they are designed to inflated only if the impact speed is above the system's designed "threshold level." If your vehicle goes straight into a wall that does not move or deform, the threshold level for the reduced deployment is about 10 to 15 mph (16 to 24 km/h). (The threshold level can vary, however, with specific vehicle design, so that it can be somewhat above or below this range.)

If your vehicle strikes something that will move or deform, such as a parked car, the threshold level will be higher. The driver's and with-front passenger's frontal air bags are not designed to inflate in rollovers, side impacts, or rear impacts, because inflation would not help the occupant.

The side impact airbags are designed to inflate in moderate to severe side crashes. A side impact airbag will inflate if the crash severity is above the system's designed "threshold level." The threshold level can vary with specific vehicle design. Side impact airbags are not designed to inflate in frontal or near-frontal impacts, rollovers or rear impacts, because inflation would not likely help the occupant. A side impact airbag will only deploy on the side of the vehicle that is struck.

It is possible that, in a crash involving the front of your vehicle, only one of the two frontal airbags in your vehicle will deploy. This is rare, but it can happen in a crash just severe enough to make a frontal airbag inflate.

In any particular crash, no one can say whether an airbag should have inflated simply because of the damage to a vehicle or because of what the repair costs were. For frontal airbags, inflation is determined by the angle of the impact and how quickly the vehicle slows down in frontal and near-frontal impacts. For side impact airbags, inflation is determined by the location and severity of the impact.