[The ORIG. Dig. Oxy]

There are many variables involved in the air bags not going off in an accident, all pre-calculated.

If Your vehicle struck head on, but at less than a certain angle, the airbags won't go off.

If you impacted at less than 15mph.

If you were hit from the side (though, nowadays several manufacturers offer side airbags as well).

If you were reareded.

You need to be more specific as to what type of crash this was.