An airbag system (100) for an automobile comprises sensors (110) mounted on a frame member of a vehicle frame for detecting a crash by sequentially measuring stress wave cause by the crash; an electronic control unit (120) for outputting an actuation signal based on outputs from the sensors; an inflator (130) for generating a gas in response to the actuation signal; and an airbag (140) operatively coupled to the inflator and being deployed by supply of the gas generated from the inflator. The sensors are mounted on the frame member at predetermined intervals in a path, along which the stress waves propagate through the frame member. The electronic control unit outputs the actuation signal when each output from each sensor exceeds a predetermined threshold. The airbag system can remarkably reduce the time required for detecting a crash by measuring the stress waves, which propagate very rapidly through the vehicle frame, thereby deploying the airbag in a timely manner. The invention also extends to a method of operating the airbag system.