Only about 150 milliseconds are decisive on whether an accident leads to heavy injuries or even death or not. In case of an accident the air bag must act synchronically with the movement of the passenger and collapse when the actual impact is over, not to hinder the passenger or rescue helpers.
At least two acceleration sensors submit a crossing of the preset deceleration movement to the control device, in this case caused by a frontal impact of the vehicle. Should the driver be prevented from hitting the steering wheel, the air bag must be triggered within 15 milliseconds and be unfolded fully within another 35 milliseconds. The safety belts and the seatbelt tensioners are important. The vehicle dips down in front and raises for the passengers the vehemence of the impact.
All this happens so violently that parts of the air bag system are heated by the quick air intake duct. Sometimes, passengers suffer light fire injuries after an air bag release. Therefore, it is especially important that the air bag does not release unless in real case of need. In the meantime, systems have been developed that can be switched off, e.g., for the front passenger seat. Alternatively, there may be an intelligent recognition system of the seat configuration. 08/10