Abstract: This invention is primarily related to a side impact self contained airbag system for a vehicle including a sensor, an inflator, an airbag and, when appropriate, a diagnostic and energy reserve module all within one package. In some implementations, a non-sodium azide propellant is used and the gas in exhausted from the airbag into the door during the accident rather than into the passenger compartment. The preferred implementation uses an all mechanical system but electro-mechanical and electronic sensors can also be used. Several of the improvements disclosed are also applicable for frontal impact airbag systems. A combination of crush sensing and velocity sensing is also disclosed for the all mechanical system.