System and method for reacting to an expected impact involving a vehicle including an anticipatory sensor system for determining that an impact involving the vehicle is about to occur prior to the impact and an impact responsive system coupled to the sensor system and actuated after its determination of the expected impact. The sensor system includes wave receivers spaced apart from one another, each receiving waves generated by, modified by, or reflected from a common object exterior of the vehicle. The impact responsive system attempts to reduce the potential harm resulting from the impact and can be a protection apparatus which protects a vehicular occupant or a pedestrian, such as one including an airbag and an inflator for inflating the airbag.