Why are people still dying in frontal crashes despite seat belt use, air bags, and the crashworthy structures of late-model vehicles? Statistical analyses show the combination of seat belt use and air bags is highly effective, reducing fatality risk by 61 percent compared to an unbelted occupant of a vehicle not equipped with air bags – but 61 percent is not 100 percent. To address the question, an interdisciplinary NHTSA team reviewed every case of a frontal fatality to a belted driver or right-front passenger in a model year 2000 or newer vehicle in the Crashworthiness Data System (CDS) of the National Automotive Sampling System through calendar year 2007. Aside from a substantial proportion of these 122 crashes that are just exceedingly severe, the main reason people are still dying is because so many crashes involve poor structural engagement between the vehicle and its collision partner:​ corner impacts, oblique crashes, impacts with narrow objects, and underrides. By contrast, few if any of these 122 fatal crashes were fullfrontal or offset-frontal impacts with good structural engagement, unless the crashes were of extreme severity or the occupants exceptionally vulnerable