Our aim is to show that today's safety standards (FMVSS 208, EC-Proposals) are inadequate in the present state to ensure optimum protection for belted passengers. These standards do not take into account motion sequence during impact. The postulated tolerance limits - HIC, SI, forward displacements etc. - cannot describe the dynamic behaviour adequately.

We emphasize the importance of motion sequence to ensure optimum biomechanic conditions, because motion sequence is the necessary prerequisite for any discussion about biomechanical tolerance limits.

First results of our current belt-accident investigations indicate that this is an important problem. By applying experience from crash tests and accident investigations, we try to define simple and well-controllable criteria for motion sequence. These criteria should not only guarantee favourable biomechanical loads for the belt-restrained passenger, but also give the possibility of simplifying data registration and calculation of results.

Our final aim is to reduce belt-specific injuries, since they are avoidable by using current technical capability.

The solution of these problems can be achieved by modifications of safety standards using defined motion sequence criteria. This would lead to further developments of the system comprising a 3-point-belt and the seat.

In this paper we introduce one possible development. Results of a number of crash tests show its efficiency.