Belt pretensioning systems are more and more prevalent in todays vehicles and their contribution will inaccident statistics positively.

Current developments are using test procedures and requirements not reflecting real life situations regarding slack. Field studies show that most occupants have a huge amount of slack in their belt system during normal operation.

Belt slack has a big influence on the performance of restraint systems and can therefore not be ignored in dynamic laboratory tests.

This paper proposes an improved test method with standardized slack, in order to make systems comparable and show customers the real advantages of pretensioning.