Pyrotechnic fastener seat arrangement for unbelted occupant protection

The invention relates to a vehicle assembly including a seat pan that drops vertically in the event of a frontal impact event to help safeguard against the head of an unbelted seat occupant striking the headliner, windshield or other components of the vehicle. The seat assembly includes a seat pan attached to a seat track. The seat track further includes an attachment bracket. A swing linkage movably connects the seat pan with the seat track by a movable fastener. A slot is formed in the bracket through which at least a part of the movable fastener passes. A pyrotechnic fastener also attaches the swing linkage to the bracket. In a frontal impact event the pyrotechnic fastener is caused to explode thus separating the pyrotechnic fastener into two parts and allowing the swing linkage and its attached seat pan to drop vertically relative to the seat track, thereby lowering the unbelted occupant.