WHILE STATIONARY IN MY 1991 FORD RANGER EXTENDED CAB PICKUP WITH THE SEAT BELT BUCKELED I ENDURED A 50+ MPH REAR END COLLISION. THE MOMENTUM OF THE COLLISION THREW ME FORWARD AND AS I RECOILED BACK AGAINST THE SEAT, THE SEAT COLLAPSED AND ALLOWED ME TO BE THROWN BACKWARDS WITH SUCH FORCE AS TO BREAK THE REAR WINDOW WITH MY HEAD.