TRAFFIC ON A SURFACE ROAD CAME TO AN ABRUPT STOP. THE 2004 FORD F150 DID NOT STOP IN TIME AND REAR-ENDED OUR 2003 HONDA PILOT ALONG THE RIGHT HALF OF THE BUMPER. THE IMPACT WAS SEVERE ENOUGH TO SHOVE THE RIGHT FRAME RAIL FORWARD SEVERAL INCHES, WRINKLING THE ROOF AND PUTTING THE DRIVERSIDE REAR DOOR IN TENSION SO THAT IT COULD NOT BE OPENED. THE TWO FRONT SEATS WERE OCCUPIED BY ADULTS. BOTH THE DRIVER'S AND PASSENGER'S SEAT BACKS FAILED. THE DRIVER SUFFERED NO INJURIES, BUT THE PASSENGER SUFFERED BRUISING FROM THE B-PILLAR AND STRAINED BACK FROM THE COLLAPSING SEATBACK.