THE TRUCK WAS IN A HEAD-ON COLLISION WITH A LARGE TREE AT FREEWAY SPEEDS. VEHICLE WAS HIT IN CENTER OF BUMPER WITH SUFFICIENT FORCE TO PUSH ENGINE INTO BULKHEAD AND DISTORTING DASHBOARD AND INTERIOR. VEHICLE WAS TOTALED. MY FATHER WAS KILLED IN THE ACCIDENT. POLICE REPORTED HE WAS NOT WEARING A SEAT BELT. OUR CONCERN WAS WHY WASN'T THE AIR BAD DEPLOYED DURING CRASH. THE AIR BAG WARNING LIGHT WAS NOT ILLUMINATED SHORTLY BEFORE THE CRASH. *AK