EMPLOYEE WAS A PASSENGER IN A PICK-UP DOING PRE-PM INSPECTIONS. THEY ENCOUNTERED WHITE OUT CONDITIONS. THE DRIVER TRIED TO STOP THE TRUCK BUT IT SLID INTO A CRUSHED ROCKPILE DUE TO SLIPPERY CO NDITIONS. PASSENGER WAS WEARING A SEATBELT - WAS JOSTLED AROUND AND COMPLAINED OF NECK PAIN. HE STARTED CHIROPRACTIC TREATMENTS ON 12/19/03.