EMPLOYEE WAS ATTEMPTING TO MOUNT THE 777D ROCK TRUCK. HE PLACED HIS LUNCH BOX ON THE BUMPER, THEN CLIMBED TO THE BUMPER. WHEN HE TRIED TO PLACE HIS LUNCH BOX ON THE CATWALK. HE DROPPED HIS BU CKET. WHILE ATTEPTING TO CATCH THE LUNCH BOX, HE SLIPPED AND FELL TO THE GROUND.