BFR TKOF, THE PLT FILED A VFR FLT PLAN & RCVD A WX BRIEFING WHICH INCLUDED AN AIRMET. THE AIRMET CONTAINED PRECAUTIONARY INFO ABT INSTRUMENT CONDS (IMC), ICING & MTN OBSCURATION IN CALIF. WHEN THE PLT OPENED HIS FLT PLAN WITH THE FSS, HE WAS AGAIN BRIEFED ON THE AIRMET. DRG FLT, THE ACFT IMPACTED STEEP/RISING TRRN ON THE NE SLOPE OF MT HARDWOOD AT AN ELEV OF APRX 8750'. THE PLT HAD PLANNED FOR FLT ALONG PUBLISHED AIRWAYS & FILED TO CRUISE AT 8500' MSL. FOR FLT IN THE VCNTY OF THE ACDNT, HE HAD FILED TO FOLL0W V-394 FM DAGGET TO APLES INTXN (HDG 214 DEG), THEN TO TURN & F0LLOW V-442 TO PARADISE (HDG 192 DEG). HOWEVER, AFTER REACHING APLES INTXN, THE ACFT DID NOT CHANGE COURSE, BUT CONTD IN THE SAME DRCTN (AS IF CONTG ON V-394). ABT 21 MI BYD APLES INTXN, IT CRASHED. FOR INSTRUMENT FLT NR THE CRASH SITE, THE MIN EN ROUTE ALT ON V-394 WAS 11,500'. THE PLT HAD RECENTLY TAKEN FLT TRAINING IN PREPARATION FOR AN INSTRUMENT RATING. THE ELT HAD ACTIVATED, BUT AERIAL SEARCH & RESCUE OPNS WERE NOT PSBL ON THE DAY OF THE ACDNT DUE TO IMC WX IN THE MTNS.