THE PILOT OBTAINED A BRIEFING FROM THE FAA FLIGHT SERVICE STATION PRIOR TO HIS PLANNED FLIGHT. THE BRIEFER, IN PART, TOLD THE PILOT THAT MOUNTAIN OBSCURATIONS WERE FORECAST FOR CALIFORNIA. THE PILOT AND HIS 4 PASSENGERS DEPARTED ON THEIR PLANNED CROSS COUNTRY FLIGHT. THE AIRPLANE AND ITS OCCUPANTS DID NOT RETURN ON TIME AND FAMILY MEMBERS REPORTED THEM MISSING TO THE AUTHORITIES. A SEARCH WAS INITIATED, BUT WAS CALLED OFF THE NIGHT OF THE ACCIDENT DUE TO ADVERSE WEATHER. AFTER THREE WEEKS, THE OFFICIAL SEARCH WAS TERMINATED. THE PILOT'S FATHER CONTINUED THE SEARCH AND LOCATED THE DOWNED AIRPLANE WRECKAGE AT ABOUT THE 7,000 FOOT LEVEL OF A MOUNTAIN ABOUT 8 MONTHS AFTER IT WAS REPORTED MISSING. WITNESSES LOCATED NEAR THE ACCIDENT SITE THE NIGHT OF THE ACCIDENT, REPORTED THE MOUNTAINS WERE OBSCURED FROM ABOUT THE 4,000 FOOT LEVEL UP TO THEIR RESPECTIVE TOPS. THEY ALSO REPORTED 'HEAVY' SNOW IN THE AREA THE NIGHT OF THE ACCIDENT. THE PILOT HAD LESS THAN ONE HOUR TOTAL INSTRUMENT FLIGHT TIME AND ABOUT 9 HOURS OF SIMULATED INSTRUMENT TIME.