FAR VIOLATION.

Narrative

I FLY FOR AN FAR 135 FREIGHT OPERATOR. THE FREIGHT I WAS SUPPOSED TO DELIVER WAS LATE DUE TO IFR WX. BECAUSE OF THIS; I HAD TO FLY THE FREIGHT TO PORTLAND; OR; INSTEAD OF OAKLAND; CA.I WAS SUPPOSED TO STAY IN PORTLAND AND GET MY REQUIRED REST AND THEN RETURN TO OAKLAND ON AN FAR 91 LEG. THE WX AT MY ETA WAS FORECAST TO BE LOW CEILINGS AND VISIBILITIES (MY ORIGINAL DESTINATION WAS SAC). IN ADDITION; THE NIGHT BEFORE OAK (MY ALTERNATE) EXPERIENCED LOW CEILINGS AND VISIBILITIES. I EXPECTED THAT THIS UNUSUALLY THICK FOG COULD BE PRESENT WHEN I WAS EXPECTED TO RETURN. I CALLED FOR A WX BRIEFING EARLY TO DETERMINE WHAT I WAS UP AGAINST. THE FORECAST WAS FOR THE SAC VALLEY AND OAK VICINITY TO BE DETERIORATING OR HAVE ALREADY DETERIORATED AT MY ETA. I FELT RESTED AT THE TIME AND DECIDED TO DEPART EARLY SO THAT I WOULD AVOID ANY PROBS WITH WX. I ALSO WANTED TO DEPART EARLY BECAUSE I WAS SCHEDULED TO FLY ANOTHER 3 HRS AS SOON AS I RETURNED FROM PDX. I FELT THAT IT WOULD BE EASIER FOR ME TO GET TO SAC AND GET A COUPLE HRS OF REST AND THEN FLY AGAIN RATHER THAN IMMEDIATELY TURNING AROUND AND FLYING ANOTHER 3 HRS. IN CONCLUSION; I LEFT EARLY TO AVOID DEALING WITH VERY LOW CEILINGS AND VISIBILITIES AND BECAUSE I THOUGHT IT WOULD BE EASIER ON MY BODY TO DO SO. I DID THIS BECAUSE I THOUGHT IT WAS THE SAFEST COURSE OF ACTION. I DON'T KNOW WHAT COULD BE DONE SO THAT THIS WON'T HAPPEN AGAIN. I FELT THAT I TOOK THE SAFEST PATH. IF MORE LEEWAY IS GIVEN TO REST REQUIREMENTS; I'M SURE THAT COMPANIES WILL ABUSE THIS. I FEEL THAT THE CURRENT REST REQUIREMENTS ARE FAIR. EXCEPT THAT AFTER A NUMBER OF DAYS AND AFTER WORKING IRREGULAR HRS; THE WORK STILL BECOMES RATHER FATIGUING. I DO FEEL THAT FATIGUE STUDIES DO HAVE TO CONTINUE AND; MOST IMPORTANTLY; THAT THE FAA USES THE INFO GAINED FROM THESE STUDIES. NOTE: I HAD FLOWN APPROX 60 HRS DURING THE MONTH PRIOR TO THIS EVENT.