C421 MADE VOR APCH BELOW APCH MINIMA THEN CIRCLED TO LAND AND MADE MISSED APCH.

Narrative

A TWIN CESSNA ON THE VOR 6 APCH; IN SOLID IFR CONDITIONS; RPTED OVERSHOOTING THE APCH. THE ACFT WAS CLRED TO LAND; BUT WAS NOT INSIGHT. THE ACFT (C421) WAS SPOTTED MID RWY AT LOWER LEVEL; APPROX 75 FT. THE PLT THEN INFORMED THE LCL CTLR THAT HE WOULD BE MAKING A L TURN AND CIRCLE BACK TO LAND. THE LCL CTLR INFORMED THE PLT THAT THERE ARE HILLS IN THAT DIRECTION; AND SUGGESTED THE PLT TURN R. THE PLT CLAIMED TO HAVE THE RWY INSIGHT AND MADE A L TURN INTO THE CLOUDS; OUT OF SIGHT OF THE TWR. THE PLT BEGAN FLYING AT BELOW 150 FT AGL AROUND THE ARPT FOR ABOUT 1 MIN AND FINALLY DECIDED TO EXECUTE A MISSED APCH. CIRCLING MINIMUMS AT NAPA ARE 600 FT AND LNDG MINIMUMS FOR A STRAIGHT IN RWY 6 ARE 420 FT. THE PLT DISPLAYED INCREDIBLY BAD JUDGEMENT FLYING LOW LEVEL OVER THE TERMINAL BUILDING; A RESTAURANT; CHP BUILDING AND SEVERAL HANGARS. THE TWR RECEIVED SEVERAL COMPLAINTS FROM THE CHP; AND OTHERS ON THE FIELD AT THE TIME OF THIS OCCURRENCE. THE WX AT THIS TIME WAS INDEFINITE 200 FT SKY OBSCURED 3/4 MI VISIBILITY. THIS SIT COULD HAVE BEEN AVOIDED IF THE PLT WAS MORE FAMILIAR WITH THE APCH; ESPECIALLY THE LNDG MINIMUMS. THE CTLR ALSO COULD HAVE HELPED BY TELLING THE PLT TO EXECUTE THE MISSED APCH WHEN INFORMED THAT THE PLT OVERSHOT THE APCH.