A C182 PLT; ON AN ILS TO STS; EXECUTED A MISSED APCH; CITING GS INACCURACY AS THE REASON.

Narrative

ON JAN/SUN/02; THE PIC WAS ON A RETURN FLT FROM SMX; CA; TO HOME BASE STS; CA; UNDER FLT FOLLOWING WITH BOTH ZLA AND ZOA. THE FLT WAS UNEVENTFUL UNTIL THE PIC CHKED THE TERMINAL WX AT STS AND DETERMINED THAT THE VISIBILITY WAS 2.5 MI AND THE CEILING WAS 400 FT AGL. ACCORDINGLY; AFTER BEING PASSED OFF FROM BAY APCH TO ZOA; THE PIC REQUESTED AN ILS APCH INTO STS. WHILE ON THE APCH; IT APPEARED EVERYTHING WAS NORMAL AND THE PIC PROCEEDED ON THE LOC DOWN THE GS AND AS THE APCH WAS MADE TO THE ARPT; THE RWY OR RWY LIGHTING; INCLUDING APCH LIGHTS DID NOT COME IN VIEW. THE PIC HAD PASSED THE ARPT; HOWEVER; WAS IN VISUAL OF THE GND WHEN HE BEGAN THE MISSED APCH PROC AND WAS ADVISED BY THE TWR TO CONTACT CTR. THE PIC WAS ADVISED THAT HE WAS AT 500 FT AGL WHEN HE PASSED OVER THE RWY EVEN THOUGH THE GS INDICATED THAT THE ACFT WAS ON THE CORRECT FLT PATH. AFTER THE MISSED APCH; THE PIC REQUESTED AN ADDITIONAL APCH WHICH WAS GRANTED AND ON THE SECOND APCH THE RWY WAS IDENTIFIED AND A LNDG WAS MADE. AS A FOLLOW-UP; THE PIC DISCUSSED THE MATTER WITH BOTH CTR AND LATER WITH THE TWR MGR AND WAS TOLD NO FURTHER ACTION WOULD BE TAKEN. THE PIC WAS CONCERNED ABOUT THE PERFORMANCE OF THE GS INST AND HAD IT CHKED AND SUBSEQUENTLY ADJUSTED TO BRING IT INTO CONFORMANCE WITH A SET GS SIGNAL. APPARENTLY THE REASON THE FIRST APCH WAS HIGH WAS DUE TO THE INACCURACY OF THE IN PLANE INST.