ACR TRACK DEVIATION FROM 095 DEGREE RADIAL INTO SFO DUE TO EXPECTATION OF VISUAL APCH CLRNC.

Narrative

CLRED INBND TO SFO ON THE SFO 095 DEG R. AS WE CONTINUED INBND APCH CTL INQUIRED IF WE WERE STILL ON THE 095 DEG R. I IMMEDIATELY ANSWERED YES; HOWEVER I THEN NOTICED WE WERE 1/2 DOT DEFLECTION LEFT OF COURSE. DUE TO OUR PROX TO SFO VOR AND THE CLOSENESS OF ALIGNMENT BTWN THE 095 DEG R AND THE 28R LOC I CAN SEE THE REASON FOR CONCERN. AFTER CHKING MY OWN RADIO TO VERIFY COURSE AND FREQ I GLANCED TO CHK WHAT THE PF HAD TUNED IN. AT THE TIME I OBSERVED HIS RADIOS. HE HAD THE 095 DEG R OF SFO TUNED AND WAS CORRECTING. THE LOC 28R WAS DIALED ON HIS #2 RADIO AND I DO NOT KNOW IF AT THE TIME APCH QUESTIONED US IF HE WAS FLYING THE LOC OR NOT. IT WOULD TAKE THE OTHER PLT JUST AN INSTANT TO SWITCH RADIOS BACK WHILE I WAS CONFIRMING MY OWN. AFTER CORRECTING BACK WE WERE SHORTLY THEREAFTER CLRED FOR THE VISUAL APCH AND PROCEEDED INBND W/O INCIDENT. POSSIBLE EXPLANATION: WE WERE PAST THE POINT WHERE ONE WOULD NORMALLY RECEIVE THE VIS APCH CLRNC. WE WERE OBVIOUSLY IN LINE AND SEQUENCED AND KNEW THAT AT ANY MOMENT A VIS APCH WOULD BE GIVEN. HOWEVER; OUR CLRNC WAS THE 095 DEG R AND; REGARDLESS; THAT IS WHERE WE SHOULD HAVE BEEN. I WAS WATCHING FOR TFC AND DID NOT NOTICE THE COURSE DEV TILL APCH CONTACTED US. EVEN IF I HAD BEEN WATCHING MY VOR CLOSER I PROBABLY WOULDN'T HAVE FELT VERY ALARMED BY A 1/2 DOT DEFLECTION. I FEEL THE SFO ARRS NORMALLY WORK VERY WELL AND THIS WAS POSSIBLY AN INSTANCE OF A PLT EXPECTING A CLRNC; KNOWING WHAT THAT CLRNC WILL BE; AND SLOWLY; UNINTENTIONALLY DRIFTING OVER TO LINE UP WITH THE RWY. ALL OF THIS; OF COURSE; IS CONTRARY TO TRNING; ACTUAL PRACTICE AND GOOD COMMON SENSE; BUT IS A NORMAL HUMAN REACTION. HOWEVER; WE CAN'T FLY CLRNCS WE 'KNOW' OR 'EXPECT TO GET ANY MOMENT. IT'S UNFORTUNATE THAT THE INBND RADIAL AND 28R LOC ARE SO CLOSE THAT EVEN A SMALL DEV CAN CAUSE A PROB. BUT IN THIS CASE; THAT IS NOT THE PROB--WE SHOULD HAVE BEEN ON THE 095 DEG R AND IF THERE WAS ANY DEV COMMON SENSE WOULD SAY; 'BE OFF COURSE ON THE OTHER SIDE IF YOU MUST BE OFF COURSE AT ALL.'