AN A319 RA1 AND RA2 FAULT ON FINAL TO SJC RWY 30L CAUSED AN AUTOPILOT DISCONNECT AND REVERSION TO DIRECT LAW. SAME OCCURRENCE AT SAME LOCATION PREVIOUSLY.

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WE WERE DOING A MANAGED VOR TO RWY 30L (FOR PRACTICE; IT WAS VMC). THE COURSE IS OFFSET FROM THE LOC BY ABOUT 5 DEGS; I AM GUESSING; SO YOU COME RIGHT OVER THE CITY. WHILE WE WERE ON SHORT FINAL WE HAD AN RA1 AND RA2 FAULT AND THE REVERSION TO DIRECT LAW (NO INDICATIONS EXCEPT THE AUTOPLT DISCONNECTED ON ITS OWN; USE MAN PITCH TRIM ON THE PFD AND CONFIGN 3 ON THE ECAM IND MEMO). AS SOON AS WE LANDED THE FAULTS WENT AWAY. ALL THAT WAS LEFT WAS THE FLT CTL CLASS 2 MAINT MESSAGE. I HAVE NEVER HAD AN RA1 FAULT GOING INTO SJC BUT HAVE HAD MANY RA2 FAULTS. THEY ALL SEEM TO HAPPEN ABOUT THE SAME PLACE WHEN LNDG ON RWY 30L. I DON'T GO IN THERE VERY OFTEN DURING DAYLIGHT OPS BUT FROM WHAT I CAN TELL THERE IS NO REAL UNUSUAL TERRAIN; HOWEVER; IT IS USUALLY RIGHT AROUND THE SPORTS ARENA. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THAT ANOTHER ACR WAS EXPERIENCING THE SAME FAULT AT CERTAIN LOCATIONS AND IS WORKING WITH THE ACFT MFG TO SOLVE THE PROBLEM. THE ISSUE APPARENTLY IS CERTAIN ACFT MODELS HAVE A TYPE OF RADIO ALTIMETER THAT IS AFFECTED BY TERRAIN CHARACTERISTICS. NON ONLY DOES THIS RADIO ALTIMETER REACT TO TERRAIN FEATURES SIMILAR TO THAT ON THE SJC APCH BUT APPARENTLY IT ALSO REACTS WHEN TRANSITIONING FROM WATER TO LAND ON FINAL APCH.