CARJ FLT CREW LNDG BUF EXPERIENCED ERRATIC GS RECEPTION DURING INTERCEPT FOR ILS RWY 23.

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PRIOR TO APCH AT RWY 23 IN BUF; I DISCUSSED WITH MY FO THAT MANY TIMES I HAVE RECEIVED A FALSE GS ON THE ILS RWY 23. HE SAID HE WAS AWARE OF THE PROB. THE WX WAS FOGGY AND THE RVR WAS GOING UP AND DOWN BTWN 1800 FT AND 2000 FT. WE WERE VECTORED FOR THE APCH AND GIVEN 2300 FT AND A HDG TO INTERCEPT THE LOC; CLRED FOR THE APCH. IT WAS KIND OF A LATE TURN FOR THE LOC; BUT THE APCH WAS ARMED AND CAPTURED THE LOC AND GS ALMOST AT THE SAME TIME. IMMEDIATELY THE GS STARTED MOVING UP AND THE ACFT BEGAN A CLB. MY FO DISCONNECTED THE AUTOPLT AND MADE THE CORRECTIONS TO DSND BACK DOWN TO 2300 FT. WE WERE STILL OUTSIDE THE OM AND DECIDED WE WOULD TRY TO GET RE-ESTABLISHED ON A STABILIZED APCH. IF WE COULD NOT; PRIOR TO THE OM; WE COULD GO MISSED. WE GOT BACK TO OUR ASSIGNED ALT AND WE WERE ABLE TO MAKE A STABILIZED APCH TO LNDG. I INFORMED THE APCH CTLR OF OUR DEV AND THE REASON. I ALSO TALKED TO THE TWR CTLR ABOUT THE PROB. I CALLED THE SUPVR AND SHE TOLD ME THAT THERE IS A NOTAM ABOUT THE GS. SHE FAXED IT TO ME. IT HAS BEEN LIKE THIS FOR YRS! I HAVE HAD THIS PROB MANY TIMES. THIS GS NEEDS TO BE FIXED! OR MAYBE THEY SHOULD NOT USE A R DOWNWIND; SINCE IT ONLY HAPPENS ON THE R DOWNWIND FOR RWY 23.