CARJ CREW; AND ANOTHER SAME MODEL ACFT; OVERSHOT THE LOC WHILE FLYING AN AUTOCOUPLED APCH TO RWY 23 AT BUF.

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THE FOLLOWING DESCRIBES PROBS DISCOVERED WHILE ATTEMPTING TO FLY A COUPLED ILS APCH TO RWY 23 AT BUFFALO NIAGARA INTL ARPT; NEW YORK. 2 CRJ'S WERE INBOUND TO THE ARPT AT THE SAME TIME. I WAS IN THE SECOND ACFT AND WAS THE PNF. IN TRAIL; AT AROUND 4-5 MI; WE WERE BEING GIVEN THE SAME HEADING AND ALT VECTORS AS THE PRECEDING ACFT. LISTENING TO THE APCH CTLR VECTOR THE ACFT IN FRONT OF US; WE HEARD THAT THE VECTOR GIVEN FOR THE LOC INTERCEPT DIDN'T WORK AND THE ACFT WAS GIVEN ANOTHER TO REINTERCEPT. BEING GIVEN THE SAME HEADING ALSO DIDN'T WORK FOR US. WE ALSO NEEDED ANOTHER HEADING VECTOR TO REINTERCEPT THE LOC. AFTER THE LOC WAS INTERCEPTED INBOUND; THE GS CAME ALIVE. JUST PRIOR TO THE IAF; THE GS CTRED AND WAS CAPTURED. THEN THE GS BEGAN TO CLB AND WE GAINED ABOUT 300 FT BEFORE WE DISCONNECTED THE AUTOPLT AND GOT BACK DOWN TO THE INITIAL APCH ALT. WAITING AND WATCHING THE GS INDICATION AS WE WERE TRYING TO DECIDE ABOUT GOING MISSED APCH OR NOT; THE INDICATIONS SETTLED DOWN AND WE CONTINUED THE APCH BY HAND FLYING THE ACFT WITH THE FLT DIRECTOR. AFTER BREAKING OUT AND GETTING A GOOD VISUAL ON THE RWY; WE CONTINUED TO MONITOR THE ILS INDICATIONS UNTIL LNDG. AFTER CLRING THE RWY; WE MADE COMMENTS TO THE TWR CTLR AND FOUND THAT HE WAS ALREADY TAKING NOTES FROM THE FLT THAT WE HAD FOLLOWED IN ON THE APCH. THE FIRST FLT HAD EXPERIENCED THE SAME PROBS WITH THE ILS AS WE DID. IT JUST SO HAPPENED THAT BOTH CREWS WERE ON THE WAY TO THE HOTEL FOR THE OVERNIGHT. I MADE AN EFFORT TO TALK TO THE OTHER CAPT. AFTER SOME CONVERSATION; DISCOVERED THAT BOTH FLTS HAD EXPERIENCED THE IDENTICAL PROBS WITH THE ILS SYS. THEY HAD ALSO ATTEMPTED A COUPLED ILS APCH.