A DC9-30 CAPTURED A FALSE GS APCHING BUF RWY 23 FROM R OF COURSE.

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ILS RWY 23 APCH VECTORED AT 2300 FT. APPROX 800 FT OVCST; 2 MI VISIBILITY. NOTE BRIEFED ON APCH THAT THE 'GS UNUSABLE FROM R.' VECTORED FROM R ON INTERCEPT HDG. NO DME ON LOC. BOTH CAPT AND FO ON ILS FREQ DUE TO PROCS TO ENSURE GOOD SIGNAL. TURNED ON LOC AND CLRED FOR APCH FROM A POINT I GUESSED WOULD BE VERY CLOSE TO ADF OM AT AN ALT THAT SHOULD INTERCEPT GS PRIOR TO ADF. LOC STARTED COMING ACROSS AND LOC CAPTURE LIGHT ILLUMINATED AND I CALLED IT. THE AUTOPLT INTERCEPTED THE GS AT A POINT THAT I THOUGHT WAS ACCEPTABLE AS WE WERE NEAR THE LOC. THE DSCNT RATE OF THE AUTOPLT INCREASED AT AN UNUSUAL RATE AND WHAT I THOUGHT WAS THE NEEDLE SWING OF ADF MARKER PASSAGE WAS ACTUALLY THE NEEDLE MOVING WITH THE CARD AS WE INTERCEPTED THE LOC. ABOUT THAT TIME I SENSED SOMETHING WAS NOT RIGHT. A FALSE GS CAPTURE WAS NOT SUSPECTED AT THAT MOMENT BUT I KNEW SOMETHING WAS WRONG; AS WE HAD NOT PASSED THE MARKER YET. I TURNED AUTOPLT OFF AND LEVELED ABOUT 500 FT BELOW ASSIGNED ALT JUST AS THE FORMERLY CAPTURED LOC WENT FULL L ON THE HSI. AT THAT MOMENT; APCH QUESTIONED OUR ALT AND MENTIONED FALSE GS PROBS FROM R SIDE. CLBED BACK TO 2300 FT AND RE-INTERCEPTED LOC AND GS FOR A SUCCESSFUL LNDG. THIS APCH IS A BIG TRAP AND THE FO AND I BOTH INTERPED THE APCH NOTE THAT IF WE DID HAVE A PROB IT WOULD JUST BE 'NO' GS NOT A FALSE ONE. OUR NON-GLASS ACFT WITH NO DME ON APCH AND A FALSE LOC (ALSO WITH NO FLAGS SHOWING) ARE BIG FACTORS. FROM NOW ON; I WILL HAVE THE PNF TUNE ANY DME THAT CAN HELP WITH POS AND REALIZE THAT A NOTE ON 'GS UNUSABLE' COULD MEAN A FALSE GS. ALSO; OUR TRAINED PROC TO ALWAYS SELECT AUTO APCH ON AUTOPLT WHEN CLRED FOR APCH MAY NOT ALWAYS BE APPROPRIATE. THIS BUF APCH NEEDS TO BE FIXED. ONE OTHER FACTOR MIGHT BE THAT I HAVE BEEN OFF THE DC9 FOR APPROX 14 MONTHS AND JUST RE-QUALIFIED ON DC9 AND HAVE FLOWN ONLY 3 TRIPS WHEN THIS HAPPENED.