B727 ACFT ON NDB APCH WITH 600 FT CEILING; HAD ERRATIC NDB READINGS AND WASN'T IN POS TO LAND ON INTENDED RWY. FLC LANDED ON RECIPROCAL RWY.

Narrative

ON FLT FROM DAY-BRO; ON ARR; WX WAS RPTED AT 4V6 OVCST 6BR. ILS RWY 13R WAS NOTAMED OTS AND THE LCL ATIS ALSO CONFIRMED THIS. I WAS BEING VECTORED FOR THE NDB APCH TO RWY 13R; BUT EVEN AT 15 MI FROM THE STATION WE HAD TROUBLE PICKING UP A CLR IDENT. THE NEEDLES DID POINT IN THE GENERAL DIRECTION; BUT THEY WERE WAVERING. AT APPROX 6 MI FROM THE MARKER ON A 160 DEG HDG; I WAS CLRED FOR THE APCH. AS I PASSED OVER THE STATION; BOTH NEEDLES SWUNG TO MY L BUT THEY WERE SPLIT. AFTER STATION PASSAGE I HELD WHAT I HAD. THEN I 'DRAGGED THE TAIL' OF THE NEEDLE TO WHAT I THOUGHT WOULD HOLD THE COURSE; HOWEVER; IT BECAME VERY ERRATIC. I DID BREAK OUT AT APPROX 600 FT TO THE R OF THE RWY; BUT NOT IN A POS TO LAND ON RWY 13R. AS THE WIND WAS LIGHT AND VARIABLE AND THE RWY IN SIGHT; I ELECTED TO LAND ON RWY 31L WITH NO FURTHER PROBS. THE REASON I AM RPTING THIS FLT IS THAT I AM NOT IN THE HABIT OF MAKING LOW ARPT PATTERNS WITH A B727 AND I QUESTION THE RELIABILITY OF THIS PARTICULAR NDB APCH. I ALSO MENTIONED THIS TO THE LCL ARPT MGMNT.