ON INST APCH; ACR HAS LTSS.

Narrative

APPARENT INACCURATE POS RPTING ON THE PART OF THE CONFLICTING ACFT TO SPN TWR. ALSO; I SUSPECT THAT THE CONFLICTING ACFT'S XPONDER WAS INAPPROPRIATELY ARMED IN ORDER TO AFFECT TCASII DETECTION BY OUR ACFT. CONFLICTING ACFT WAS ASKED ITS POS BY SPN TWR. '5.8 DME' WAS THE REPLY; AS I RECALL. WE WERE ARRIVING AT 6 DME. MY FO THEN WAS THE FIRST OF US TO GET A VISUAL ON OTHER ACFT. THE SO WAS NEXT TO GET A VISUAL ON HIM. CONFLICTING ACFT WAS AT CO-ALT AND CONVERGING. A L TURN AWAY FROM THE CONVERGENCE WAS INITIATED BY OUR FLT. I WAS TRYING TO GET TCASII ADVISORY OF THE CONFLICTING ACFT. OUR TCASII WAS PROPERLY ARMED IN TA/RA MODE. WX RADAR WAS BEING USED BY US. I DID GET A PRIMARY TARGET ON THE SCREEN WITHOUT AN RA OR A TA. BY THIS TIME I HAD A GOOD VISUAL CONTACT WITH CONVERGING ACFT. A DIVERGING CONDITION HAD BY THIS TIME BEEN ESTABLISHED. OUR APCH; LNDG; AND PARKING WAS THEN ROUTINELY COMPLETED. CONFLICTING ACFT MADE A R-HAND 360 DEG TURN IN ORDER TO COMPLETE HIS APCH AND LNDG AS #2. OUR FLT WAS PROPERLY CLRED FOR AN INST APCH.