ACR X HAD LTSS FROM SMT Y. SYS ERROR. TCASII TA RA.

Narrative

I WAS INVOLVED IN AN OPERROR ON NOV/WED/91. AT THE TIME THE ERROR OCCURRED MY ATTN WAS DIVERTED TO A LOST ACFT THAT I WAS TRYING TO VECTOR TO AN ARPT IN MY AIRSPACE. ACR X WAS GIVEN A DSCNT TO 2000 AND A VECTOR OF 070 DEGS AND TOLD TO RPT THE ARPT IN SIGHT. SMT Y WAS BEING VECTORED TO A SECOND PRACTICE APCH; I ASSUMED THIS ACFT WAS VFR ON PRACTICE APCHS; AND WANTED AN IFR CLRNC TO THE ISLIP ARPT AFTER HE FINISHED. I HAD A THIRD ACFT ON APCH TO ANOTHER ARPT; WHICH TOOK MORE OF MY ATTN. I WAS AGAIN DIVERTED TO THE LOST ACFT. ACR X ADVISED ME THAT HE HAD AN ACFT AT HIS 10 O'CLOCK POS 4 MI; AND I THEN ISSUED A 180 DEG HDG. HE ADVISED THAT TCASII WAS TELLING HIM TO CLB; I ROGERED HIS XMISSION. I SOON AFTER CLRED ACR X FOR AN ILS APCH. I LATER WAS RELIEVED AND INFORMED MY SUPVR OF THE INCIDENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE SUPVR WAS AT THE POS TO PROVIDE ASSISTANCE WITH THE LOST ACFT. CONFLICT ALERT HAD ACTIVATED BTWN ACR X AND SMT Y. WHEN THE RPTR TURNED ACR X SEPARATION REDUCED TO 1.6 MI AND 200 FT. ACR X HAD A TCASII RA AND CLBED 300 FT. THE RPTR SAID HE SHOULD HAVE KNOWN SMT Y WAS IFR BECAUSE THE DATA TAG DID NOT HAVE A V INDICATING THE ACFT WAS VFR.