IND TRACON CTLR EXPERIENCED OPERROR AT 2700 FT WITH TFC ON PARALLEL RWY AND POSSIBLY WITH FOLLOWING TFC ON ILS FOR RWY 23L.

Narrative

I WAS WORKING ACR X FOR AN ILS APCH TO RWY 23L ESTABLISHED ON FINAL WITH ACR Y APCHING FROM THE N FOR AN APCH TO RWY 23R. IN TRAIL OF BOTH ACFT WAS ACR Z ON A STRAIGHT-IN APCH TO RWY 23L. I ENSURED THE SEPARATION OF THESE ACFT BY ENSURING VERT SEPARATION WHILE ADJUSTING THEIR RESPECTIVE SPDS TO THE APPROPRIATE SPACING ON FINAL. I WAS CONCERNED WITH EXPEDITING THE MOVEMENT OF AIR TFC TO LIMIT THEIR EXPOSURE TO THE ICING CONDITIONS. I CLRED ACR X FOR AN ILS APCH APPROX 10 MI FROM THE FAF AND INSTRUCTED HIM TO MAINTAIN A SPD OF 190 KTS OR GREATER TO THE MARKER. IT APPEARED THAT ACR X WAS IN COMPLIANCE WITH MY SPD RESTR AND I XFERRED COM OF ACR X TO THE LCL CTL POS FOR LNDG CLRNC APPROX 5 MI FROM THE FAF. I THEN ISSUED APCH CLRNC TO ACR Y AND RESTR THE PLT TO MAINTAIN 170 KTS UNTIL THE MARKER; WHICH THE PLT ACKNOWLEDGED. SUBSEQUENTLY; I ISSUED APCH CLRNC TO ACR Z AND THE ARR SEPARATION APPEARED TO BE SUFFICIENT. CONSEQUENTLY; AFTER ISSUING APCH CLRNC TO ACR Z; IT APPEARED THAT ACR X INCURRED A DRAMATIC LOSS IN AIRSPD IMMEDIATELY FOLLOWING MY COM XFER. I MADE A REMARK AS TO THIS OCCURRENCE AND MY SUPVR INSTRUCTED ME TO 'BREAK ACR Y OUT.' IT APPEARED THAT ACR X WAS NOW APPROX 2 MI FROM THE FAF AT A SPD OF 150 KTS. I IMMEDIATELY CANCELED THE APCH CLRNC FOR ACR Y AND ISSUED INSTRUCTIONS FOR THE PLT TO MAINTAIN 3000 FT AND TURN R TO A 360 DEG HDG. AN EXTENDED PERIOD OCCURRED IN WHICH ACR Y DSNDED TO SLIGHTLY BELOW 3000 FT AND THEN CLBED TO 3300 FT. THEN IT APPEARED ACR Y DSNDED AGAIN TO 2600 FT WHILE STILL TRAVELING ON THE FINAL APCH COURSE. I REISSUED THE 360 DEG TURN TO ACR Y BUT THE PLT DID NOT REPLY. SUBSEQUENTLY; I AGAIN ISSUED A 360 DEG HDG TO ACR Y AND THE PLT ACKNOWLEDGED THE XMISSION AND COMMENCED HIS TURN. THE SEPARATION STANDARD FOR THESE 2 ACFT WAS 2 NM LATERAL. ALTHOUGH A PLTDEV ON ACR X IS BEING INVESTIGATED; A SEPARATION ERROR OCCURRED WITH THE ACFT ON FINAL TO THE PARALLEL RWY WHEN 1.79 NM LATERAL AND 700 FT OCCURRED.