Narrative:

I was working air carrier X for an ILS approach to runway 23L established on final with air carrier Y approaching from the north for an approach to runway 23R. In trail of both aircraft was air carrier Z on a straight-in approach to runway 23L. I ensured the separation of these aircraft by ensuring vertical separation while adjusting their respective speeds to the appropriate spacing on final. I was concerned with expediting the movement of air traffic to limit their exposure to the icing conditions. I cleared air carrier X for an ILS approach approximately 10 mi from the FAF and instructed him to maintain a speed of 190 KTS or greater to the marker. It appeared that air carrier X was in compliance with my speed restr and I xferred communication of air carrier X to the local control position for landing clearance approximately 5 mi from the FAF. I then issued approach clearance to air carrier Y and restr the pilot to maintain 170 KTS until the marker; which the pilot acknowledged. Subsequently; I issued approach clearance to air carrier Z and the arrival separation appeared to be sufficient. Consequently; after issuing approach clearance to air carrier Z; it appeared that air carrier X incurred a dramatic loss in airspeed immediately following my communication xfer. I made a remark as to this occurrence and my supervisor instructed me to 'break air carrier Y out.' it appeared that air carrier X was now approximately 2 mi from the FAF at a speed of 150 KTS. I immediately canceled the approach clearance for air carrier Y and issued instructions for the pilot to maintain 3000 ft and turn right to a 360 degree heading. An extended period occurred in which air carrier Y descended to slightly below 3000 ft and then climbed to 3300 ft. Then it appeared air carrier Y descended again to 2600 ft while still traveling on the final approach course. I reissued the 360 degree turn to air carrier Y but the pilot did not reply. Subsequently; I again issued a 360 degree heading to air carrier Y and the pilot acknowledged the transmission and commenced his turn. The separation standard for these 2 aircraft was 2 NM lateral. Although a pilot deviation on air carrier X is being investigated; a separation error occurred with the aircraft on final to the parallel runway when 1.79 NM lateral and 700 ft occurred.

Related reports:

Google
 

Original NASA ASRS Text

Title: 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.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.