Narrative:

We had just switched from a north flow operation to a south flow operation due to a wind shift associated with an area of heavy precipitation southwest of the airport. Soon after the switch; I took a handoff on a heavy A300; approaching the field from the west. The A300 appeared to be navigating directly to the FAF from the feeder as visual approaches were working well. The A300 was following another heavy aircraft to runway 17R with multiple aircraft landing the parallel runway. The A300 had a significant overtake on the aircraft that he was following so I instructed him the reduce speed at 030. Shortly after issuing the speed reduction; I issued traffic to the A300 informing him of the traffic that he was to follow. The pilot stated that he had traffic at his 12 o'clock but it was unclear whether he had the traffic to follow in sight or the aircraft on final for the parallel runway. I then asked him if he had the airport in sight as an ILS approach was not an option from his position. The A300 reported the field in sight and I gave him a 30 degree turn to final and cleared the aircraft for the visual approach to runway 17R. At this point the A300 was more than 4 miles in trail of the heavy aircraft that he was following and I assumed that as the aircraft turned final into the wind that it would slow down and I would have the required separation to the runway threshold. Shortly after switching the A300 to the tower; I noticed that the aircraft was still fast on final and that the required wake turbulence separation no longer existed. It was at this time that I heard the local controller call the flm/coordinator position and state that the A300 was going around due to an unstabilized approach. Local control then called me and coordinated a heading and altitude for the go around and I vectored the A300 back around for an ILS approach. This is an example of why a controller should never bet on the outcome of a situation. I assumed that the A300 would get the traffic to follow in sight and that the aircraft would slow down. As soon as I took the hand off from the feeder; I should have turned the aircraft out to the left in order to give the pilot time to descend and slow down; this would have also put the aircraft in a position to execute an ILS approach. By leaving the aircraft fly directly to the FAF; I quickly ran out of options.

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Original NASA ASRS Text

Title: TRACON Controller described a go around event when traffic vectored for a visual approach lost separation with preceding traffic.

Narrative: We had just switched from a north flow operation to a south flow operation due to a wind shift associated with an area of heavy precipitation southwest of the airport. Soon after the switch; I took a handoff on a heavy A300; approaching the field from the west. The A300 appeared to be navigating directly to the FAF from the feeder as visual approaches were working well. The A300 was following another heavy aircraft to Runway 17R with multiple aircraft landing the parallel runway. The A300 had a significant overtake on the aircraft that he was following so I instructed him the reduce speed at 030. Shortly after issuing the speed reduction; I issued traffic to the A300 informing him of the traffic that he was to follow. The pilot stated that he had traffic at his 12 o'clock but it was unclear whether he had the traffic to follow in sight or the aircraft on final for the parallel runway. I then asked him if he had the airport in sight as an ILS approach was not an option from his position. The A300 reported the field in sight and I gave him a 30 degree turn to final and cleared the aircraft for the visual approach to Runway 17R. At this point the A300 was more than 4 miles in trail of the heavy aircraft that he was following and I assumed that as the aircraft turned final into the wind that it would slow down and I would have the required separation to the runway threshold. Shortly after switching the A300 to the Tower; I noticed that the aircraft was still fast on final and that the required wake turbulence separation no longer existed. It was at this time that I heard the Local Controller call the FLM/coordinator position and state that the A300 was going around due to an unstabilized approach. Local Control then called me and coordinated a heading and altitude for the go around and I vectored the A300 back around for an ILS approach. This is an example of why a Controller should never bet on the outcome of a situation. I assumed that the A300 would get the traffic to follow in sight and that the aircraft would slow down. As soon as I took the hand off from the feeder; I should have turned the aircraft out to the left in order to give the pilot time to descend and slow down; this would have also put the aircraft in a position to execute an ILS approach. By leaving the aircraft fly directly to the FAF; I quickly ran out of options.

Data retrieved from NASA's ASRS site as of July 2013 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.