Narrative:

I had been working final for about 10 minutes when the feeder stacked a B777 at 8;000 ft over the VOR for noise abatement. Instead of vectoring out an A320 from the south he stacked the A320 at 9;000 ft. This situation is unsafe due to the proximity to the final. It's to close and both aircraft have a hard time achieving a stable approach. An E120 coming in from the south was 6-7 miles south of the A320. I issued traffic to the E120 and he reported the E120 in sight. I told him to maintain visual separation and he acknowledge it. I got busy making side by's with other aircraft and didn't notice the overtake with the A320's side by aircraft. I can't remember the call sign; but issued traffic to the E120 and he said he was looking. I continued making side by's with other aircraft. I went back to the E120 and its transmission was blocked. He reported the other aircraft in sight and I told him to maintain visual separation. By that time I believe I had less than approved separation. Later [the feeder] had [the A320] coming over [another] VOR to land on runway 28L showing 325 [KTS] over the ground. I asked him his airspeed and he replied 250 KTS. It's standard to have aircraft coming over [the other] VOR at 210 KTS or less. It makes it very hard to slow them down and have them [at] a good altitude to be based and make a good side by. If aircraft over [the first] VOR at 8;000 ft for noise abatement then [next sector] shouldn't stack another aircraft at 9;000 ft. They should vector aircraft to the west and put them in trail at 6;000 ft. It helps out the finals and makes it easier for the pilot to have a stable approach on final.

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Original NASA ASRS Text

Title: TRACON Controller described a loss of required wake turbulence separation claiming the Feeder Controller failed to provide a workable feed given the final airspace constraints.

Narrative: I had been working Final for about 10 minutes when the Feeder stacked a B777 at 8;000 FT over the VOR for noise abatement. Instead of vectoring out an A320 from the south he stacked the A320 at 9;000 FT. This situation is unsafe due to the proximity to the final. It's to close and both aircraft have a hard time achieving a stable approach. An E120 coming in from the south was 6-7 miles south of the A320. I issued traffic to the E120 and he reported the E120 in sight. I told him to maintain visual separation and he acknowledge it. I got busy making side by's with other aircraft and didn't notice the overtake with the A320's side by aircraft. I can't remember the call sign; but issued traffic to the E120 and he said he was looking. I continued making side by's with other aircraft. I went back to the E120 and its transmission was blocked. He reported the other aircraft in sight and I told him to maintain visual separation. By that time I believe I had less than approved separation. Later [the Feeder] had [the A320] coming over [another] VOR to land on Runway 28L showing 325 [KTS] over the ground. I asked him his airspeed and he replied 250 KTS. It's standard to have aircraft coming over [the other] VOR at 210 KTS or less. It makes it very hard to slow them down and have them [at] a good altitude to be based and make a good side by. If aircraft over [the first] VOR at 8;000 FT for noise abatement then [next sector] shouldn't stack another aircraft at 9;000 FT. They should vector aircraft to the west and put them in trail at 6;000 FT. It helps out the finals and makes it easier for the pilot to have a stable approach on final.

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.