Narrative:

I was working ar-O. The operation was advertising triple visual approaches 26R; 27L; 28. All three runways were in use. I needed to get below 6;000 ft to get visual approaches. In this operation; the downwind traffic from the dalas feed stays in the downwind to 26R; the logen feed to 27L; and the two south fixes to 28. The tmc was flowing occasional logens to 26R. That started this event. I was the high side; joining the final at 7;000 ft; the low side is the south side; joining at 3;500 ft; and the north side at 5;000 ft; but base aircraft come to him descending to 6;000 ft. Air carrier Y was a flowed logen to 26R. In front of him was air carrier X who I was working. For traffic; he was slowed before I turned him inbound. I turned in at 7;000 ft at 180 KTS. I saw air carrier Y coming in the base; and my plan was to stay high and wait for the north side to get the visual before descending. I advised the pilot of this. I told ar-V I was going to stay high and wait for air carrier Y to get down before I started out of 7;000 ft; because I wasn't seeing the airport until out of about 6;000 ft. Ar-V tightened air carrier Y up for 26R; and the aircraft was still fast. About 2 sweeps later I saw air carrier Y wasn't descending; and I was a little more forceful about telling ar-V to get down. He said 'oops; sorry'; and said something to air carrier Y as I was calling traffic to air carrier X. Captain activated when we were about 2.5 miles and 600 ft. I could not get air carrier X to see air carrier Y. As soon as air carrier Y was on the visual; I descended and got the visual approach to 27L. I kept air carrier X on the localizer at 7;000 ft for a few reasons. First; I heard ar-V turn in to join the 26R localizer; and I knew his visual approach was imminent. Second; the wind was from the south southwest; and if I turned to the left; I bring the low side in to play; because any arrival off my scope I couldn't see could have been descending but not well enough with a 'push' and I couldn't ensure it wouldn't create a worse scenario. Finally; it was not only safer to stay on the localizer already above the traffic; even though not legally separated; but it also ensured the user landed the first time without having overtime issue 'immediate' jarring turns. If there is a 'safe error' scenario; this is it. The other controller involved spoke to me later; and said he never heard me say anything to him initially. I thought he was looking at me as I was talking to him. He said he wasn't descending quickly because he had instructed him to slow. He didn't notice his altitude until the second time I said something. Given the same scenario; I probably would've been more forceful in telling ar-V sooner about what was unfolding. I think he just overlooked the scenario; or didn't think it was going to be an issue. I was in my airspace doing what I was supposed to be doing; but I could have done a little more looking at it now.

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Original NASA ASRS Text

Title: A80 Controller described a loss of separation event during 'triple visual approach' procedures to the west runway complex; the reporter detailing lead up factors that resulted ion the error.

Narrative: I was working AR-O. The operation was advertising triple visual approaches 26R; 27L; 28. All three runways were in use. I needed to get below 6;000 FT to get visual approaches. In this operation; the downwind traffic from the DALAS feed stays in the downwind to 26R; the LOGEN feed to 27L; and the two south fixes to 28. The TMC was flowing occasional LOGENs to 26R. That started this event. I was the high side; joining the final at 7;000 FT; the low side is the south side; joining at 3;500 FT; and the north side at 5;000 FT; but base aircraft come to him descending to 6;000 FT. Air Carrier Y was a flowed LOGEN to 26R. In front of him was Air Carrier X who I was working. For traffic; he was slowed before I turned him inbound. I turned in at 7;000 FT at 180 KTS. I saw Air Carrier Y coming in the base; and my plan was to stay high and wait for the north side to get the visual before descending. I advised the pilot of this. I told AR-V I was going to stay high and wait for Air Carrier Y to get down before I started out of 7;000 FT; because I wasn't seeing the airport until out of about 6;000 FT. AR-V tightened Air Carrier Y up for 26R; and the aircraft was still fast. About 2 sweeps later I saw Air Carrier Y wasn't descending; and I was a little more forceful about telling AR-V to get down. He said 'oops; sorry'; and said something to Air Carrier Y as I was calling traffic to Air Carrier X. Captain activated when we were about 2.5 miles and 600 FT. I could not get Air Carrier X to see Air Carrier Y. As soon as Air Carrier Y was on the visual; I descended and got the visual approach to 27L. I kept Air Carrier X on the LOC at 7;000 FT for a few reasons. First; I heard AR-V turn in to join the 26R LOC; and I knew his visual approach was imminent. Second; the wind was from the south southwest; and if I turned to the left; I bring the low side in to play; because any arrival off my scope I couldn't see could have been descending but not well enough with a 'push' and I couldn't ensure it wouldn't create a worse scenario. Finally; it was not only safer to stay on the LOC already above the traffic; even though not legally separated; but it also ensured the user landed the first time without having overtime issue 'immediate' jarring turns. If there is a 'safe error' scenario; this is it. The other controller involved spoke to me later; and said he never heard me say anything to him initially. I thought he was looking at me as I was talking to him. He said he wasn't descending quickly because he had instructed him to slow. He didn't notice his altitude until the second time I said something. Given the same scenario; I probably would've been more forceful in telling AR-V sooner about what was unfolding. I think he just overlooked the scenario; or didn't think it was going to be an issue. I was in my airspace doing what I was supposed to be doing; but I could have done a little more looking at it now.

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.