Date: 201204
Local time of day: 1801-2400
Location: ATL.Airport, US
Aircraft: Regional Jet 900 (CRJ900)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Cruise
Airspace: Class B ATL
ATC / advisory: TRACON A80
Second aircraft: Regional Jet 900 (CRJ900)
Reporter organization: Government
Reporter function: Approach; Departure
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Communication Breakdown; Situational Awareness
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Automation Air Traffic Control
Result: Air Traffic Control Issued New Clearance
Contributing factors: Procedure; Human Factors
Primary problem: Human Factors

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.




Synopsis: 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.