Narrative:

A cessna 206; a VFR aircraft; had been on a photo mission for much of the day; operating north and south lines through the atlanta final approach course airspace; at an altitude of 4;500 [feet]. While working the runway 28 final during full triple simultaneous arrivals; the aircraft was being worked by the runway 26R final controller; although it was traversing back and forth through all three final's airspace. At the time of the occurrence; the aircraft was northbound about to cross the runway 28 final. I had just turned the B757-200 onto the final at 5;000 and cleared it for a visual approach to runway 28. As the B757-200 turned in; I believed the C206 might be a factor; so I called the traffic to the B757-200. He reported it in sight and I instructed him to maintain visual separation; and also informed the B757-200 he could climb to 5;000 or make a left turn to pass behind the traffic. As it became apparent that the B757-200 was not going to pass as far behind the traffic as I had first projected; I also noticed that it had continued to descend to approximately 4;500 and targets were going to come close to merging. I then instructed the B757-200; with words to the effect; that I needed him to make a slight left turn so as not to alarm that traffic that was passing through the final ahead of him. He replied that he was going to climb to 5;000. As the conflict alert (ca) alarmed; I observed the B757-200 did climb to approximately 5;000 as it passed above and slightly behind the traffic; however; it was very unnerving. The cpc in communication with the C206 did not indicate the pilot of his aircraft ever said anything. First; concerning myself; I believe I may have misapplied the use of visual separation with a wake turbulence aircraft. Although I'm not sure separation was ever actually lost; it was a lot closer than I was comfortable with. I should have either kept the B757-200 1;000 feet above the C206 until the C206 had passed behind and was well clear; or I should have cancelled the B757-200's approach clearance and given it a definitive turn to the left to pass behind the traffic; possibly in conjunction with applying visual separation. At the facility level; during good weather; we accommodate a very large number of VFR aircraft on photo missions; surveys; traffic watches; etc. The controllers here bend over backwards to assist these aircraft and provide a great service doing so. Just today we had four aircraft doing these missions in different parts of the airspace; and all four were a major factor for other traffic the controllers were working. I have seen as many as 6 to 7 of these aircraft working at the same time within or around the atlanta class B airspace. We need to take a real hard look at how many and when we approve these type operations; especially when they adversely affect atlanta arrivals and departures and the controllers working them. It is questionable in my mind as to whether or not we should have allowed the C206 to be in the atlanta 'final box' at that particular altitude while arriving three runways. The 27L; or middle final controller; had to force many of his aircraft down below the ILS glide slope for that runway in order to get them underneath the C206. Additionally; both I and the 26R final controller repeatedly had to stop aircraft above the C206 until they were clear; greatly increasing our workload. All this was done while the C206 continued right along unencumbered.

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Original NASA ASRS Text

Title: A80 Controller described an unsafe condition involving a 'special mission' aircraft transitioning the finals when full triple simultaneous approach procedures were being conducted.

Narrative: A Cessna 206; a VFR aircraft; had been on a photo mission for much of the day; operating north and south lines through the Atlanta final approach course airspace; at an altitude of 4;500 [feet]. While working the Runway 28 final during full triple simultaneous arrivals; the aircraft was being worked by the Runway 26R Final Controller; although it was traversing back and forth through all three final's airspace. At the time of the occurrence; the aircraft was northbound about to cross the Runway 28 final. I had just turned the B757-200 onto the final at 5;000 and cleared it for a visual approach to Runway 28. As the B757-200 turned in; I believed the C206 might be a factor; so I called the traffic to the B757-200. He reported it in sight and I instructed him to maintain visual separation; and also informed the B757-200 he could climb to 5;000 or make a left turn to pass behind the traffic. As it became apparent that the B757-200 was not going to pass as far behind the traffic as I had first projected; I also noticed that it had continued to descend to approximately 4;500 and targets were going to come close to merging. I then instructed the B757-200; with words to the effect; that I needed him to make a slight left turn so as not to alarm that traffic that was passing through the final ahead of him. He replied that he was going to climb to 5;000. As the Conflict Alert (CA) alarmed; I observed the B757-200 did climb to approximately 5;000 as it passed above and slightly behind the traffic; however; it was very unnerving. The CPC in communication with the C206 did not indicate the pilot of his aircraft ever said anything. First; concerning myself; I believe I may have misapplied the use of visual separation with a wake turbulence aircraft. Although I'm not sure separation was ever actually lost; it was a lot closer than I was comfortable with. I should have either kept the B757-200 1;000 feet above the C206 until the C206 had passed behind and was well clear; or I should have cancelled the B757-200's approach clearance and given it a definitive turn to the left to pass behind the traffic; possibly in conjunction with applying visual separation. At the facility level; during good weather; we accommodate a very large number of VFR aircraft on photo missions; surveys; traffic watches; etc. The controllers here bend over backwards to assist these aircraft and provide a great service doing so. Just today we had four aircraft doing these missions in different parts of the airspace; and all four were a major factor for other traffic the controllers were working. I have seen as many as 6 to 7 of these aircraft working at the same time within or around the Atlanta Class B airspace. We need to take a real hard look at how many and when we approve these type operations; especially when they adversely affect Atlanta arrivals and departures and the controllers working them. It is questionable in my mind as to whether or not we should have allowed the C206 to be in the Atlanta 'final box' at that particular altitude while arriving three runways. The 27L; or Middle Final Controller; had to force many of his aircraft down below the ILS glide slope for that runway in order to get them underneath the C206. Additionally; both I and the 26R Final Controller repeatedly had to stop aircraft above the C206 until they were clear; greatly increasing our workload. All this was done while the C206 continued right along unencumbered.

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.