Narrative:

Aircraft Y was orbiting VFR in an area 5 NM northeast of opf airport at 2;500 ft MSL in class east airspace (above class D but below the class B with no clearance to enter class B). Aircraft X inbound IFR to opf from the east was on a west vector at 3;000 ft MSL about 4 nm north of opf to set up for the left downwind runway 12 at opf. As aircraft X (officially in class B airspace at this time) approached the area that aircraft Y was maneuvering; traffic was exchanged with both aircraft; who both said they would be looking; and normal class C IFR/VFR separation was going to be preserved with 500 ft vertical between the two aircraft. As aircraft X was directly overhead aircraft Y; he declared a TCAS RA and climbed about 200-300 ft I acknowledged with a 'roger' and told him that the C206 was still 500 ft below him. No other conversation took place regarding the RA and I descended aircraft X to 2;000 ft MSL after passing aircraft Y and cleared aircraft X for the approach into opf with no further incident. Recommendation; this seems like an open-and-shut case of regular TCAS RA issues. Maybe the GLF3's TCAS was more sensitive than other aircraft that were maneuvering near the VFR C206; because no one else complained about the proximity of the C206. A 500 ft separation criteria should maybe be incorporated into standard IFR aircraft TCAS equipment as a normal vertical separation with VFR aircraft. This is not the first time that an IFR aircraft has complained in reference to TCAS and being 500 ft above/below a VFR target. Maybe it is a persistent problem with aircraft all over the country when 500 ft vertical separation is applied with IFR to VFR aircraft.

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Original NASA ASRS Text

Title: MIA Controller described a TCAS RA event between an IFR arrival to OPF and a VFR maneuvering aircraft with the required 500 FT separation provided.

Narrative: Aircraft Y was orbiting VFR in an area 5 NM northeast of OPF Airport at 2;500 FT MSL in Class E airspace (above Class D but below the Class B with no clearance to enter Class B). Aircraft X inbound IFR to OPF from the East was on a West vector at 3;000 FT MSL about 4 nm North of OPF to set up for the left downwind Runway 12 at OPF. As Aircraft X (officially in Class B airspace at this time) approached the area that Aircraft Y was maneuvering; traffic was exchanged with both aircraft; who both said they would be looking; and normal Class C IFR/VFR separation was going to be preserved with 500 FT vertical between the two aircraft. As Aircraft X was directly overhead Aircraft Y; he declared a TCAS RA and climbed about 200-300 FT I acknowledged with a 'roger' and told him that the C206 was still 500 FT below him. No other conversation took place regarding the RA and I descended Aircraft X to 2;000 FT MSL after passing Aircraft Y and cleared Aircraft X for the approach into OPF with no further incident. Recommendation; this seems like an open-and-shut case of regular TCAS RA issues. Maybe the GLF3's TCAS was more sensitive than other aircraft that were maneuvering near the VFR C206; because no one else complained about the proximity of the C206. A 500 FT separation criteria should maybe be incorporated into standard IFR aircraft TCAS equipment as a normal vertical separation with VFR aircraft. This is not the first time that an IFR aircraft has complained in reference to TCAS and being 500 FT above/below a VFR target. Maybe it is a persistent problem with aircraft all over the country when 500 FT vertical separation is applied with IFR to VFR aircraft.

Data retrieved from NASA's ASRS site as of April 2012 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.