Narrative:

While working seavr D side position; I saw a VFR aircraft entering the sector from the north at a mode C altitude of 16;000 ft. I called the previous sector (38) to make sure the aircraft was VFR and ask if the aircraft was in communication with anyone. After being told that the previous sector was aware of the aircraft; but was not talking to it; I informed the radar team. The VFR aircraft proceeded southbound at an mode C altitude of 16;000. The sector was very busy and I was active doing D side/RA duties which required my attention away from scanning the radar scope. Air carrier X was inbound to dfw and had been stopped at FL200 for traffic. When clear of the IFR traffic; air carrier X was descended in order to comply with the STAR/PAR landing dfw. A conflict alert was activated between air carrier X and another air carrier aircraft that was on the dual arrival route (JONEZ4); the radar controller turned air carrier X away from the JONEZ4 traffic. There were two VFR targets in the vicinity of air carrier X; one at 3;500 ft and the one at 16;000. While air carrier X was descending from FL200 to 11;000 he stated the he was climbing due to a RA. Based on the falcon data; the air carrier X and the VFR aircraft came within 300 ft of each other. Recommendation; sector traffic was very high...additional in trail/traffic restrictions would have helped lessen the traffic volume. The conflict alert between two aircraft; which were procedurally separated; added to the complexity...having the conflict alert suppressed between aircraft that are procedurally separated would have helped. I do not believe any visual alert was displayed at the sector between the IFR and the VFR aircraft....if this was the case....a visual alert would have been helpful. A VFR aircraft flying at an IFR altitude also contributed to the event...see and be seen at VFR altitudes is expected...not always expected at IFR altitudes and possibly vigilance is not as high at those times.

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Original NASA ASRS Text

Title: ZFW Controller described conflict event between IFR DFW arrival and a VFR overflight; the reporter indicated the conflict alert generated by the procedurally separated traffic may have impacted the IFR/VFR traffic alert.

Narrative: While working SEAVR D side position; I saw a VFR aircraft entering the sector from the north at a Mode C altitude of 16;000 FT. I called the previous sector (38) to make sure the aircraft was VFR and ask if the aircraft was in communication with anyone. After being told that the previous sector was aware of the aircraft; but was not talking to it; I informed the RADAR team. The VFR aircraft proceeded southbound at an Mode C altitude of 16;000. The sector was very busy and I was active doing D side/RA duties which required my attention away from scanning the RADAR scope. Air Carrier X was inbound to DFW and had been stopped at FL200 for traffic. When clear of the IFR traffic; Air Carrier X was descended in order to comply with the STAR/PAR landing DFW. A conflict alert was activated between Air Carrier X and another air carrier aircraft that was on the dual arrival route (JONEZ4); the RADAR Controller turned Air Carrier X away from the JONEZ4 traffic. There were two VFR targets in the vicinity of Air Carrier X; one at 3;500 FT and the one at 16;000. While Air Carrier X was descending from FL200 to 11;000 he stated the he was climbing due to a RA. Based on the FALCON data; the Air Carrier X and the VFR aircraft came within 300 FT of each other. Recommendation; sector traffic was very high...additional in trail/traffic restrictions would have helped lessen the traffic volume. The conflict alert between two aircraft; which were procedurally separated; added to the complexity...having the conflict alert suppressed between aircraft that are procedurally separated would have helped. I do not believe any visual alert was displayed at the sector between the IFR and the VFR aircraft....if this was the case....a visual alert would have been helpful. A VFR aircraft flying at an IFR altitude also contributed to the event...see and be seen at VFR altitudes is expected...not always expected at IFR altitudes and possibly vigilance is not as high at those times.

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.