Narrative:

I was working the dal arrival position (AR7). The aircraft involved were being vectored to the parallel runways 13L & 13R for visual approaches. An E145 was arriving from the west on a procedure that is part of the problem that contributed to this event. The procedure drops the aircraft from west of the airport out of 11;000 ft; making it very difficult to get the aircraft lower and sequenced with traffic from the east side of the airport. The procedure had been suspended just prior to the event due to weather impact. The E145 was one of the first couple aircraft to come in this way again. A SR22 was inbound from the north of dal. The aircraft was following a P3; which involved wake turbulence. The P3 was following a prior ILS practice approach aircraft. I was vectoring the E145 (runway 13R) and the SR22 (runway 13L) for visual approaches into dal. I was setting up a 30 degree turn-on between the two aircraft using altitude. The SR22 did not descend as I intended. The incident occurred during the turn to final. I attempted to provide visual separation; but it was too late. The final into dal has only about 10 miles of airspace to work with. In this situation; the slow descent by the SR22 was a problem. Recommendation; to prevent the re-occurrence of this event; I would recommend cancelling what is called the 'over the top' procedure into dal. It is dangerous; fails too many times; and the complexity it causes is tremendous. This has been reported as an issue for years at this facility.

Google
 

Original NASA ASRS Text

Title: D10 Controller described a loss of separation event while sequencing traffic for DAL; noting the descent rate of one of the aircraft was slower than expected; adding the 'Over The Top' procedure was part of the problem as well.

Narrative: I was working the DAL arrival position (AR7). The aircraft involved were being vectored to the parallel Runways 13L & 13R for visual approaches. An E145 was arriving from the west on a procedure that is part of the problem that contributed to this event. The procedure drops the aircraft from west of the airport out of 11;000 FT; making it very difficult to get the aircraft lower and sequenced with traffic from the east side of the airport. The procedure had been suspended just prior to the event due to weather impact. The E145 was one of the first couple aircraft to come in this way again. A SR22 was inbound from the north of DAL. The aircraft was following a P3; which involved wake turbulence. The P3 was following a prior ILS practice approach aircraft. I was vectoring the E145 (Runway 13R) and the SR22 (Runway 13L) for visual approaches into DAL. I was setting up a 30 degree turn-on between the two aircraft using altitude. The SR22 did not descend as I intended. The incident occurred during the turn to final. I attempted to provide visual separation; but it was too late. The final into DAL has only about 10 miles of airspace to work with. In this situation; the slow descent by the SR22 was a problem. Recommendation; to prevent the re-occurrence of this event; I would recommend cancelling what is called the 'OVER THE TOP' procedure into DAL. It is dangerous; fails too many times; and the complexity it causes is tremendous. This has been reported as an issue for years at this facility.

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.