Narrative:

I had a situation yesterday morning while working final; and I'm not absolutely certain that I had separation. There were scattered clouds in the area that were limiting visual approaches from the west or straight-in to runway 17R; but I was able to obtain visual approaches from the east for runway 17L. Several aircraft asked for lower in order to obtain the visual approach; and I continued to do this based on these first few aircraft seeing the airport as they descended beneath the scattered layer. As I descended the runway 17L aircraft to 2;100; I staggered the others to runway 17R in anticipation of an ILS if one or the other did not report the airport in sight. This was working well until the last pair of aircraft (a MD80 and a small GA aircraft). The MD80 was originally sequenced to runway 17L by the re controller because this runway is closest to the MD80's gate. I changed the MD80 to runway 17R for airport balance and to stagger if necessary. I thought that the GA had been descended to 2;100 and cleared for the visual approach to runway 17L. The MD80 was on a left base for runway 17R; but still at 3;500. As I turned and descended the MD80; it suddenly clicked that I was maintaining a stagger altitude in anticipation of the visual approach; but that neither aircraft had actually been cleared for the visual approach. I went back to the GA and asked if he had the airport in sight; because the MD80 did not; he said that he was just breaking out of the clouds. The GA reported the airport in sight; and I cleared him for the visual approach. The MD80 was then cleared for the approach; but I don't recall if it was an ILS or visual approach. Radar west and radar east were open; there was a flm in the TRACON; and the tower was fully staffed. No one indicated any concern at the time; and no one questioned the separation or spacing as the operation as it was developing. No one suggested or directed me to break-out the MD80 or the GA. It was brought to my attention this morning by another controller; that I may have had an error with these two aircraft. In retrospect; I don't think that I had the required separation at the time when the MD80 was issued a visual approach clearance. I have no idea why I did not initiate or clear the GA for a visual approach earlier. Recommendation; since the MD80 was to be initially staggered behind a slower GA aircraft; I should have provided myself with some additional spacing in case visual approaches quit working. I should have solicited and cleared the GA for a visual approach as I had done with all of the other runway 17L aircraft.

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Original NASA ASRS Text

Title: TRACON Controller described a possible loss of separation event when attempting to conduct Visual Approaches in questionable weather conditions.

Narrative: I had a situation yesterday morning while working Final; and I'm not absolutely certain that I had separation. There were scattered clouds in the area that were limiting Visual Approaches from the west or straight-in to Runway 17R; but I was able to obtain Visual Approaches from the east for Runway 17L. Several aircraft asked for lower in order to obtain the Visual Approach; and I continued to do this based on these first few aircraft seeing the airport as they descended beneath the scattered layer. As I descended the Runway 17L aircraft to 2;100; I staggered the others to Runway 17R in anticipation of an ILS if one or the other did not report the airport in sight. This was working well until the last pair of aircraft (a MD80 and a small GA aircraft). The MD80 was originally sequenced to Runway 17L by the RE Controller because this runway is closest to the MD80's gate. I changed the MD80 to Runway 17R for airport balance and to stagger if necessary. I thought that the GA had been descended to 2;100 and cleared for the Visual Approach to Runway 17L. The MD80 was on a left base for Runway 17R; but still at 3;500. As I turned and descended the MD80; it suddenly clicked that I was maintaining a stagger altitude in anticipation of the Visual Approach; but that neither aircraft had actually been cleared for the Visual Approach. I went back to the GA and asked if he had the airport in sight; because the MD80 did not; he said that he was just breaking out of the clouds. The GA reported the airport in sight; and I cleared him for the Visual Approach. The MD80 was then cleared for the approach; but I don't recall if it was an ILS or Visual Approach. Radar West and Radar East were open; there was a FLM in the TRACON; and the Tower was fully staffed. No one indicated any concern at the time; and no one questioned the separation or spacing as the operation as it was developing. No one suggested or directed me to break-out the MD80 or the GA. It was brought to my attention this morning by another Controller; that I may have had an error with these two aircraft. In retrospect; I don't think that I had the required separation at the time when the MD80 was issued a Visual Approach clearance. I have no idea why I did not initiate or clear the GA for a Visual Approach earlier. Recommendation; since the MD80 was to be initially staggered behind a slower GA aircraft; I should have provided myself with some additional spacing in case Visual Approaches quit working. I should have solicited and cleared the GA for a Visual Approach as I had done with all of the other Runway 17L 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.