Narrative:

The final controller was given an aircraft (aircraft X) 30 miles south of slc airport; established in final at 10;000 ft (an off-load from the jordan controller). About the same time he took radar on 2 aircraft approximately 5 miles southwest of the airport; one established in the downwind at 11;000 ft (aircraft #1: bear controller); and the other turning to the downwind a mile or so in trail descending to 12;000 ft (aircraft #2: stockton controller). He estimated he could base and clear and base both aircraft #1 and aircraft #2 for visual approaches in front of aircraft #3; so he slowed aircraft #3 to 190 KTS. The controller cleared aircraft #1 for a visual and observed him leaving 10;200 ft. He instructed the aircraft #2 to slow to 190 KTS then descended it to 11;000 ft. He asked aircraft #1 to report base turn; in order to expedite the descent of aircraft #2. When aircraft #1 reported the base turn; he instructed aircraft #2 to expedite to 9;000 ft. A few seconds later; after aircraft #2 was south of aircraft #1; he based aircraft #2 by instructing it to turn left heading 070 degrees. He waited; after the aircraft failed to start the turn and seeing the situation develop because aircraft #2 was not descending as rapidly as anticipated; he instructed aircraft #2 to turn left heading 360 degrees. A conversation ensued between the pilot (aircraft #2) and the controller about that particular heading. It appeared to the controller that aircraft #2 had failed to start the turn. The controller asked the pilot what heading it was passing. The pilot replied 150 degrees. The controller instructed the pilot to amend his heading to 160 degrees. The aircraft appeared to continue the expeditious descent to 9;000 ft and turned to a heading of 160 degrees. The controller evaluated the situation and it appeared that separation of 3 miles and/or 1;000 ft prior to aircraft #2 and aircraft #3 passing. He issued traffic to aircraft #2 and aircraft #3; neither could acquire the other. He instructed aircraft #3 he would have his approach clearance as soon as he was north of aircraft #2 and 9;000 ft. The controller remembered seeing aircraft #2 at 9;100 ft at what he believed to be 3 miles apart. Once aircraft #3 was north of aircraft #2; he cleared aircraft #3 for a visual approach. Controller based aircraft #2 for the visual and then cleared it for a subsequent visual approach. The problem arose with the controller being too aggressive; basing aircraft #2 too high; and anticipating aircraft #2 would be complete a standard turn; due to VFR conditions. How was it discovered? A few hours later; after work; doubt as to whether vertical separation was attained prior to the loss of 3 miles: still to be determined if separation was lost. Corrective action: do not go into a hole/space/gap without 1;000 ft separation. Could have turned aircraft #2 to a heading 45 degrees right of the reciprocal course of aircraft #3; left aircraft #2 on the base turn and turn aircraft #3 to a 310 degree heading for re-sequence; and best: cleared aircraft #3 and kept aircraft #2 on the downwind to follow aircraft #3.

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Original NASA ASRS Text

Title: S56 Controller described proximity event when Final Controller failed to ensure final turn on to an aircraft on a visual approach resulting in a near loss of separation.

Narrative: The Final Controller was given an aircraft (Aircraft X) 30 miles south of SLC Airport; established in final at 10;000 FT (an off-load from the Jordan Controller). About the same time he took radar on 2 aircraft approximately 5 miles southwest of the airport; one established in the downwind at 11;000 FT (Aircraft #1: Bear Controller); and the other turning to the downwind a mile or so in trail descending to 12;000 FT (Aircraft #2: Stockton Controller). He estimated he could base and clear and base both Aircraft #1 and Aircraft #2 for visual approaches in front of Aircraft #3; so he slowed aircraft #3 to 190 KTS. The Controller cleared Aircraft #1 for a visual and observed him leaving 10;200 FT. He instructed the Aircraft #2 to slow to 190 KTS then descended it to 11;000 FT. He asked Aircraft #1 to report base turn; in order to expedite the descent of Aircraft #2. When Aircraft #1 reported the base turn; he instructed Aircraft #2 to expedite to 9;000 FT. A few seconds later; after Aircraft #2 was south of Aircraft #1; he based Aircraft #2 by instructing it to turn left heading 070 degrees. He waited; after the aircraft failed to start the turn and seeing the situation develop because Aircraft #2 was not descending as rapidly as anticipated; he instructed Aircraft #2 to turn left heading 360 degrees. A conversation ensued between the pilot (Aircraft #2) and the Controller about that particular heading. It appeared to the Controller that Aircraft #2 had failed to start the turn. The Controller asked the pilot what heading it was passing. The Pilot replied 150 degrees. The Controller instructed the Pilot to amend his heading to 160 degrees. The aircraft appeared to continue the expeditious descent to 9;000 FT and turned to a heading of 160 degrees. The Controller evaluated the situation and it appeared that separation of 3 miles and/or 1;000 FT prior to aircraft #2 and Aircraft #3 passing. He issued traffic to Aircraft #2 and Aircraft #3; neither could acquire the other. He instructed Aircraft #3 he would have his approach clearance as soon as he was north of Aircraft #2 and 9;000 FT. The Controller remembered seeing Aircraft #2 at 9;100 FT at what he believed to be 3 miles apart. Once Aircraft #3 was north of Aircraft #2; he cleared Aircraft #3 for a visual approach. Controller based Aircraft #2 for the visual and then cleared it for a subsequent visual approach. The problem arose with the Controller being too aggressive; basing Aircraft #2 too high; and anticipating Aircraft #2 would be complete a standard turn; due to VFR conditions. How was it discovered? A few hours later; after work; doubt as to whether vertical separation was attained prior to the loss of 3 miles: still to be determined if separation was lost. Corrective action: Do not go into a hole/space/gap without 1;000 FT separation. Could have turned Aircraft #2 to a heading 45 degrees right of the reciprocal course of Aircraft #3; left Aircraft #2 on the base turn and turn Aircraft #3 to a 310 degree heading for re-sequence; and best: cleared Aircraft #3 and kept Aircraft #2 on the downwind to follow Aircraft #3.

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.