Narrative:

I had an large transport inbound to sfo on the runway 28 profile descent when I noticed light transport traffic just east of the large transport. I amended the large transport's altitude to remain above the light transport, he never acknowledged and I went on to other duties. The conflict alert went off a couple of mins later which brought my attention back to the situation and my attempt to stop the large transport above the light transport failed resulting in 2.9 NM and 600' sep. I should have recognized the light transport traffic before clearing the large transport on the runway 28 profile descent.

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Original NASA ASRS Text

Title: CTLR CLEARED THE LGT TO DESCEND WHICH RESULTED IN LESS THAN STANDARD SEPARATION WITH AN ACFT BELOW THE LGT.

Narrative: I HAD AN LGT INBND TO SFO ON THE RWY 28 PROFILE DSNT WHEN I NOTICED LTT TFC JUST E OF THE LGT. I AMENDED THE LGT'S ALT TO REMAIN ABOVE THE LTT, HE NEVER ACKNOWLEDGED AND I WENT ON TO OTHER DUTIES. THE CONFLICT ALERT WENT OFF A COUPLE OF MINS LATER WHICH BROUGHT MY ATTN BACK TO THE SITUATION AND MY ATTEMPT TO STOP THE LGT ABOVE THE LTT FAILED RESULTING IN 2.9 NM AND 600' SEP. I SHOULD HAVE RECOGNIZED THE LTT TFC BEFORE CLRING THE LGT ON THE RWY 28 PROFILE DSNT.

Data retrieved from NASA's ASRS site as of July 2007 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.