Narrative:

Air carrier X, an medium large transport, was descending to FL210, 10 NM northwest of fim VOR, landing at lax. Air carrier Y, an medium large transport, was descending to FL220, 20 NM east of fim VOR, landing at small aircraft. The descent clearance was given to air carrier Y to descend from FL240 to FL200 in sufficient time to allow the aircraft to arrive at FL200 before air carrier X arrived at FL210, or before either aircraft come closer than 5 NM from each other. The controller's attention was distraction from this situation by 2 other aircraft about 80 NM west of fim VOR. By the time the controller had insured that the 2 aircraft 80 NM west of fim VOR are separated, air carrier X and air carrier Y were observed to be in conflict. Both aircraft were vectored, and air carrier Y was instructed to expedite descent. The aircraft passed within 2.5 NM horizontal, and 600' vertical at the closest point. The radar controller was working 2 radar sectors combined at one position, traffic was moderate (10 aircraft) and moderately complex. The radar associate position was manned at the time. The error was a direct result of the right controller's being distraction by another situation, by not having timely communications transferred of air carrier Y to begin descent, and of 2 sectors being combined when traffic justified their being not combined.

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Original NASA ASRS Text

Title: ACR WAS ISSUED A DESCENT THROUGH AN ALT OCCUPIED BY ANOTHER ACR RESULTING IN LESS THAN STANDARD SEPARATION.

Narrative: ACR X, AN MLG, WAS DSNDING TO FL210, 10 NM NW OF FIM VOR, LNDG AT LAX. ACR Y, AN MLG, WAS DSNDING TO FL220, 20 NM E OF FIM VOR, LNDG AT SMA. THE DSNT CLRNC WAS GIVEN TO ACR Y TO DSND FROM FL240 TO FL200 IN SUFFICIENT TIME TO ALLOW THE ACFT TO ARRIVE AT FL200 BEFORE ACR X ARRIVED AT FL210, OR BEFORE EITHER ACFT COME CLOSER THAN 5 NM FROM EACH OTHER. THE CTLR'S ATTN WAS DISTR FROM THIS SITUATION BY 2 OTHER ACFT ABOUT 80 NM W OF FIM VOR. BY THE TIME THE CTLR HAD INSURED THAT THE 2 ACFT 80 NM W OF FIM VOR ARE SEPARATED, ACR X AND ACR Y WERE OBSERVED TO BE IN CONFLICT. BOTH ACFT WERE VECTORED, AND ACR Y WAS INSTRUCTED TO EXPEDITE DSNT. THE ACFT PASSED WITHIN 2.5 NM HORIZ, AND 600' VERT AT THE CLOSEST POINT. THE RADAR CTLR WAS WORKING 2 RADAR SECTORS COMBINED AT ONE POS, TFC WAS MODERATE (10 ACFT) AND MODERATELY COMPLEX. THE RADAR ASSOCIATE POS WAS MANNED AT THE TIME. THE ERROR WAS A DIRECT RESULT OF THE R CTLR'S BEING DISTR BY ANOTHER SITUATION, BY NOT HAVING TIMELY COMS TRANSFERRED OF ACR Y TO BEGIN DSNT, AND OF 2 SECTORS BEING COMBINED WHEN TFC JUSTIFIED THEIR BEING NOT COMBINED.

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.