Narrative:

Aircraft #1 was inbound to psc at FL310. Traffic in the sectors (47 and 48 combined) was moderate to busy. There was traffic for aircraft #1 in descent, aircraft #3 at FL290, opposite direction, and aircraft #2 eastbound out of pdx on J16. The aircraft were still quite far apart and aircraft #1 was issued a pilot's discretion descent to FL240. I think I gave more attention to the opposite direction traffic and missed aircraft #2 as he converged with aircraft #1. There were numerous data blocks in a small area when the conflict alert activated. I immediately issued FL310 back to aircraft #1 and issued FL280 to aircraft #2. Aircraft #2 said he was out of FL290 and had an RA. Closest proximity was 1700 ft and 3.2 NM. There was a developmental certified on the position working my d-side who also failed to recognize the traffic. Sector 47 and sector 48 are seldom decombined due to a poor design. I think the error was simply a failure to re-evaluate aircraft #2 as traffic on my ensuing scans. Supplemental information from acn 620131: after evaluating the situation, my r-side issued a pilot's discretion descent. However, due to the nature of a pilot's discretion descent clearance, aircraft #2 was still traffic vertically. I was performing my functions, coordinating as necessary, and discussing traffic sits with my r-side. We both missed the more immediate traffic. Supplemental information from acn 620127: the radar controller, for whatever reason, didn't recognize aircraft #2 as traffic for aircraft #1. 15 controllers assigned to the shift. 9 controllers on position, 1 developmental training. 4 cpc's on break. 1 cpc in training. 2 oj's on duty -- 1 on position in area, 1 in training.

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Original NASA ASRS Text

Title: ZSE CTLR EXPERIENCED OPERROR BTWN FL290 AND FL310 WITH XING AND DSNDING TFC.

Narrative: ACFT #1 WAS INBOUND TO PSC AT FL310. TFC IN THE SECTORS (47 AND 48 COMBINED) WAS MODERATE TO BUSY. THERE WAS TFC FOR ACFT #1 IN DSCNT, ACFT #3 AT FL290, OPPOSITE DIRECTION, AND ACFT #2 EBOUND OUT OF PDX ON J16. THE ACFT WERE STILL QUITE FAR APART AND ACFT #1 WAS ISSUED A PLT'S DISCRETION DSCNT TO FL240. I THINK I GAVE MORE ATTN TO THE OPPOSITE DIRECTION TFC AND MISSED ACFT #2 AS HE CONVERGED WITH ACFT #1. THERE WERE NUMEROUS DATA BLOCKS IN A SMALL AREA WHEN THE CONFLICT ALERT ACTIVATED. I IMMEDIATELY ISSUED FL310 BACK TO ACFT #1 AND ISSUED FL280 TO ACFT #2. ACFT #2 SAID HE WAS OUT OF FL290 AND HAD AN RA. CLOSEST PROX WAS 1700 FT AND 3.2 NM. THERE WAS A DEVELOPMENTAL CERTIFIED ON THE POS WORKING MY D-SIDE WHO ALSO FAILED TO RECOGNIZE THE TFC. SECTOR 47 AND SECTOR 48 ARE SELDOM DECOMBINED DUE TO A POOR DESIGN. I THINK THE ERROR WAS SIMPLY A FAILURE TO RE-EVALUATE ACFT #2 AS TFC ON MY ENSUING SCANS. SUPPLEMENTAL INFO FROM ACN 620131: AFTER EVALUATING THE SIT, MY R-SIDE ISSUED A PLT'S DISCRETION DSCNT. HOWEVER, DUE TO THE NATURE OF A PLT'S DISCRETION DSCNT CLRNC, ACFT #2 WAS STILL TFC VERTLY. I WAS PERFORMING MY FUNCTIONS, COORDINATING AS NECESSARY, AND DISCUSSING TFC SITS WITH MY R-SIDE. WE BOTH MISSED THE MORE IMMEDIATE TFC. SUPPLEMENTAL INFO FROM ACN 620127: THE RADAR CTLR, FOR WHATEVER REASON, DIDN'T RECOGNIZE ACFT #2 AS TFC FOR ACFT #1. 15 CTLRS ASSIGNED TO THE SHIFT. 9 CTLRS ON POS, 1 DEVELOPMENTAL TRAINING. 4 CPC'S ON BREAK. 1 CPC IN TRAINING. 2 OJ'S ON DUTY -- 1 ON POS IN AREA, 1 IN TRAINING.

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.