Narrative:

Aircraft #1, northbound level FL310. Aircraft #2 at FL350 issued descent to FL280. 3 mins later, conflict alert activated and aircraft ended up with the above separation (3 1/2 NM horizontal/900 ft vertical). (Conflict alert activated 33 seconds before loss of separation.) supplemental information from acn 406274: after reviewing my trainee with his d-side functions, I sat back down in my chair. Conflict alert activated and the radar controller who was also being trained took action. Supplemental information from acn 406336: #1 aircraft was descended to FL280 from FL350 with northbound traffic at FL310. I determined the #1 aircraft was clearly ahead of #2 aircraft. Either the computer generated data on aircraft #2 was incorrect, or the aircraft deviated to view yosemite national park. Conflict alert activated 17 seconds prior to loss of separation. Supplemental information from acn 406705: I was training a controller certified on one other radar position. We had just finished sequencing a line of aircraft to sfo. Aircraft #1 was the first aircraft in the next string. We were discussing the situation that was just finishing up, and planning for the next sequence. The trainee descended aircraft #1, thinking there was sufficient separation.

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Original NASA ASRS Text

Title: ARTCC ASSOCIATE DEVELOPMENTAL CTLR, WITH INSTRUCTOR, AND RADAR CTLR DEVELOPMENTAL, WITH INSTRUCTOR, APPARENTLY NOT AWARE THAT LOSS OF SEPARATION IS TAKING PLACE AT THE RADAR CTL POS. DSNDING ARR ACR CONFLICTS WITH XING ENRTE ACR.

Narrative: ACFT #1, NBOUND LEVEL FL310. ACFT #2 AT FL350 ISSUED DSCNT TO FL280. 3 MINS LATER, CONFLICT ALERT ACTIVATED AND ACFT ENDED UP WITH THE ABOVE SEPARATION (3 1/2 NM HORIZ/900 FT VERT). (CONFLICT ALERT ACTIVATED 33 SECONDS BEFORE LOSS OF SEPARATION.) SUPPLEMENTAL INFO FROM ACN 406274: AFTER REVIEWING MY TRAINEE WITH HIS D-SIDE FUNCTIONS, I SAT BACK DOWN IN MY CHAIR. CONFLICT ALERT ACTIVATED AND THE RADAR CTLR WHO WAS ALSO BEING TRAINED TOOK ACTION. SUPPLEMENTAL INFO FROM ACN 406336: #1 ACFT WAS DSNDED TO FL280 FROM FL350 WITH NBOUND TFC AT FL310. I DETERMINED THE #1 ACFT WAS CLRLY AHEAD OF #2 ACFT. EITHER THE COMPUTER GENERATED DATA ON ACFT #2 WAS INCORRECT, OR THE ACFT DEVIATED TO VIEW YOSEMITE NATIONAL PARK. CONFLICT ALERT ACTIVATED 17 SECONDS PRIOR TO LOSS OF SEPARATION. SUPPLEMENTAL INFO FROM ACN 406705: I WAS TRAINING A CTLR CERTIFIED ON ONE OTHER RADAR POS. WE HAD JUST FINISHED SEQUENCING A LINE OF ACFT TO SFO. ACFT #1 WAS THE FIRST ACFT IN THE NEXT STRING. WE WERE DISCUSSING THE SIT THAT WAS JUST FINISHING UP, AND PLANNING FOR THE NEXT SEQUENCE. THE TRAINEE DSNDED ACFT #1, THINKING THERE WAS SUFFICIENT SEPARATION.

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.