Narrative:

Air carrier X on the frogo departure originally cleared by sector 34 to FL270. Air carrier Y on modesto 1 arrival to sfo cleared to descend to FL280. Another air carrier was also preceding air carrier X on the frogo climbing FL270, approximately 15 mi in front and 30 KTS faster than air carrier X. Air carrier Y received amended altitude clearance to FL310. Air carrier X was cleared to FL290. This is the last point at which I was aware of speeds, which were holding steady. Air carrier X exhibited a good climb rate and was cleared to FL330, at which point air carrier X requested FL370 and received that clearance. At this point, it appeared air carrier X would pass sufficiently behind air carrier Y to maintain approved sep. I began coordination with sector 15 to vector an air carrier behind a sjc arrival and received alternate instructions from sector 15. I attempted to pass these instructions to my radar person, only to find that he had noticed the conflict between air carrier X and air carrier Y and was issuing headings to both aircraft. I was not aware of the conflict until I heard the headings issued. Conflict arose due to mistakenly predicting climb rates/speeds and allowing too much attention to be diverted to other situations. High winds also increased the speed of air carrier X, which was not expected. Conflict could be prevented by issuing clrncs more consistent with a worst case scenario, allowing other situations more attention. Supplemental information from acn 123959: I was working sector 34 at ZOA. I told my d-side to tell sector 15 I would vector my aircraft behind their el nido arrival. At this point, I noticed air carrier X was in possible conflict with air carrier Y. I noticed the airspeed increased and saw that the climb rate was not sufficient enough to climb above air carrier Y. I turned air carrier X to the left to avoid a system error and turned the air carrier Y to the left.

Related reports:

Google
 

Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION BETWEEN ACR X AND Y.

Narrative: ACR X ON THE FROGO DEP ORIGINALLY CLRED BY SECTOR 34 TO FL270. ACR Y ON MODESTO 1 ARR TO SFO CLRED TO DSND TO FL280. ANOTHER ACR WAS ALSO PRECEDING ACR X ON THE FROGO CLBING FL270, APPROX 15 MI IN FRONT AND 30 KTS FASTER THAN ACR X. ACR Y RECEIVED AMENDED ALT CLRNC TO FL310. ACR X WAS CLRED TO FL290. THIS IS THE LAST POINT AT WHICH I WAS AWARE OF SPDS, WHICH WERE HOLDING STEADY. ACR X EXHIBITED A GOOD CLB RATE AND WAS CLRED TO FL330, AT WHICH POINT ACR X REQUESTED FL370 AND RECEIVED THAT CLRNC. AT THIS POINT, IT APPEARED ACR X WOULD PASS SUFFICIENTLY BEHIND ACR Y TO MAINTAIN APPROVED SEP. I BEGAN COORD WITH SECTOR 15 TO VECTOR AN ACR BEHIND A SJC ARR AND RECEIVED ALTERNATE INSTRUCTIONS FROM SECTOR 15. I ATTEMPTED TO PASS THESE INSTRUCTIONS TO MY RADAR PERSON, ONLY TO FIND THAT HE HAD NOTICED THE CONFLICT BTWN ACR X AND ACR Y AND WAS ISSUING HDGS TO BOTH ACFT. I WAS NOT AWARE OF THE CONFLICT UNTIL I HEARD THE HDGS ISSUED. CONFLICT AROSE DUE TO MISTAKENLY PREDICTING CLB RATES/SPDS AND ALLOWING TOO MUCH ATTN TO BE DIVERTED TO OTHER SITUATIONS. HIGH WINDS ALSO INCREASED THE SPD OF ACR X, WHICH WAS NOT EXPECTED. CONFLICT COULD BE PREVENTED BY ISSUING CLRNCS MORE CONSISTENT WITH A WORST CASE SCENARIO, ALLOWING OTHER SITUATIONS MORE ATTN. SUPPLEMENTAL INFO FROM ACN 123959: I WAS WORKING SECTOR 34 AT ZOA. I TOLD MY D-SIDE TO TELL SECTOR 15 I WOULD VECTOR MY ACFT BEHIND THEIR EL NIDO ARR. AT THIS POINT, I NOTICED ACR X WAS IN POSSIBLE CONFLICT WITH ACR Y. I NOTICED THE AIRSPD INCREASED AND SAW THAT THE CLB RATE WAS NOT SUFFICIENT ENOUGH TO CLB ABOVE ACR Y. I TURNED ACR X TO THE LEFT TO AVOID A SYS ERROR AND TURNED THE ACR Y TO THE LEFT.

Data retrieved from NASA's ASRS site as of August 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.