Narrative:

The occurrence happened while I was working 3 radar sectors combined. These are lake, bear and hart. Traffic workload was light. This is typically the end of our last departure bank that happens between X15P and Y00P every evening. Small transport X was outbound to twf climbing to 16000 MSL. Air carrier Y was also departing slc and in-trail of small transport X by 4 mins, going to pdx, climbing to 16000 MSL. Our procedures call for both of these aircraft to be routed through a departure gate and handed off to salt lake center (ZLC). As per letter of agreement with ZLC, I instructed small transport X to intercept the slc VOR 296 degree radial and track nwbound, due to the fact that he was filed slc direct twf. Air carrier Y was filed slc J12 pdx. Because of a large overtake, I initiated a direct routing to pdx with air carrier Y, to keep him south of small transport X who was established on the slc VOR 296 degree radial. I attempted to contact ZLC, sector 40 and advise them of my actions. After 2 attempts, on our landline, to sector 40 I was unable to get ahold of them. At this point, I turned air carrier Y to a heading of 310 degree and advised him to resume own navigation on J12 (slc VOR 296 degree radial). Air carrier Y was approximately 10 mi behind small transport X and was climbing out of 12000 MSL when I transferred radio communication to ZLC sector 40. Air carrier Y had twice the climb rate of small transport X and I believed ZLC sector 40 would continue to climb air carrier Y. Wrong! Air carrier Y leveled at 16000 MSL for 50 seconds before ZLC sector 40 climbed him. Small transport X also was climbing to 16000 with air carrier Y on a converging course behind and to his left. When I observed air carrier Y leaving 15000 MSL, I transferred radio communication of small transport X to ZLC sector 40. Small transport X was leaving 14000 MSL. I observed the 2 aircraft getting close and notified my supervisor. The subsequent computer printout of the 2 aircraft indicated that they were 4.59 mi apart and 600 ft vertical at their closest point. ZLC needs 5 mi or 1000 ft vertical for min separation. I assumed ZLC sector 4O would continue to climb air carrier Y.

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Original NASA ASRS Text

Title: SMT X HAD LTSS FROM ACR Y. SYSTEM ERROR.

Narrative: THE OCCURRENCE HAPPENED WHILE I WAS WORKING 3 RADAR SECTORS COMBINED. THESE ARE LAKE, BEAR AND HART. TFC WORKLOAD WAS LIGHT. THIS IS TYPICALLY THE END OF OUR LAST DEP BANK THAT HAPPENS BTWN X15P AND Y00P EVERY EVENING. SMT X WAS OUTBOUND TO TWF CLBING TO 16000 MSL. ACR Y WAS ALSO DEPARTING SLC AND IN-TRAIL OF SMT X BY 4 MINS, GOING TO PDX, CLBING TO 16000 MSL. OUR PROCS CALL FOR BOTH OF THESE ACFT TO BE ROUTED THROUGH A DEP GATE AND HANDED OFF TO SALT LAKE CENTER (ZLC). AS PER LETTER OF AGREEMENT WITH ZLC, I INSTRUCTED SMT X TO INTERCEPT THE SLC VOR 296 DEG RADIAL AND TRACK NWBOUND, DUE TO THE FACT THAT HE WAS FILED SLC DIRECT TWF. ACR Y WAS FILED SLC J12 PDX. BECAUSE OF A LARGE OVERTAKE, I INITIATED A DIRECT ROUTING TO PDX WITH ACR Y, TO KEEP HIM S OF SMT X WHO WAS ESTABLISHED ON THE SLC VOR 296 DEG RADIAL. I ATTEMPTED TO CONTACT ZLC, SECTOR 40 AND ADVISE THEM OF MY ACTIONS. AFTER 2 ATTEMPTS, ON OUR LANDLINE, TO SECTOR 40 I WAS UNABLE TO GET AHOLD OF THEM. AT THIS POINT, I TURNED ACR Y TO A HDG OF 310 DEG AND ADVISED HIM TO RESUME OWN NAV ON J12 (SLC VOR 296 DEG RADIAL). ACR Y WAS APPROX 10 MI BEHIND SMT X AND WAS CLBING OUT OF 12000 MSL WHEN I TRANSFERRED RADIO COM TO ZLC SECTOR 40. ACR Y HAD TWICE THE CLB RATE OF SMT X AND I BELIEVED ZLC SECTOR 40 WOULD CONTINUE TO CLB ACR Y. WRONG! ACR Y LEVELED AT 16000 MSL FOR 50 SECONDS BEFORE ZLC SECTOR 40 CLBED HIM. SMT X ALSO WAS CLBING TO 16000 WITH ACR Y ON A CONVERGING COURSE BEHIND AND TO HIS L. WHEN I OBSERVED ACR Y LEAVING 15000 MSL, I TRANSFERRED RADIO COM OF SMT X TO ZLC SECTOR 40. SMT X WAS LEAVING 14000 MSL. I OBSERVED THE 2 ACFT GETTING CLOSE AND NOTIFIED MY SUPVR. THE SUBSEQUENT COMPUTER PRINTOUT OF THE 2 ACFT INDICATED THAT THEY WERE 4.59 MI APART AND 600 FT VERT AT THEIR CLOSEST POINT. ZLC NEEDS 5 MI OR 1000 FT VERT FOR MIN SEPARATION. I ASSUMED ZLC SECTOR 4O WOULD CONTINUE TO CLB ACR Y.

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.