Narrative:

The sector radar controller accepted the handoff on air carrier X and received control from ZDV for turns and descent. Air carrier Y was eastbound at FL330 and was handed off to ZDV. Air carrier Y was shipped over to the ZDV controller. Prior to the boundary air carrier Y data block was dropped from the radar scope. Air carrier X was at FL350 and was a traffic conflict with another aircraft also at FL350. At the time there were approximately 18 aircraft in the sector. Numerous other things were going on at the same time. Air carrier X was descending to FL310 at this time. Air carrier Y was in ZDV airspace. They called back and gave control of air carrier X reference air carrier Y. The data controller received this information but did not communicate it with the radar controller. 40 seconds later air carrier X descended out of FL350. The C/a activated. Air carrier X was turned 65 degrees right and climbed to FL350. Closest proximity with air carrier Y was 4.6 mi. I believe that factors that enhanced this occurrence were poor communications between the radar and data controller. Also the radar controller dropping the data block of air carrier Y early. Callback conversation with reporter revealed the following: reporter stated experience: 3 yrs radar, 4 yrs non radar, 6 yrs military, and that this was only the second time the data controller had been on the data position. The reporter further stated that C/a activated which caused him to take action. He had dropped the data tag. We discussed the out of sight, out of mind concept, and that the data tag should be left on the radar scope until conflicting traffic is no longer a factor. Reporter admitted he forgot about air carrier Y which he had just handed off to the ZDV radar controller. System error filed. Supplemental information from acn 169315: R5 cleared air carrier Y up to FL330. ZDV advised D5, 'air carrier X your control' (told right man). Air carrier X reported on frequency at FL350. R5 dropped data block on air carrier Y. R5 cleared air carrier X to FL310. ZDV advised D5 that 'air carrier X your control for turns and lower reference air carrier Y' (did not tell right man because he was busy and he already knew air carrier X was his control). R5 instructed air carrier X to turn right to 350 degrees immediately. Air carrier X altitude FL340 and started right turn. R5 instructed air carrier X to climb to FL350. The closest proximity of air carrier X and air carrier Y was 4.5 mi and 1300' diverging. R5 dropping the data block on air carrier X and D5 not telling R5 ZDV's call 'air carrier Y your control reference air carrier X' were contributing factors in this error. Supplemental information from acn 169313: air carrier Y den-pdx. After just leveling off at FL350 with approximately 2400 hours of the flight still ahead of us, ATC directed us to descend to FL310. I conveyed my preference for an off course vector, but was again directed to descend to FL310. We established a 2000 FPM descent. When passing FL325 we were directed to climb to FL350 and make an immediate right turn of approximately 45 degrees. The descent was arrested and the climb started during the turn at FL312. At that point the TCAS ii system issued a 'traffic, traffic' advisory with the parameters as stated above. Supplemental information from acn 168825: air carrier X began a descent on our pms (performance management system) of 100 FPM. (If the controller had asked us to hurry, we would have started a manual descent as the pms is a bit slow in initiating dscnts.) we observed the converging traffic on our TCAS ii. We were passing through 32500' when the controller told us to turn to a 330 degrees heading 'immediately' and climb back to FL350. We immediately rolled into maximum allowable bank toward 330 degree heading and initiated a climb back to FL350. The converging traffic appeared to pass off of our left about 4-5 mi (on TCAS ii).

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Original NASA ASRS Text

Title: ACR X HAD LESS THAN STANDARD SEPARATION FROM ACR Y. SYSTEM ERROR. ACR Y FLT CREW DELAYED DESCENT. PLT DEVIATION.

Narrative: THE SECTOR RADAR CTLR ACCEPTED THE HDOF ON ACR X AND RECEIVED CTL FROM ZDV FOR TURNS AND DSNT. ACR Y WAS EBND AT FL330 AND WAS HANDED OFF TO ZDV. ACR Y WAS SHIPPED OVER TO THE ZDV CTLR. PRIOR TO THE BOUNDARY ACR Y DATA BLOCK WAS DROPPED FROM THE RADAR SCOPE. ACR X WAS AT FL350 AND WAS A TFC CONFLICT WITH ANOTHER ACFT ALSO AT FL350. AT THE TIME THERE WERE APPROX 18 ACFT IN THE SECTOR. NUMEROUS OTHER THINGS WERE GOING ON AT THE SAME TIME. ACR X WAS DSNDING TO FL310 AT THIS TIME. ACR Y WAS IN ZDV AIRSPACE. THEY CALLED BACK AND GAVE CTL OF ACR X REF ACR Y. THE DATA CTLR RECEIVED THIS INFO BUT DID NOT COMMUNICATE IT WITH THE RADAR CTLR. 40 SECS LATER ACR X DSNDED OUT OF FL350. THE C/A ACTIVATED. ACR X WAS TURNED 65 DEGS RIGHT AND CLBED TO FL350. CLOSEST PROX WITH ACR Y WAS 4.6 MI. I BELIEVE THAT FACTORS THAT ENHANCED THIS OCCURRENCE WERE POOR COMS BTWN THE RADAR AND DATA CTLR. ALSO THE RADAR CTLR DROPPING THE DATA BLOCK OF ACR Y EARLY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR STATED EXPERIENCE: 3 YRS RADAR, 4 YRS NON RADAR, 6 YRS MIL, AND THAT THIS WAS ONLY THE SECOND TIME THE DATA CTLR HAD BEEN ON THE DATA POS. THE RPTR FURTHER STATED THAT C/A ACTIVATED WHICH CAUSED HIM TO TAKE ACTION. HE HAD DROPPED THE DATA TAG. WE DISCUSSED THE OUT OF SIGHT, OUT OF MIND CONCEPT, AND THAT THE DATA TAG SHOULD BE LEFT ON THE RADAR SCOPE UNTIL CONFLICTING TFC IS NO LONGER A FACTOR. RPTR ADMITTED HE FORGOT ABOUT ACR Y WHICH HE HAD JUST HANDED OFF TO THE ZDV RADAR CTLR. SYS ERROR FILED. SUPPLEMENTAL INFO FROM ACN 169315: R5 CLRED ACR Y UP TO FL330. ZDV ADVISED D5, 'ACR X YOUR CTL' (TOLD R MAN). ACR X RPTED ON FREQ AT FL350. R5 DROPPED DATA BLOCK ON ACR Y. R5 CLRED ACR X TO FL310. ZDV ADVISED D5 THAT 'ACR X YOUR CTL FOR TURNS AND LOWER REF ACR Y' (DID NOT TELL R MAN BECAUSE HE WAS BUSY AND HE ALREADY KNEW ACR X WAS HIS CTL). R5 INSTRUCTED ACR X TO TURN RIGHT TO 350 DEGS IMMEDIATELY. ACR X ALT FL340 AND STARTED RIGHT TURN. R5 INSTRUCTED ACR X TO CLB TO FL350. THE CLOSEST PROX OF ACR X AND ACR Y WAS 4.5 MI AND 1300' DIVERGING. R5 DROPPING THE DATA BLOCK ON ACR X AND D5 NOT TELLING R5 ZDV'S CALL 'ACR Y YOUR CTL REF ACR X' WERE CONTRIBUTING FACTORS IN THIS ERROR. SUPPLEMENTAL INFO FROM ACN 169313: ACR Y DEN-PDX. AFTER JUST LEVELING OFF AT FL350 WITH APPROX 2400 HRS OF THE FLT STILL AHEAD OF US, ATC DIRECTED US TO DSND TO FL310. I CONVEYED MY PREFERENCE FOR AN OFF COURSE VECTOR, BUT WAS AGAIN DIRECTED TO DSND TO FL310. WE ESTABLISHED A 2000 FPM DSNT. WHEN PASSING FL325 WE WERE DIRECTED TO CLB TO FL350 AND MAKE AN IMMEDIATE RIGHT TURN OF APPROX 45 DEGS. THE DSNT WAS ARRESTED AND THE CLB STARTED DURING THE TURN AT FL312. AT THAT POINT THE TCAS II SYS ISSUED A 'TFC, TFC' ADVISORY WITH THE PARAMETERS AS STATED ABOVE. SUPPLEMENTAL INFO FROM ACN 168825: ACR X BEGAN A DSNT ON OUR PMS (PERFORMANCE MGMNT SYS) OF 100 FPM. (IF THE CTLR HAD ASKED US TO HURRY, WE WOULD HAVE STARTED A MANUAL DSNT AS THE PMS IS A BIT SLOW IN INITIATING DSCNTS.) WE OBSERVED THE CONVERGING TFC ON OUR TCAS II. WE WERE PASSING THROUGH 32500' WHEN THE CTLR TOLD US TO TURN TO A 330 DEGS HDG 'IMMEDIATELY' AND CLB BACK TO FL350. WE IMMEDIATELY ROLLED INTO MAX ALLOWABLE BANK TOWARD 330 DEG HDG AND INITIATED A CLB BACK TO FL350. THE CONVERGING TFC APPEARED TO PASS OFF OF OUR LEFT ABOUT 4-5 MI (ON TCAS II).

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.