Narrative:

Small transport X was level at FL230. Air carrier Y was level at FL220. Small transport X destination was 78D. I received permission from ZAU to descend small transport X, who was eastbound, with respect to air carrier Y, who was westbound. I informed the radar controller that small transport X was his control for descent. I did not mention air carrier Y because the aircraft was on the scope in our sector. I answered several calls from ZAU and did not hear the radar controller issue a lower altitude to small transport X. When I realized that small transport X was descending head on at air carrier Y, the radar controller had already taken corrective action. A major factor was an aircraft level at FL210 southbound. The radar controller needed to have small transport X under the aircraft level at FL210 because small transport X was landing in the saginaw area. Supplemental information from acn 141819. Small transport X FL230 15 southwest mop VOR landing D98. My D controller answering ho lines for me. My D controller told me small transport X was my control down on contact. On initial contact, small transport X requested lower. I descended him to FL110. Shortly after he left FL230 the conflict alert went off between small transport X and at FL220, I turned small transport X to a 360 degree heading and told him to expedite his descent through FL210 and issued him traffic. Small transport X reported leaving FL210, was on ZAU fremont sectors frequency. So there was no way I could turn him. Air carrier Y was well north of his cleared route of flight. J16. If air carrier Y would have been on J16, a system error would not have occurred. If the lan D controller would have told me small transport X was my control down reference air carrier Y, as he had coordination with chicago, fremont sector, a system error would not have occurred. Did chicago fremont sector turn air carrier Y north of course?

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Original NASA ASRS Text

Title: SMT X HAD LESS THAN STANDARD SEPARATION FROM ACR Y. SYSTEM ERROR.

Narrative: SMT X WAS LEVEL AT FL230. ACR Y WAS LEVEL AT FL220. SMT X DEST WAS 78D. I RECEIVED PERMISSION FROM ZAU TO DSND SMT X, WHO WAS EBND, WITH RESPECT TO ACR Y, WHO WAS WBND. I INFORMED THE RADAR CTLR THAT SMT X WAS HIS CTL FOR DSNT. I DID NOT MENTION ACR Y BECAUSE THE ACFT WAS ON THE SCOPE IN OUR SECTOR. I ANSWERED SEVERAL CALLS FROM ZAU AND DID NOT HEAR THE RADAR CTLR ISSUE A LOWER ALT TO SMT X. WHEN I REALIZED THAT SMT X WAS DSNDING HEAD ON AT ACR Y, THE RADAR CTLR HAD ALREADY TAKEN CORRECTIVE ACTION. A MAJOR FACTOR WAS AN ACFT LEVEL AT FL210 SBND. THE RADAR CTLR NEEDED TO HAVE SMT X UNDER THE ACFT LEVEL AT FL210 BECAUSE SMT X WAS LNDG IN THE SAGINAW AREA. SUPPLEMENTAL INFO FROM ACN 141819. SMT X FL230 15 SW MOP VOR LNDG D98. MY D CTLR ANSWERING HO LINES FOR ME. MY D CTLR TOLD ME SMT X WAS MY CTL DOWN ON CONTACT. ON INITIAL CONTACT, SMT X REQUESTED LOWER. I DSNDED HIM TO FL110. SHORTLY AFTER HE LEFT FL230 THE CONFLICT ALERT WENT OFF BTWN SMT X AND AT FL220, I TURNED SMT X TO A 360 DEG HDG AND TOLD HIM TO EXPEDITE HIS DSNT THROUGH FL210 AND ISSUED HIM TFC. SMT X RPTED LEAVING FL210, WAS ON ZAU FREMONT SECTORS FREQ. SO THERE WAS NO WAY I COULD TURN HIM. ACR Y WAS WELL N OF HIS CLRED RTE OF FLT. J16. IF ACR Y WOULD HAVE BEEN ON J16, A SYS ERROR WOULD NOT HAVE OCCURRED. IF THE LAN D CTLR WOULD HAVE TOLD ME SMT X WAS MY CTL DOWN REF ACR Y, AS HE HAD COORD WITH CHICAGO, FREMONT SECTOR, A SYS ERROR WOULD NOT HAVE OCCURRED. DID CHICAGO FREMONT SECTOR TURN ACR Y N OF COURSE?

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.