Narrative:

Aircraft #2 was wbound at FL200. Aircraft #1 was sebound at FL210. Aircraft #1 needed a descent clearance to FL190 to meet a LOA with ZID and to avoid a conflict with a nebound jet at FL210. In concentrating on these issues, I somehow overlooked the potential conflict with the aircraft #2. By the time I discovered the error, standard separation was lost. Traffic was issued and vector heading was issued to aircraft #1 to maximize the existing separation. Aircraft #1 was also asked to expedite the descent. The error was discovered simultaneously by another controller at an adjacent sector and by 'conflict alert.' at the time of the error, traffic was light but was poised for the afternoon rush which began about 5 mins later. As I recall, there were only 4 or 5 aircraft on the frequency at the time.

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Original NASA ASRS Text

Title: ZAU DEVELOPMENTAL CTLR OVERLOOKS POTENTIAL OPPOSITE DIRECTION CONFLICT WHEN DSNDING AN ACR TO MEET LOA REQUIREMENTS.

Narrative: ACFT #2 WAS WBOUND AT FL200. ACFT #1 WAS SEBOUND AT FL210. ACFT #1 NEEDED A DSCNT CLRNC TO FL190 TO MEET A LOA WITH ZID AND TO AVOID A CONFLICT WITH A NEBOUND JET AT FL210. IN CONCENTRATING ON THESE ISSUES, I SOMEHOW OVERLOOKED THE POTENTIAL CONFLICT WITH THE ACFT #2. BY THE TIME I DISCOVERED THE ERROR, STANDARD SEPARATION WAS LOST. TFC WAS ISSUED AND VECTOR HDG WAS ISSUED TO ACFT #1 TO MAXIMIZE THE EXISTING SEPARATION. ACFT #1 WAS ALSO ASKED TO EXPEDITE THE DSCNT. THE ERROR WAS DISCOVERED SIMULTANEOUSLY BY ANOTHER CTLR AT AN ADJACENT SECTOR AND BY 'CONFLICT ALERT.' AT THE TIME OF THE ERROR, TFC WAS LIGHT BUT WAS POISED FOR THE AFTERNOON RUSH WHICH BEGAN ABOUT 5 MINS LATER. AS I RECALL, THERE WERE ONLY 4 OR 5 ACFT ON THE FREQ AT THE TIME.

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.