Narrative:

I was working the bvt high sector at ZAU when I climbed aircraft X through aircraft Y. I felt that I would have appropriate lateral separation, except aircraft X was drifting east of the centerline of J89, northwest of bvt. I turned aircraft X to a 170 degree heading. When that did not appear to work, I turned aircraft Y 20 degrees right. The aircraft appeared to pass within 4.5 to 5 mi laterally.

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Original NASA ASRS Text

Title: ARTCC RADAR CTLR MISJUDGES LATERAL SPACING NEEDED WHEN CLBING AN ACFT IN FRONT AND THROUGH THE ALT OF ANOTHER ACR ACFT AT CRUISE ALT. RECOGNIZING INSUFFICIENT LATERAL DISTANCE, THE CTLR ISSUED TURNS, BUT WAS UNABLE TO MAINTAIN LEGAL SEPARATION.

Narrative: I WAS WORKING THE BVT HIGH SECTOR AT ZAU WHEN I CLBED ACFT X THROUGH ACFT Y. I FELT THAT I WOULD HAVE APPROPRIATE LATERAL SEPARATION, EXCEPT ACFT X WAS DRIFTING E OF THE CTRLINE OF J89, NW OF BVT. I TURNED ACFT X TO A 170 DEG HDG. WHEN THAT DID NOT APPEAR TO WORK, I TURNED ACFT Y 20 DEGS R. THE ACFT APPEARED TO PASS WITHIN 4.5 TO 5 MI LATERALLY.

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.