Narrative:

Air carrier Y was started down for descent into ord. Conflict alert was activated for another aircraft. Aircraft Z descending into mke. I stopped air carrier Y on top off the mke arrival. The next sector had the handoff coordination accomplished regarding the altitude. The aircraft air carrier Y was placed on the next controller frequency. Air carrier Y lost separation with another aircraft air carrier X, that was in the next controller's airspace and on his frequency. I was unaware of the traffic. Do not approve an altitude that would allow an aircraft entering your airspace to be in conflict with another.

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Original NASA ASRS Text

Title: ZAU EXPERIENCED LOSS OF SEPARATION RESULTING FROM INADEQUATE INTRAFAC COORD EFFORTS.

Narrative: ACR Y WAS STARTED DOWN FOR DSCNT INTO ORD. CONFLICT ALERT WAS ACTIVATED FOR ANOTHER ACFT. ACFT Z DESCENDING INTO MKE. I STOPPED ACR Y ON TOP OFF THE MKE ARR. THE NEXT SECTOR HAD THE HDOF COORD ACCOMPLISHED REGARDING THE ALT. THE ACFT ACR Y WAS PLACED ON THE NEXT CTLR FREQ. ACR Y LOST SEPARATION WITH ANOTHER ACFT ACR X, THAT WAS IN THE NEXT CTLR'S AIRSPACE AND ON HIS FREQ. I WAS UNAWARE OF THE TFC. DO NOT APPROVE AN ALT THAT WOULD ALLOW AN ACFT ENTERING YOUR AIRSPACE TO BE IN CONFLICT WITH ANOTHER.

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.