ZAU experienced loss of separation resulting from inadequate intrafac coordination efforts.

Attributes
ACN	590053
Time
Date	200308
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : zau.artcc
State Reference	IL
Altitude	msl single value : 17000
Environment
Flight Conditions	IMC
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : zau.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zau.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise : level descent : intermediate altitude descent : vacating altitude
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 17
ASRS Report	590053
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	atc equipment : conflict alert other controllera
Resolutory Action	none taken : anomaly accepted
Consequence	faa : investigated
Miss Distance	horizontal : 21000 vertical : 200
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

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.

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.