ZAU controller observes CL60 overtake a DC9 and attempts vectors to separate conflicting aircraft.

Attributes
ACN	511124
Time
Date	200105
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : jvl.vortac
State Reference	WI
Altitude	msl single value : 15000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zau.artcc tracon : c90.tracon
Operator	common carrier : air carrier
Make Model Name	DC-9 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	arrival : on vectors arrival star : jvl 4
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zau.artcc
Operator	common carrier : air carrier
Make Model Name	Challenger CL600
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	arrival : on vectors arrival star : jvl 4
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 15 flight time total : 20
ASRS Report	511124
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	atc equipment : conflict alert atc equipment other atc equipment : radar other controllera
Resolutory Action	controller : issued new clearance controller : separated traffic
Consequence	faa : investigated
Miss Distance	horizontal : 22200 vertical : 0
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I saw the CL60 overtaking the DC9 and assigned a speed of 250 KTS, which the CL60 seemed to take a while to slow. So I issued 30 degrees left to the DC9 and 30 degrees right to the CL60 to try to keep separation. I also expedited the DC9 down.

Original NASA ASRS Text

Title: ZAU CTLR OBSERVES CL60 OVERTAKE A DC9 AND ATTEMPTS VECTORS TO SEPARATE CONFLICTING ACFT.

Narrative: I SAW THE CL60 OVERTAKING THE DC9 AND ASSIGNED A SPD OF 250 KTS, WHICH THE CL60 SEEMED TO TAKE A WHILE TO SLOW. SO I ISSUED 30 DEGS L TO THE DC9 AND 30 DEGS R TO THE CL60 TO TRY TO KEEP SEPARATION. I ALSO EXPEDITED THE DC9 DOWN.

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.