It appears a BA46 at 13000 ft overtook an SF34 descending from 14000 ft to 11000 ft.

Attributes
ACN	565968
Time
Date	200210
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : djb.vortac
State Reference	OH
Altitude	msl bound lower : 11000 msl bound upper : 13000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob.artcc tower : cmi.tower
Operator	common carrier : air carrier
Make Model Name	SF 340A
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zob.artcc
Operator	common carrier : air carrier
Make Model Name	BAe 146 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : developmental
Experience	controller military : 9 controller non radar : 9 controller radar : 9.5 controller time certified in position2 : 8
ASRS Report	565968
Person 2
Affiliation	government : faa
Function	controller : radar
Events
Anomaly	conflict : airborne critical inflight encounter other non adherence : required legal separation
Independent Detector	atc equipment : conflict alert atc equipment other atc equipment : radar/ mode c other controllera other controllerb other flight crewa other flight crewb
Resolutory Action	flight crew : took evasive action
Miss Distance	horizontal : 21000 vertical : 400
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X, an SF340, was inbound to dtw from the southeast at 14000 ft. Approximately 7 mi in trail, air carrier Y, a BA46, was inbound to dtw at 13000 ft. Air carrier Y was originally at 14000 ft, but was descended to 13000 ft for other traffic. Controller was not aware that the second aircraft was a jet since he was handed off at the same altitude as the propeller from mfd sector. Air carrier X, the SF340, was descended from 13000 ft to 11000 ft. Separation was lost when air carrier Y overtook air carrier X. The conflict alert went off and air carrier Y was turned left heading 240 degrees and advised air carrier X to expedite descent.

Original NASA ASRS Text

Title: IT APPEARS A BA46 AT 13000 FT OVERTOOK AN SF34 DSNDING FROM 14000 FT TO 11000 FT.

Narrative: ACR X, AN SF340, WAS INBOUND TO DTW FROM THE SE AT 14000 FT. APPROX 7 MI IN TRAIL, ACR Y, A BA46, WAS INBOUND TO DTW AT 13000 FT. ACR Y WAS ORIGINALLY AT 14000 FT, BUT WAS DSNDED TO 13000 FT FOR OTHER TFC. CTLR WAS NOT AWARE THAT THE SECOND ACFT WAS A JET SINCE HE WAS HANDED OFF AT THE SAME ALT AS THE PROP FROM MFD SECTOR. ACR X, THE SF340, WAS DSNDED FROM 13000 FT TO 11000 FT. SEPARATION WAS LOST WHEN ACR Y OVERTOOK ACR X. THE CONFLICT ALERT WENT OFF AND ACR Y WAS TURNED L HDG 240 DEGS AND ADVISED ACR X TO EXPEDITE DSCNT.

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.