ZOB controller experienced operational error at FL310 with descend and en route aircraft.

Attributes
ACN	656322
Time
Date	200504
Place
Locale Reference	atc facility : zob.artcc
State Reference	OH
Altitude	msl single value : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob.artcc
Operator	common carrier : air carrier
Make Model Name	EMB ERJ 145 ER&LR
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	Regional Jet 200 ER&LR
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar instruction : trainee
Qualification	controller : developmental
Experience	controller non radar : 6 controller radar : 4
ASRS Report	656322
Person 2
Affiliation	government : faa
Function	controller : radar instruction : instructor
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	atc equipment : conflict alert other controllera
Resolutory Action	controller : issued new clearance controller : issued alert
Consequence	faa : investigated
Miss Distance	horizontal : 21600
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Needed to have aircraft descend. Thought there was separation with en route aircraft. Turns were issued; but separation was lost.

Original NASA ASRS Text

Title: ZOB CTLR EXPERIENCED OPERROR AT FL310 WITH DSND AND ENRTE ACFT.

Narrative: NEEDED TO HAVE ACFT DSND. THOUGHT THERE WAS SEPARATION WITH ENRTE ACFT. TURNS WERE ISSUED; BUT SEPARATION WAS LOST.

Data retrieved from NASA's ASRS site as of January 2009 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.