DC9 flight crew advises cvg of TCASII conflict with what appears to the controller as an unknown VFR...

Attributes
ACN	450027
Time
Date	199909
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : cvg.airport
State Reference	KY
Altitude	msl single value : 12000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : cvg.tracon tower : ord.tower
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Flight Plan	VFR
Aircraft 2
Controlling Facilities	tracon : cvg.tracon
Operator	common carrier : air carrier
Make Model Name	Challenger CL604
Operating Under FAR Part	Part 121
Flight Phase	climbout : vacating altitude
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : departure
Qualification	controller : radar
ASRS Report	450027
Person 2
Function	flight crew : single pilot
Qualification	pilot : private
Events
Anomaly	conflict : airborne less severe
Independent Detector	atc equipment : conflict alert aircraft equipment : tcas other controllera other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 3000 vertical : 500
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance Airspace Structure
Primary Problem	Ambiguous

Narrative:

While working a departure position, I climbed a carj (aircraft X) to 13000 ft, northeast of cvg, in reference to 2 other departures. One aircraft (aircraft Y) was climbing the same direction below the carj, while another aircraft was climbing opposite direction. I stopped the opposite direction DC9 (aircraft Z) to 10000 ft, keeping it below the climbing carj and above the second clber nebound. As all 3 data blocks overlapped, my conflict alert went off. At that time the carj asked if there was traffic in his area as his RA went off from his TCASII. I then advised him of traffic that I observed that had just passed off his right indicating 12500 ft. He said that traffic was about 1/2 mi from his position.

Original NASA ASRS Text

Title: DC9 FLC ADVISES CVG OF TCASII CONFLICT WITH WHAT APPEARS TO THE CTLR AS AN UNKNOWN VFR ACFT.

Narrative: WHILE WORKING A DEP POS, I CLBED A CARJ (ACFT X) TO 13000 FT, NE OF CVG, IN REF TO 2 OTHER DEPS. ONE ACFT (ACFT Y) WAS CLBING THE SAME DIRECTION BELOW THE CARJ, WHILE ANOTHER ACFT WAS CLBING OPPOSITE DIRECTION. I STOPPED THE OPPOSITE DIRECTION DC9 (ACFT Z) TO 10000 FT, KEEPING IT BELOW THE CLBING CARJ AND ABOVE THE SECOND CLBER NEBOUND. AS ALL 3 DATA BLOCKS OVERLAPPED, MY CONFLICT ALERT WENT OFF. AT THAT TIME THE CARJ ASKED IF THERE WAS TFC IN HIS AREA AS HIS RA WENT OFF FROM HIS TCASII. I THEN ADVISED HIM OF TFC THAT I OBSERVED THAT HAD JUST PASSED OFF HIS R INDICATING 12500 FT. HE SAID THAT TFC WAS ABOUT 1/2 MI FROM HIS POS.

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.

DC9 flight crew advises cvg of TCASII conflict with what appears to the controller as an unknown VFR aircraft.