Air carrier has near midair collision with VFR aircraft. TCASII alert stopped descent.

Attributes
ACN	209777
Time
Date	199205
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : cvg
State Reference	OH
Altitude	msl bound lower : 6500 msl bound upper : 7000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : cvg
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent : approach
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 200 flight time total : 500 flight time type : 400
ASRS Report	209777
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	conflict : nmac other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 0 vertical : 500
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

We were handed over to cvg approach during a descent to 5000 ft. Before we could check in with cvg approach, our attention was drawn to a TCASII alert. It showed an aircraft approaching from the right, and 500 ft below. We then got a traffic call from approach control but no altitude information or turn. We stopped our descent and then saw the aircraft pass under us, 500 ft below, no horizontal separation. If we hadn't stopped our descent, it is the opinion of myself and my copilot that the aircraft would have collided. I called the approach control supervisor. He told me that they knew the other aircraft's altitude was 6500 ft from mode C readout but didn't tell us because he was VFR and therefore his altitude was 'unverified.'

Original NASA ASRS Text

Title: ACR HAS NMAC WITH VFR ACFT. TCASII ALERT STOPPED DSCNT.

Narrative: WE WERE HANDED OVER TO CVG APCH DURING A DSCNT TO 5000 FT. BEFORE WE COULD CHK IN WITH CVG APCH, OUR ATTN WAS DRAWN TO A TCASII ALERT. IT SHOWED AN ACFT APCHING FROM THE R, AND 500 FT BELOW. WE THEN GOT A TFC CALL FROM APCH CTL BUT NO ALT INFO OR TURN. WE STOPPED OUR DSCNT AND THEN SAW THE ACFT PASS UNDER US, 500 FT BELOW, NO HORIZ SEPARATION. IF WE HADN'T STOPPED OUR DSCNT, IT IS THE OPINION OF MYSELF AND MY COPLT THAT THE ACFT WOULD HAVE COLLIDED. I CALLED THE APCH CTL SUPVR. HE TOLD ME THAT THEY KNEW THE OTHER ACFT'S ALT WAS 6500 FT FROM MODE C READOUT BUT DIDN'T TELL US BECAUSE HE WAS VFR AND THEREFORE HIS ALT WAS 'UNVERIFIED.'

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.