An air carrier medium large transport turned right to avoid a VFR aircraft.

Attributes
ACN	268141
Time
Date	199404
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : cvg
State Reference	OH
Altitude	msl bound lower : 12000 msl bound upper : 12000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise other
Route In Use	arrival other arrival star : star enroute airway : cvg
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	climbout : intermediate altitude
Route In Use	departure 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 : 99 flight time total : 10000 flight time type : 1000
ASRS Report	268141
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	non adherence : clearance other anomaly other other spatial deviation
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 5000 vertical : 400
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Arrival into cvg on blunt 8 -- approaching blunt intersection at 12000 ft and 250 KIAS. TCASII indicated an aircraft approaching more or less head on and climbing through 11300 ft. We acquired it visually and determined it to be a light twin. By the time ATC called out traffic to us, we had already started a turn to the right. TCASII indicated the twin still climbing through 11600 ft at a distance of less than 1 mi. ATC's traffic call referred to the twin as climbing to 11500 ft. This indicates to me a planned proximity of 500 ft separation on an arrival into a very busy airport. TCASII was indicating a climb to avoid the conflict and, under IMC, would have dictated that action. Any departure from altitude which is initiated as an evasive maneuver would logically involve at least 3-500 ft which appears to be the planned margin of separation into cvg. The twin would have passed directly under us if we had not turned and if it had maintained 11500 ft. This means that no horizontal separation was planned at all. Scattered clouds in the area permitted VFR operations but could have also contributed to no visual contact. An earlier ATC call on the traffic would not have helped us find the twin visually any quicker.

Original NASA ASRS Text

Title: AN ACR MLG TURNED R TO AVOID A VFR ACFT.

Narrative: ARR INTO CVG ON BLUNT 8 -- APCHING BLUNT INTXN AT 12000 FT AND 250 KIAS. TCASII INDICATED AN ACFT APCHING MORE OR LESS HEAD ON AND CLBING THROUGH 11300 FT. WE ACQUIRED IT VISUALLY AND DETERMINED IT TO BE A LIGHT TWIN. BY THE TIME ATC CALLED OUT TFC TO US, WE HAD ALREADY STARTED A TURN TO THE R. TCASII INDICATED THE TWIN STILL CLBING THROUGH 11600 FT AT A DISTANCE OF LESS THAN 1 MI. ATC'S TFC CALL REFERRED TO THE TWIN AS CLBING TO 11500 FT. THIS INDICATES TO ME A PLANNED PROX OF 500 FT SEPARATION ON AN ARR INTO A VERY BUSY ARPT. TCASII WAS INDICATING A CLB TO AVOID THE CONFLICT AND, UNDER IMC, WOULD HAVE DICTATED THAT ACTION. ANY DEP FROM ALT WHICH IS INITIATED AS AN EVASIVE MANEUVER WOULD LOGICALLY INVOLVE AT LEAST 3-500 FT WHICH APPEARS TO BE THE PLANNED MARGIN OF SEPARATION INTO CVG. THE TWIN WOULD HAVE PASSED DIRECTLY UNDER US IF WE HAD NOT TURNED AND IF IT HAD MAINTAINED 11500 FT. THIS MEANS THAT NO HORIZ SEPARATION WAS PLANNED AT ALL. SCATTERED CLOUDS IN THE AREA PERMITTED VFR OPS BUT COULD HAVE ALSO CONTRIBUTED TO NO VISUAL CONTACT. AN EARLIER ATC CALL ON THE TFC WOULD NOT HAVE HELPED US FIND THE TWIN VISUALLY ANY QUICKER.

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.