TCASII RA causes evasion of traffic closing in IMC.

Attributes
ACN	241690
Time
Date	199305
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : cvg
State Reference	OH
Altitude	msl bound lower : 7500 msl bound upper : 8000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : cvg
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument pilot : flight engineer
Experience	flight time last 90 days : 200 flight time total : 8000 flight time type : 1800
ASRS Report	241690
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation non adherence : far
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Pilot Deviation Operational Error

Narrative:

Normal descent into cvg area. While on vectors at 8000 ft, we received a TCASII TA. Since we were in the clouds, we immediately looked for the traffic in the radar scope (autoplt on). We saw a return, ahead, level and closing in. A few seconds later, we received an RA, commanding a 2000 FPM descent. I disconnected the autoplt and immediately descended at 2000 FPM to 7500 ft. At this time, the RA ended. We climbed back to 8000 ft while notifying the controller. We did not know how close we were from the aircraft, but I feel that TCASII saved us.

Original NASA ASRS Text

Title: TCASII RA CAUSES EVASION OF TFC CLOSING IN IMC.

Narrative: NORMAL DSCNT INTO CVG AREA. WHILE ON VECTORS AT 8000 FT, WE RECEIVED A TCASII TA. SINCE WE WERE IN THE CLOUDS, WE IMMEDIATELY LOOKED FOR THE TFC IN THE RADAR SCOPE (AUTOPLT ON). WE SAW A RETURN, AHEAD, LEVEL AND CLOSING IN. A FEW SECONDS LATER, WE RECEIVED AN RA, COMMANDING A 2000 FPM DSCNT. I DISCONNECTED THE AUTOPLT AND IMMEDIATELY DSNDED AT 2000 FPM TO 7500 FT. AT THIS TIME, THE RA ENDED. WE CLBED BACK TO 8000 FT WHILE NOTIFYING THE CTLR. WE DID NOT KNOW HOW CLOSE WE WERE FROM THE ACFT, BUT I FEEL THAT TCASII SAVED US.

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.