FK10 crew had a TCASII RA in ord class B.

Attributes
ACN	460683
Time
Date	200001
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	intersection : devon
State Reference	IL
Altitude	msl single value : 6500
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : c90.tracon artcc : zfw.artcc
Operator	common carrier : air carrier
Make Model Name	Fokker 100
Operating Under FAR Part	Part 121
Flight Phase	descent : vacating altitude
Route In Use	arrival : on vectors
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : c90.tracon
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	climbout : vacating altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	460683
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : multi engine pilot : commercial
Events
Anomaly	conflict : airborne critical non adherence : published procedure non adherence : far
Independent Detector	aircraft equipment : tcas other flight crewa other flight crewb
Resolutory Action	flight crew : took evasive action
Miss Distance	vertical : 500
Supplementary
Problem Areas	Airspace Structure ATC Human Performance Weather
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

TCASII RA. During vectoring for approach to runway 9L, descent clearance out of 8000 ft to 5000 ft was given. Passing 6500 ft during the descent, I noticed traffic below us approximately 1100 ft lower and climbing. Shortly afterward a 'climb, climb' command was given. My copilot disconnected the autoplt and complied with the TCASII commands. ATC was notified as a climb back towards 6500 ft was initiated. After clear of conflict descent was resumed to 5000 ft. I notified ATC and their response was that they noticed the conflict but could not get through to us due to the radio traffic. We never saw the traffic as we were IMC, however, both the copilot and I both noticed the lowest separation was at most 500 ft. Thank you TCASII.

Original NASA ASRS Text

Title: FK10 CREW HAD A TCASII RA IN ORD CLASS B.

Narrative: TCASII RA. DURING VECTORING FOR APCH TO RWY 9L, DSCNT CLRNC OUT OF 8000 FT TO 5000 FT WAS GIVEN. PASSING 6500 FT DURING THE DSCNT, I NOTICED TFC BELOW US APPROX 1100 FT LOWER AND CLBING. SHORTLY AFTERWARD A 'CLB, CLB' COMMAND WAS GIVEN. MY COPLT DISCONNECTED THE AUTOPLT AND COMPLIED WITH THE TCASII COMMANDS. ATC WAS NOTIFIED AS A CLB BACK TOWARDS 6500 FT WAS INITIATED. AFTER CLR OF CONFLICT DSCNT WAS RESUMED TO 5000 FT. I NOTIFIED ATC AND THEIR RESPONSE WAS THAT THEY NOTICED THE CONFLICT BUT COULD NOT GET THROUGH TO US DUE TO THE RADIO TFC. WE NEVER SAW THE TFC AS WE WERE IMC, HOWEVER, BOTH THE COPLT AND I BOTH NOTICED THE LOWEST SEPARATION WAS AT MOST 500 FT. THANK YOU TCASII.

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.