Converging VFR and IFR traffic in the chicago approach area.

Attributes
ACN	523850
Time
Date	200109
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : ord.airport
State Reference	IL
Altitude	msl single value : 11300
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tower : atl.tower
Operator	common carrier : air carrier
Make Model Name	MD-80 Super 80
Flight Phase	descent : intermediate altitude
Route In Use	arrival star : bradford
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : c90.tracon
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	descent : intermediate altitude
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	523850
Events
Anomaly	conflict : airborne critical
Resolutory Action	controller : issued advisory flight crew : took evasive action
Supplementary
Problem Areas	Airspace Structure Flight Crew Human Performance ATC Human Performance
Primary Problem	Airspace Structure

Narrative:

At 11300 ft descending to 11000 ft, received descending RA. Responded to RA. ATC called VFR traffic at 12 O'clock position, 12000 ft and descending. Oncoming traffic made a climbing right turn. Aircraft crossed within 200 ft and 1 mi of each other. VFR traffic appeared to be a twin engine cpr jet. ATC said aircraft quickly descended and disappeared off radar screen at 4000 ft.

Original NASA ASRS Text

Title: CONVERGING VFR AND IFR TFC IN THE CHICAGO APCH AREA.

Narrative: AT 11300 FT DSNDING TO 11000 FT, RECEIVED DSNDING RA. RESPONDED TO RA. ATC CALLED VFR TFC AT 12 O'CLOCK POS, 12000 FT AND DSNDING. ONCOMING TFC MADE A CLBING R TURN. ACFT CROSSED WITHIN 200 FT AND 1 MI OF EACH OTHER. VFR TFC APPEARED TO BE A TWIN ENG CPR JET. ATC SAID ACFT QUICKLY DSNDED AND DISAPPEARED OFF RADAR SCREEN AT 4000 FT.

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.