A B737 experienced a near midair collision with a VFR C-210 on descent in the vicinity of mdw.

Attributes
ACN	853986
Time
Date	200910
Local Time Of Day	1201-1800
Place
Locale Reference	MDW.Airport
State Reference	IL
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	Vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Cessna 210 Centurion / Turbo Centurion 210C 210D
Person 1
Function	First Officer
Experience	Flight Crew Last 90 Days 233 Flight Crew Type 12000
Person 2
Function	Captain
Experience	Flight Crew Last 90 Days 189
Events
Anomaly	Conflict NMAC
Miss Distance	Horizontal 150

Narrative:

Descending through 3500 feet approximately 6 miles south of mdw; I observed a cessna 210 less than 300 feet from our right wing. I told ATC of this event immediately and controller stated he just popped up. The cessna made a right turn northbound after the event.

Original NASA ASRS Text

Title: A B737 experienced a NMAC with a VFR C-210 on descent in the vicinity of MDW.

Narrative: Descending through 3500 feet approximately 6 miles south of MDW; I observed a Cessna 210 less than 300 feet from our right wing. I told ATC of this event immediately and Controller stated he just popped up. The Cessna made a right turn northbound after the event.

Data retrieved from NASA's ASRS site as of April 2012 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.