Narrative:

At approximately XA21Z, 11 DME southwest of mdw at 3300', descending to 3000'. Radar vectors mdw I spotted a single engine small aircraft at 12 O'clock position just below the nose of my aircraft. We were in a very shallow descent leveling at 3000'. The first officer was flying the aircraft and I pointed out the traffic and made a gradual left turn, about 20 degrees left. Chicago approach at this time gave us a right turn to ? Which I could not accept due to the traffic. I was then asked what I wanted for a heading. I replied with either present heading or left turn. We were then assigned heading 180 degrees. I had been on assigned heading 290 degrees for the vector to runway 4R mdw and had already turned to a 270 degree heading to avoid the conflict traffic in order to keep him in sight in case he made a turn towards us. He, the small aircraft, was level at 3000' and approximately heading of 290 degrees. The controller was very busy and had not given any advisories and later said he did not see the other traffic until after we had already passed clear of it. Luckily the other aircraft was spotted in ample time to avoid any abrupt maneuvers. Perfect set up for midair. Clear, visibility unlimited, holiday weekend and a very busy controller. Discovered by outside vigilance on behalf of crew. Corrective action: guess we need to upgrade the systems, more full performance controllers, and I hate to say it, but if an small aircraft (or for that matter, large planes) operate in the vicinity of busy terminal areas, they need to have the appropriate equipment in proper working order.

Related reports:

Google
 

Original NASA ASRS Text

Title: POTENTIAL CONFLICT AIRBORNE BETWEEN ACR-MLG AND GA-SMA.

Narrative: AT APPROX XA21Z, 11 DME SW OF MDW AT 3300', DSNDING TO 3000'. RADAR VECTORS MDW I SPOTTED A SINGLE ENG SMA AT 12 O'CLOCK POS JUST BELOW THE NOSE OF MY ACFT. WE WERE IN A VERY SHALLOW DSCNT LEVELING AT 3000'. THE F/O WAS FLYING THE ACFT AND I POINTED OUT THE TFC AND MADE A GRADUAL LEFT TURN, ABOUT 20 DEGS LEFT. CHICAGO APCH AT THIS TIME GAVE US A RIGHT TURN TO ? WHICH I COULD NOT ACCEPT DUE TO THE TFC. I WAS THEN ASKED WHAT I WANTED FOR A HDG. I REPLIED WITH EITHER PRESENT HDG OR LEFT TURN. WE WERE THEN ASSIGNED HDG 180 DEGS. I HAD BEEN ON ASSIGNED HDG 290 DEGS FOR THE VECTOR TO RWY 4R MDW AND HAD ALREADY TURNED TO A 270 DEG HDG TO AVOID THE CONFLICT TFC IN ORDER TO KEEP HIM IN SIGHT IN CASE HE MADE A TURN TOWARDS US. HE, THE SMA, WAS LEVEL AT 3000' AND APPROX HDG OF 290 DEGS. THE CTLR WAS VERY BUSY AND HAD NOT GIVEN ANY ADVISORIES AND LATER SAID HE DID NOT SEE THE OTHER TFC UNTIL AFTER WE HAD ALREADY PASSED CLR OF IT. LUCKILY THE OTHER ACFT WAS SPOTTED IN AMPLE TIME TO AVOID ANY ABRUPT MANEUVERS. PERFECT SET UP FOR MIDAIR. CLEAR, VIS UNLIMITED, HOLIDAY WEEKEND AND A VERY BUSY CTLR. DISCOVERED BY OUTSIDE VIGILANCE ON BEHALF OF CREW. CORRECTIVE ACTION: GUESS WE NEED TO UPGRADE THE SYSTEMS, MORE FULL PERFORMANCE CTLRS, AND I HATE TO SAY IT, BUT IF AN SMA (OR FOR THAT MATTER, LARGE PLANES) OPERATE IN THE VICINITY OF BUSY TERMINAL AREAS, THEY NEED TO HAVE THE APPROPRIATE EQUIP IN PROPER WORKING ORDER.

Data retrieved from NASA's ASRS site as of August 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.