A DEP CTLR RPT ON A POTENTIAL CONFLICT BTWN 2 ACFT CLBING TO THE SAME ALT 8 MI SW OF ORD; IL.

Narrative

I WAS WORKING THE MDW SECTOR 3 POS RESPONSIBLE FOR MDW N AND W DEPS AND SEVERAL SMALL ARPTS SW OF O'HARE. AS PROCS DICTATE; I HAD A NBOUND JET DEPART; SO I COORDINATED A CLB TO 6000 FT WITH THE O'HARE SBOUND CTLR. I WAS TOLD TO GO UP UNDER HIS ONLY SBOUND. A FEW MOMENTS LATER; THE O'HARE S DEP CALLED BACK TELLING ME TO STAY UNDER HIS SECOND SBOUND DEP; JUST AIRBORNE. I TOLD HIM I COULD STAY AT 5000 FT SO HE COULD GET THE #2 SBOUND CLBING. I WAS BUSY WITH OTHER ACFT AND DID NOT GET BACK TO THE NBOUND AS QUICKLY AS I SHOULD HAVE TO CLB IT TO 6000 FT; AS THE ALT BECAME AVAILABLE. EVEN THOUGH I HAD POINTED OUT THE NBOUND TO THE O'HARE S DEP CTLR AND HE SHOULD HAVE SEEN MY TFC STILL AT 5000 FT (THE INITIAL ALT ALL ORD DEPS CLB TO); HE ALLOWED HIS THIRD SBOUND TO CLB TO 5000 FT INSTEAD OF STOPPING BELOW ME. THEN HE ISSUED A TIGHT L TURN FROM A 220 DEG HDG TO A 140 DEG HDG THAT BROUGHT THE REGIONAL JET INTO THE PATH OF MY NBOUND B727 BOTH AT 5000 FT. THE S CTLR CALLED ME AGAIN ASKING IF THE NBOUND WAS GOING UP. AT THAT MOMENT; I CLBED THE NBOUND TO 6000 FT AND ISSUED A TURN TO 040 DEGS TO STAY AWAY FROM #3 SBOUND; UNAWARE THAT TFC WAS TURNED INTO MINE. VISUAL SEPARATION WAS APPLIED WHEN THE ACFT WERE ABOUT 3 MI APART. THEY MISSED BY LESS THAN 1 MI AND 200 FT. CONFLICT ALERT DID NOT GO OFF UNTIL THE ACFT STARTED COMING APART.