VISUAL APCH CGX HAS POTENTIAL CONFLICT WITH MLG ON SID OUT OF MDW.

Narrative

WHEN THE INCIDENT OCCURRED WE HAD BEEN CLRED FOR A VISUAL APCH TO RWY 36 AT CGX. AT APPROX 1600' MSL; AS I RECALL; I CALLED FOR 60% FLAPS. WHEN MY COPLT REACHED FOR THE FLAP ACTIVATOR HANDLE; HE CAUGHT SIGHT OF AN MLG THROUGH MY SIDE WINDOW. THE MLG LOOKED TO BE AT OUR EXACT ALT AND AIMED STRAIGHT AT US. ALTHOUGH I ESTIMATED THE MLG TO BE 1-2 MI AWAY; I DIDN'T BELIEVE IT TO BE OF ANY SIGNIFICANCE AS FAR AS SAFETY TO OUR PARTICULAR FLT WAS CONCERNED--BUT WE DID QUESTION THE MLG ALT AND WONDERED WHY HE WAS THAT CLOSE. WE WERE LATER TOLD THAT THE MLG WAS ON A CANAL 3 DEP FROM MDW. I THINK THE CANAL 3 SID SHOULD BE REWRITTEN TO PREVENT CONFLICTS WITH THE ATA AT CGX. 91.87 D(1) PRESCRIBES TFC PATTERN ALT FOR TURBINE ACFT TO BE 1500' AGL; 2100' MSL. A LARGE PORTION OF ACFT USING CGX ARE TURBINE ACFT. THE SID CALLS FOR DEPARTING ACFT (DME EQUIPPED) TO STAY AT 2000' MSL UNTIL 6 DME FROM MDW; WHICH PUTS THEM STILL AT 2000' MSL ABOUT 1 MI W OF CGX AND INDICATING 200 KIAS. I WOULD SUGGEST ALL DEPS FROM MDW USE THE MDW 3 DEP EXCEPT THAT EBND TFC CLB IMMEDIATELY TO 3100' MSL OR ASSIGNED HIGHER.