Narrative:

Despite good weather condition; a haze restricted consistent visual approaches; especially from the east over lake michigan. I prepared aircraft X for a close in visual approach; reduced their speed and descended them to the floor of the class B. When in proper position; prior to the shoreline I turned their base; calling VFR traffic over the water; and the airport. Aircraft X saw the airport without issue. I advised that I would have their turn and clearance once they got a little lower. Our SOP requires a 30 degree intercept heading be issued to ensure that aircraft don't overshoot the final; due to the triple finals being utilized.had I turned aircraft X when they saw the airport; they would have been above glideslope altitude and the 30 degree intercept would have joined the final inside the marker. To allow for a stable approach I opted to withhold the clearance until they got closer to the visual box (lines on airspace which denotes 3 miles from the center runway. Traffic volume was low; however more complex due to the inconsistency in the weather. While aircraft X continued on base; aircraft Y checked in. I then spoke with another aircraft. At about the time I should have been clearing aircraft X; aircraft Y asked if runway 27L was available. I quick looked at the Z final to ascertain their volume; and told them I would check. In the meantime I failed to issue the turn and clearance to aircraft X. I returned to an airport out scan; noticed eny wasn't turning; and at that moment thought I had issued the clearance but they hadn't turned. So I reissued the turn and clearance. At this point; upon acknowledgement of the turn and clearance separation with another aircraft on runway 27L (the 1z1 position) had been lost; and was found to be a little more than 2 miles and 300 feet. Due to the close proximity the localizer aircraft X went across.I then went to my bottom strip and saw I hadn't lined through the altitude (my reminder an approach clearance had been issued). After review; the clearance hadn't been given previously as I had thought. So I then realized the fact that aircraft X was definitely going to go through; so reissued the clearance; along with an immediate descent and hard turn back to a 290 degree heading to rejoin their final. At the time; I hadn't noticed the conflict alert going off. We have had issues with the conflict alert since stars has been installed; including nuisance alerts. After reviewing the situation; it was noted that the conflict alert didn't alert until the aircraft were converging; 2.38 miles apart and 300 feet. I feel this is worth noting not because conflict alert was the cause; but that conflict alert didn't alert in a timely fashion to help avert an issue. Both aircraft did report responding to RA's. Currently our SOP just requires us to attain a visual approach clearance acknowledgement; and 30 degree turn prior to losing standard separation with the other runway. But due to weather phenomena related to the shoreline/lake michigan; airspace issues relating to the class B and midway arrival and departures; and MVA with the sears tower; visual approaches can be difficult to obtain. Also; both runway 28C and 27R run opposite bases descending to the same altitude; typically pointed at each other. This is found to be ok because runway 27L is in between. But typically; the runway 27L traffic is descending out of similar altitudes on the ILS that the two opposite bases are at or descending to. This leaves little margin for error. In this case; I was running a precision operation that required a timely clearance; which I didn't deliver. However; a better set-up procedure may have prevented these two airplanes from being so dangerously close. One potential recommendation would be for the outboard runways to run; widely spaced; dependent ILS approaches without monitors; turning on at 4;000 feet and 5;000 feet. The center runway would run visual approaches; at or above 6;000 on the straight in. In the event visuals aren't feasible prior to the 6;000 foot fix; then triple simultaneous approaches should be ran. To further maximize efficiency; if the floor of the bravo was expanded to 20 miles at 3;000; or the 1f1 airspace expanded to 3;000 to the 20 NM range ring; ILS approaches on the outer runways can be run at 3;000 feet and 4;000 feet; allowing visuals by the 5;000 foot fix on the center runway.

Google
 

Original NASA ASRS Text

Title: C90 TRACON Controller forgot to turn an aircraft onto the final approach course. The aircraft proceeded into confliction with parallel runway traffic.

Narrative: Despite good weather condition; a haze restricted consistent visual approaches; especially from the east over Lake Michigan. I prepared Aircraft X for a close in visual approach; reduced their speed and descended them to the floor of the Class B. When in proper position; prior to the shoreline I turned their base; calling VFR traffic over the water; and the airport. Aircraft X saw the airport without issue. I advised that I would have their turn and clearance once they got a little lower. Our SOP requires a 30 degree intercept heading be issued to ensure that aircraft don't overshoot the final; due to the triple finals being utilized.Had I turned Aircraft X when they saw the airport; they would have been above glideslope altitude and the 30 degree intercept would have joined the final inside the marker. To allow for a stable approach I opted to withhold the clearance until they got closer to the visual box (lines on airspace which denotes 3 miles from the center runway. Traffic volume was low; however more complex due to the inconsistency in the weather. While Aircraft X continued on base; Aircraft Y checked in. I then spoke with another aircraft. At about the time I should have been clearing Aircraft X; Aircraft Y asked if RWY 27L was available. I quick looked at the Z final to ascertain their volume; and told them I would check. In the meantime I failed to issue the turn and clearance to Aircraft X. I returned to an airport out scan; noticed ENY wasn't turning; and at that moment thought I had issued the clearance but they hadn't turned. So I reissued the turn and clearance. At this point; upon acknowledgement of the turn and clearance separation with another aircraft on RWY 27L (the 1Z1 position) had been lost; and was found to be a little more than 2 miles and 300 feet. Due to the close proximity the localizer Aircraft X went across.I then went to my bottom strip and saw I hadn't lined through the altitude (my reminder an approach clearance had been issued). After review; the clearance hadn't been given previously as I had thought. So I then realized the fact that Aircraft X was definitely going to go through; so reissued the clearance; along with an immediate descent and hard turn back to a 290 degree heading to rejoin their final. At the time; I hadn't noticed the conflict alert going off. We have had issues with the conflict alert since STARS has been installed; including nuisance alerts. After reviewing the situation; it was noted that the conflict alert didn't alert until the aircraft were converging; 2.38 miles apart and 300 feet. I feel this is worth noting not because conflict alert was the cause; but that conflict alert didn't alert in a timely fashion to help avert an issue. Both aircraft did report responding to RA's. Currently our SOP just requires us to attain a visual approach clearance acknowledgement; and 30 degree turn prior to losing standard separation with the other runway. But due to weather phenomena related to the shoreline/Lake Michigan; airspace issues relating to the Class B and Midway arrival and departures; and MVA with the Sears Tower; Visual Approaches can be difficult to obtain. Also; both Runway 28C and 27R run opposite bases descending to the same altitude; typically pointed at each other. This is found to be ok because Runway 27L is in between. But typically; the Runway 27L traffic is descending out of similar altitudes on the ILS that the two opposite bases are at or descending to. This leaves little margin for error. In this case; I was running a precision operation that required a timely clearance; which I didn't deliver. However; a better set-up procedure may have prevented these two airplanes from being so dangerously close. One potential recommendation would be for the outboard runways to run; widely spaced; dependent ILS approaches without monitors; turning on at 4;000 feet and 5;000 feet. The center runway would run visual approaches; at or above 6;000 on the straight in. In the event visuals aren't feasible prior to the 6;000 foot fix; then triple simultaneous approaches should be ran. To further maximize efficiency; if the floor of the BRAVO was expanded to 20 miles at 3;000; or the 1F1 airspace expanded to 3;000 to the 20 NM range ring; ILS approaches on the outer runways can be run at 3;000 feet and 4;000 feet; allowing visuals by the 5;000 foot fix on the center runway.

Data retrieved from NASA's ASRS site 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.