Narrative:

I was providing OJT (on job training) to a cpc-it on north local. The configuration was 'plan X' (landing runway's 4R; 10; and 9R and departing runway's 32L @ T10; 4L; 9R; 32R). North local is responsible for landing runway 9R and departing runway's 4L; 9R and 32R. During the time of the incident; we were landing and departing all available runways and had a medical helicopter in and out of a hospital in our airspace. During this specific event; the person I was training had air carrier X; at earnd (south) fix; in position on runway 4L and an aircraft landing runway 9R with air carrier Y; at dennt (south) fix holding short of runway 9R. As the arrival crossed the runway 9R threshold he told air carrier Y to position and hold on runway 9R with traffic departing runway 4L. He then cleared air carrier X for takeoff runway 4L with a right turn to heading 090 remain this frequency. He put the next aircraft at runway 4L into position and hold. He then gave exit instructions to the runway 9R arrival. After the runway 9R arrival cleared the runway he cleared air carrier Y for takeoff runway 9R turn right heading 140; (furthest south you can go off runway 9R to protect for the runway 4R arrivals). He then put the next aircraft at runway 9R into position and hold. When air carrier X was east of the airport with air carrier Y off the departure end of runway 9R turning to a 140 heading I told the trainee that it would have been better to start air carrier X off; runway heading on runway 4L to increase the space between him and air carrier Y since we needed 3 miles between the aircraft. Immediately after saying this; he turned air carrier X further right heading 120. Since this was closing the space more than the 090 heading I thought that he was going to leave air carrier X on the 120 heading outside of air carrier Y who was established on the 140 heading and ship them both to departure and call down to explain (a common out we use here). Then he keyed up and told air carrier X to turn left heading 180. I said 'left turn?' he then went back and told air carrier X to turn right heading 180 and to contact departure. I then immediately over keyed and told air carrier X to turn right heading 140 and contact departure as we had 3 miles but knew that a 180 heading would put the planes on a converging course that would result in less than 3 miles. Air carrier X then asked for the departure frequency without reading back the newly assigned 140 heading and the trainee issued the frequency. When I saw on the radar that air carrier X had turned to a 180 heading it appeared we still had more than 3 miles and I called down to the TRACON south departure sector to ask the controller to turn air carrier X back to the southeast. When I did; I heard air carrier X report the traffic in sight and heard the departure controller issue a maintain visual separation clearance. The departure controller then asked me to 'get out of his ear'; which I did thinking that the visual separation clearance was obtained prior to the 3 miles being lost. After getting off position and debriefing the trainee; I was notified by the supervisor that the TRACON had called back and asked us to check into these two airplanes. At a later time that night; they called back and said loss of separation. I am not sure exactly how far apart the planes were when the visual separation clearance was issued. It appeared to be close to 3 miles. Recommendation; I should have ensured a correct read back from the pilot of the 140 heading.

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Original NASA ASRS Text

Title: ORD Local Controller; providing OJT; described a loss of separation event involving multiple departures utilizing several runways when he failed to hear an incorrect heading readback resulting in the conflict.

Narrative: I was providing OJT (On Job Training) to a CPC-IT on North Local. The configuration was 'Plan X' (Landing Runway's 4R; 10; and 9R and departing Runway's 32L @ T10; 4L; 9R; 32R). North Local is responsible for Landing Runway 9R and Departing Runway's 4L; 9R and 32R. During the time of the incident; we were landing and departing all available runways and had a medical helicopter in and out of a hospital in our airspace. During this specific event; the person I was training had Air Carrier X; at EARND (south) fix; in position on Runway 4L and an aircraft landing Runway 9R with Air Carrier Y; at DENNT (south) fix holding short of Runway 9R. As the arrival crossed the Runway 9R threshold he told Air Carrier Y to position and hold on Runway 9R with traffic departing Runway 4L. He then cleared Air Carrier X for takeoff Runway 4L with a right turn to heading 090 remain this frequency. He put the next aircraft at Runway 4L into position and hold. He then gave exit instructions to the Runway 9R arrival. After the Runway 9R arrival cleared the runway he cleared Air Carrier Y for takeoff Runway 9R turn right heading 140; (furthest south you can go off Runway 9R to protect for the Runway 4R arrivals). He then put the next aircraft at Runway 9R into position and hold. When Air Carrier X was east of the airport with Air Carrier Y off the departure end of Runway 9R turning to a 140 heading I told the trainee that it would have been better to start Air Carrier X off; runway heading on Runway 4L to increase the space between him and Air Carrier Y since we needed 3 miles between the aircraft. Immediately after saying this; he turned Air Carrier X further right heading 120. Since this was closing the space more than the 090 heading I thought that he was going to leave Air Carrier X on the 120 heading outside of Air Carrier Y who was established on the 140 heading and ship them both to Departure and call down to explain (a common out we use here). Then he keyed up and told Air Carrier X to turn left heading 180. I said 'left turn?' He then went back and told Air Carrier X to turn right heading 180 and to contact Departure. I then immediately over keyed and told Air Carrier X to turn right heading 140 and contact Departure as we had 3 miles but knew that a 180 heading would put the planes on a converging course that would result in less than 3 miles. Air Carrier X then asked for the Departure frequency without reading back the newly assigned 140 heading and the Trainee issued the frequency. When I saw on the RADAR that Air Carrier X had turned to a 180 heading it appeared we still had more than 3 miles and I called down to the TRACON South Departure Sector to ask the Controller to turn Air Carrier X back to the Southeast. When I did; I heard Air Carrier X report the traffic in sight and heard the Departure Controller issue a maintain visual separation clearance. The Departure Controller then asked me to 'get out of his ear'; which I did thinking that the visual separation clearance was obtained prior to the 3 miles being lost. After getting off position and debriefing the Trainee; I was notified by the Supervisor that the TRACON had called back and asked us to check into these two airplanes. At a later time that night; they called back and said loss of separation. I am not sure exactly how far apart the planes were when the visual separation clearance was issued. It appeared to be close to 3 miles. Recommendation; I should have ensured a correct read back from the pilot of the 140 heading.

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.