Narrative:

Using noise abatement procedures in the morning; I cleared air carrier X for takeoff and waited longer than usual to clear air carrier Y behind him due to the procedures. Both pilots were told 'leaving 3000 feet turn right heading 040'. Air carrier X dogged the turn while air carrier Y made a tight turn. After I shipped air carrier X; I watched air carrier Y turn and saw that he was turning inside of air carrier X. In my estimation; had I turned air carrier Y back to the north he would have been in direct conflict and at the same altitude as air carrier X creating a dangerous situation. I had no more room to turn air carrier Y to the right; so I called traffic and when air carrier Y called traffic in sight; I told him to maintain visual separation. At that point; I heard a beep in my ear as if TRACON was calling to coordinate but no one said anything. I figured they heard me calling traffic and getting visual and would help out by turning or climbing air carrier X. I let it play out for another couple of miles and when the air carrier X didn't turn or climb I restated to air carrier Y to maintain visual separation and that air carrier X would be paralleling his course for a couple miles. Then I input the heading on the strip and added visual separation so TRACON would know. Noise abatement is probably nice for the people living around the airport; but it ties the hands of the controllers. Because you can't control how tight a pilot will turn; as in this instance; if the first pilot takes an easy turn and the second pilot a tight turn; you are left with no other out other than to maintain visual separation or coordinate a different heading with TRACON.

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Original NASA ASRS Text

Title: ORD Tower Local Controller complying with noise abatement procedures reported a loss of separation between successive departures.

Narrative: Using noise abatement procedures in the morning; I cleared Air Carrier X for takeoff and waited longer than usual to clear Air Carrier Y behind him due to the procedures. Both pilots were told 'leaving 3000 feet turn right heading 040'. Air Carrier X dogged the turn while Air Carrier Y made a tight turn. After I shipped Air Carrier X; I watched Air Carrier Y turn and saw that he was turning inside of Air Carrier X. In my estimation; had I turned Air Carrier Y back to the north he would have been in direct conflict and at the same altitude as Air Carrier X creating a dangerous situation. I had no more room to turn Air Carrier Y to the right; so I called traffic and when Air Carrier Y called traffic in sight; I told him to maintain visual separation. At that point; I heard a beep in my ear as if TRACON was calling to coordinate but no one said anything. I figured they heard me calling traffic and getting visual and would help out by turning or climbing Air Carrier X. I let it play out for another couple of miles and when the Air Carrier X didn't turn or climb I restated to Air Carrier Y to maintain visual separation and that Air Carrier X would be paralleling his course for a couple miles. Then I input the heading on the strip and added visual separation so TRACON would know. Noise abatement is probably nice for the people living around the airport; but it ties the hands of the controllers. Because you can't control how tight a pilot will turn; as in this instance; if the first pilot takes an easy turn and the second pilot a tight turn; you are left with no other out other than to maintain visual separation or coordinate a different heading with TRACON.

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.