Narrative:

While on a west flow with combined sectors the radar controller was training and had a trainer watching the situation unfold. The radar controller shortcut many inbound O'hare arrivals direct hulls that were coming from the south and from the south east. Normally this isn't a factor with the midway arrivals. In this particular situation the radar controller had short cut the O'hare stream which left the O'hare arrival under the midway arrivals. When doing this the midway arrivals were issued a crossing of cross meggz at 11;000 feet.the problem with doing this is that the midway arrivals cross meggz at 11;000 feet and hulls at 12;000 feet. This causes the midway arrivals to pass through the O'hare arrivals altitude; essentially having the O'hare traffic cut off the midway traffic. This occurred and a loss of separation occurred as I was on the radar assist. While this was happening the radar trainee asked the instructor if they should turn the O'hare arrival left to avoid the separation loss. The trainer said the midway will be at 11;000 feet shortly. The loss of separation then occurred within one or two updates.I would have either not gave the O'hare arrival direct hulls and used another point on the arrival in order to be conscious of the midway stream so I don't have one stream cut the other stream off; or I would have turned the O'hare arrival left/west until the midway arrival was at 11;000 feet.

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Original NASA ASRS Text

Title: A Center Radar Trainee gave a shortcut to an arriving aircraft which placed it into conflict with another arriving aircraft.

Narrative: While on a west flow with combined sectors the radar controller was training and had a trainer watching the situation unfold. The Radar controller shortcut many inbound O'hare arrivals direct HULLS that were coming from the south and from the south east. Normally this isn't a factor with the Midway arrivals. In this particular situation the Radar Controller had short cut the O'hare stream which left the O'hare arrival under the Midway arrivals. When doing this the Midway arrivals were issued a crossing of cross MEGGZ at 11;000 feet.The problem with doing this is that the Midway arrivals cross Meggz at 11;000 feet and HULLS at 12;000 feet. This causes the Midway arrivals to pass through the O'hare arrivals altitude; essentially having the O'hare traffic cut off the Midway traffic. This occurred and a loss of separation occurred as I was on the Radar Assist. While this was happening the Radar trainee asked the instructor if they should turn the O'hare arrival left to avoid the separation loss. The trainer said the Midway will be at 11;000 feet shortly. The loss of separation then occurred within one or two updates.I would have either not gave the O'hare arrival direct Hulls and used another point on the arrival in order to be conscious of the Midway stream so I don't have one stream cut the other stream off; or I would have turned the O'hare arrival left/west until the Midway arrival was at 11;000 feet.

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.