Narrative:

I was working the squib and sparta radar positions combined. The assistant radar position was also staffed. There was aircraft X flying from ord to grr at 13;000 feet. By letter of agreement; sparta descends grr arrivals down to 9;000 feet in the southwest corner of grr approaches airspace; near pmm. Any grr arrival from any other direction is descended to 11;000 feet. I think I then descended aircraft X to 11;000 feet; upon noticing the departure of aircraft Y off biv. I the called the grr controller; to apreq either a lower altitude for aircraft X; 9;000 feet or below; and was going to release 17;000 feet to aircraft Y; so that grr approach could use their air traffic rules and flip-flop the airplanes in altitude. At this point I noticed a departure off of mkg airport climbing southbound. This was noticed during the coordination with grr approach; so I told him I could not release higher for aircraft Y and queried if 9;000 feet was still approved for aircraft X. The controller stated in the affirmative and I told the controller I would call back when I had higher for aircraft Y. I then called the mkg controller and gave instruction for the southbound plane to be cleared to a point further down on his route of flight southwest of where this situation was developing; therefore not becoming a factor. I call grr approach back and released 17;000 feet on aircraft Y with respect to aircraft X; whom I had already transferred communications to grr approach; and the controller read back the 17;000 feet. My traffic and complexity of the sector was increasing and as aircraft Y checked on the frequency leveling at 10;000 feet as grr approach was calling on the shout line and my assistant radar controller was answering. I noticed that aircraft X was descending through 11;500 feet; and due to the fact that aircraft Y was calling on leveling at 10;000feet; I thought the grr controller was telling my assistant radar controller that he had stopped the aircraft X at 11;000 feet and to keep aircraft Y at 10;000 feet until separation was established. The next update was aircraft X descending through 10;600 feet and aircraft Y stated he was responding to an RA. I then climbed aircraft Y up to 17;000 feet. My next clearance to aircraft Y was to clear him direct lan. Recommendation; if all the grr arrivals went to 11;000 feet instead of 9;000 feet; this problem would have never occurred; especially due to the close proximity of biv airport and mkg approach. Biv departures should not be climbed to 10;000 feet without coordination with grr approach when there are grr arrivals from the southwest. This solution would as well alleviate this potentially extremely hazardous situation. Mkg approach or grr approach should take control of the airspace up to 10;000 feet in the shelf of airspace around the pmm VOR. This too; would solve this situation.

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Original NASA ASRS Text

Title: ZAU controller experienced a loss of separation event when coordination with GRR and was confused and arrival and departure traffic from MKG conflicted.

Narrative: I was working the Squib and Sparta RADAR positions combined. The Assistant RADAR position was also staffed. There was Aircraft X flying from ORD to GRR at 13;000 feet. By Letter Of Agreement; Sparta descends GRR arrivals down to 9;000 feet in the Southwest corner of GRR approaches airspace; near PMM. Any GRR arrival from any other direction is descended to 11;000 feet. I think I then descended Aircraft X to 11;000 feet; upon noticing the departure of Aircraft Y off BIV. I the called the GRR controller; to APREQ either a lower altitude for Aircraft X; 9;000 feet or below; and was going to release 17;000 feet to Aircraft Y; so that GRR approach could use their air traffic rules and flip-flop the airplanes in altitude. At this point I noticed a departure off of MKG airport climbing Southbound. This was noticed during the coordination with GRR approach; so I told him I could not release higher for Aircraft Y and queried if 9;000 feet was still approved for Aircraft X. The controller stated in the affirmative and I told the controller I would call back when I had higher for Aircraft Y. I then called the MKG controller and gave instruction for the Southbound plane to be cleared to a point further down on his route of flight Southwest of where this situation was developing; therefore not becoming a factor. I call GRR approach back and released 17;000 feet on Aircraft Y with respect to Aircraft X; whom I had already transferred communications to GRR approach; and the controller read back the 17;000 feet. My traffic and complexity of the sector was increasing and as Aircraft Y checked on the frequency leveling at 10;000 feet as GRR approach was calling on the shout line and my Assistant RADAR controller was answering. I noticed that Aircraft X was descending through 11;500 feet; and due to the fact that Aircraft Y was calling on leveling at 10;000feet; I thought the GRR controller was telling my Assistant RADAR controller that he had stopped the Aircraft X at 11;000 feet and to keep Aircraft Y at 10;000 feet until separation was established. The next update was Aircraft X descending through 10;600 feet and Aircraft Y stated he was responding to an RA. I then climbed Aircraft Y up to 17;000 feet. My next clearance to Aircraft Y was to clear him direct LAN. Recommendation; If all the GRR arrivals went to 11;000 feet instead of 9;000 feet; this problem would have never occurred; especially due to the close proximity of BIV airport and MKG approach. BIV departures should not be climbed to 10;000 feet without coordination with GRR approach when there are GRR arrivals from the Southwest. This solution would as well alleviate this potentially extremely hazardous situation. MKG approach or GRR approach should take control of the airspace up to 10;000 feet in the shelf of airspace around the PMM VOR. This too; would solve this situation.

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.