Narrative:

I was working combined radar approach control from the east side R3 position. Aircraft X was descending west to east on an IFR flight plan to ues. I received aircraft X from ZAU descending to 110 and continued his decent to 050 to comply with mke LOA. I received aircraft Y from mke approach ripon sector north east of unu airport level at 060 enroute to sus. Somewhere between unu and ryv I inadvertently terminated control on aircraft Y resulting in a dropped data block. The target still showed a splat with altitude. As I was scanning aircraft X's descent to see if he was going to make his descent per our LOA to 050 before entering mke airspace. I saw the 060 altitude splat over ryv without a data tag and assumed it was a VFR aircraft. I issued traffic to aircraft X told him to stop descent. Aircraft X leveled at 063. I then realized that this was not a VFR aircraft but aircraft Y enroute to sus. Before I issued traffic to aircraft Y he reported aircraft in sight as the ca alert chimed. Aircraft Y passed behind aircraft X at an estimated 2 miles and 300 feet vertical. The event happened due to my inadvertent dropping of the IFR tag enroute to sus; and failing to realize that the tag was an aircraft I had on frequency and was IFR. My scan missed the dropped data block.to prevent this from happening I need to pay particular attention to tags I drop. I also need to slow my scan to ensure I am aware of all targets on my scope.

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Original NASA ASRS Text

Title: MSN Controller drops IFR tag not realizing it and later has conflict with other IFR aircraft causing a loss of separation.

Narrative: I was working combined Radar Approach Control from the east side R3 position. Aircraft X was descending west to east on an IFR flight plan to UES. I received Aircraft X from ZAU descending to 110 and continued his decent to 050 to comply with MKE LOA. I received Aircraft Y from MKE Approach Ripon sector north east of UNU airport level at 060 enroute to SUS. Somewhere between UNU and RYV I inadvertently terminated control on Aircraft Y resulting in a dropped data block. The target still showed a splat with altitude. As I was scanning Aircraft X's descent to see if he was going to make his descent per our LOA to 050 before entering MKE airspace. I saw the 060 altitude splat over RYV without a data tag and assumed it was a VFR aircraft. I issued traffic to Aircraft X told him to stop descent. Aircraft X leveled at 063. I then realized that this was not a VFR aircraft but Aircraft Y enroute to SUS. Before I issued traffic to Aircraft Y he reported aircraft in sight as the CA alert chimed. Aircraft Y passed behind Aircraft X at an estimated 2 miles and 300 feet vertical. The event happened due to my inadvertent dropping of the IFR tag enroute to SUS; and failing to realize that the tag was an aircraft I had on frequency and was IFR. My scan missed the dropped data block.To prevent this from happening I need to pay particular attention to tags I drop. I also need to slow my scan to ensure I am aware of all targets on my scope.

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.