Narrative:

I was working radar when tower called to coordinate departures. I had a law enforcement VFR aircraft at 3200 feet in the departure corridor; so I instructed the traffic to remain at or above 3000 feet. I approved tower to launch departures at 2500 feet. Aircraft X departed first. I waited until he was past the traffic before climbing and turning him to a 360 heading and capped him at 6000 feet reference traffic at 7000 feet 15 miles north of him. Then second departure took off and went south. I separated the second departure from the traffic and vectored him to intercept a victor airway. I then went back to aircraft X; scanned ahead and did not observe any traffic in his way. I cleared him to 10000 feet. I spoke to multiple aircraft in the meantime; revectored my southbound departure to intercept the victor airway on a better heading; and then turned to the fdio (flight data input/output) to make an amendment. That's when I heard the conflict alarm go off in close proximity to aircraft Y southeast bound at 7500 feet. I observed aircraft X at 7000 feet; then rapidly dropped in altitude to 6600 feet. At that time I instructed aircraft X to maintain 7000 feet just before I observed the altitude change to 6600 feet. Aircraft X then advised me he was taking evasive action.I believe I missed aircraft Y at 7500 feet due to it being obscured by full data block traffic that I was working at the same position of the unidentified limited data block 7500 feet. Maybe if the full data block would auto toggle to a different position even if the other target is a limited data block. I'm 100% sure I scanned ahead prior to sending aircraft X on course and climbed him to 10000 feet; and did not see aircraft Y at the time I made the transmission.

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Original NASA ASRS Text

Title: CAE TRACON Controller reported a loss of separation after climbing an aircraft toward an unnoticed VFR aircraft.

Narrative: I was working Radar when tower called to coordinate departures. I had a law enforcement VFR aircraft at 3200 feet in the departure corridor; so I instructed the traffic to remain at or above 3000 feet. I approved Tower to launch departures at 2500 feet. Aircraft X departed first. I waited until he was past the traffic before climbing and turning him to a 360 heading and capped him at 6000 feet reference traffic at 7000 feet 15 miles north of him. Then second departure took off and went south. I separated the second departure from the traffic and vectored him to intercept a victor airway. I then went back to Aircraft X; scanned ahead and did not observe any traffic in his way. I cleared him to 10000 feet. I spoke to multiple aircraft in the meantime; revectored my southbound departure to intercept the victor airway on a better heading; and then turned to the FDIO (Flight Data Input/Output) to make an amendment. That's when I heard the Conflict Alarm go off in close proximity to Aircraft Y southeast bound at 7500 feet. I observed Aircraft X at 7000 feet; then rapidly dropped in altitude to 6600 feet. At that time I instructed Aircraft X to maintain 7000 feet just before I observed the altitude change to 6600 feet. Aircraft X then advised me he was taking evasive action.I believe I missed Aircraft Y at 7500 feet due to it being obscured by full data block traffic that I was working at the same position of the unidentified limited data block 7500 feet. Maybe if the full data block would auto toggle to a different position even if the other target is a limited data block. I'm 100% sure I scanned ahead prior to sending Aircraft X on course and climbed him to 10000 feet; and did not see Aircraft Y at the time I made the transmission.

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.