Small Transport; Low Wing; 2 Recip Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 2
Situational Awareness
ATC Issue All Types; Conflict NMAC; Deviation / Discrepancy - Procedural Other / Unknown
Air Traffic Control Issued Advisory / Alert
Company Policy; Human Factors; Procedure
Aircraft X requested VFR flight following for a short flight from at 1;000 feet. The pilot had opposite direction VFR traffic indicating 800 feet. I issued the traffic at 8 miles. Aircraft X did not have the traffic in sight. The VFR aircraft indicated level at 800 feet so at 5 miles I reissued the traffic and suggested a VFR climb if not in sight. Aircraft X did not have the traffic in sight and executed a climb to 1;500 feet. At 3 miles; I reissued the traffic and advised the pilot that the targets appeared likely to merge. The pilot did not request a vector for the traffic. Aircraft X then reported the traffic in sight at his same altitude of 1;500 feet; and not at the indicated 800 feet. During the time both before and after the conflict; the VFR traffic showed single sweep altitude changes to altitudes of 1;200; 1;600; and 1;700 feet; very infrequently.I should have issued proactive vectors to de-conflict the traffic situation since both altitudes were not verified.
K90 TRACON Controller reported an unidentified VFR aircraft was a NMAC with a VFR aircraft the Controller was working.