Commercial Fixed Wing
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 2.75
Conflict NMAC
Flight Crew Requested ATC Assistance / Clarification
Aircraft; Airspace Structure; Human Factors
I was working West Radar with all sectors combined to me. I descended Aircraft X to 6;000 MSL when he crossed into my airspace and told him to expect Runway XXL. Visual approaches were being advertised on the ATIS. I pointed out the field to him either abeam the field or just prior to that point and he called the runway in sight. I cleared him for the visual approach and shipped him to tower while he was on a north downwind. I did not observe any traffic for him along his route of flight. I was vectoring another aircraft for the visual approach to Runway XXR when Tower called down and said that Aircraft X reported an aircraft about 200 feet above him. I then looked and saw a primary target southeast bound that I was not talking to; nor had I seen him prior to shipping him. I called out to the supervisor that Aircraft X had an aircraft about 200 feet above him that I wasn't talking to. I continued to work my traffic and tracked the primary target until I got relieved from position about 5 minutes later.
Aircraft X contacted Tower in a wide right downwind; cleared for visual approach RWY XXL at ZZZ. I was working local control and cleared Aircraft X to land RWY XXL. After turning about a 12 mile right base; Aircraft X reported Aircraft Y a couple hundred feet above him a mile back. I informed Aircraft X that i was only showing a faint primary target a couple miles behind him; which usually indicates low level traffic or 'ghost' targets; and asked him to verify that the traffic was above him. Aircraft X confirmed that Aircraft Y traffic was a couple hundred feet above him; which would have been approximately 5;500 Feet MSL. I informed Approach Control of the traffic maneuvering above and outside of the Class C airspace and the CIC (Controller in Command) called the OS/FLM (Front Line Manager) to inform him of the situation.Upgrade ZZZ Class C airspace to increase the lateral limits; allowing us to accommodate airlines to extended final patterns and requiring VFR aircraft to have ADS-B and be talking to ATC within 12 miles at 5;500 Feet MSL.
TRACON and Tower Controller reported they were made aware by a pilot that an aircraft had flown above them while on descent causing an NMAC.