Narrative:

I was working final. I had a VFR aircraft inbound for on a wide base; and some aircraft that called apn off 5c1 for flight following. I had issued the outbound VFR traffic to the inbound VFR traffic. I had descended aircraft X to 5000 ft and issued traffic to him. It was then I noticed the outbound traffic climbing fast. I then stopped aircraft X at 6000 ft and had to issue a traffic alert with a right turn. The pilot [of aircraft X] said the VFR plane came within 100 feet of him. The apn controller told me he had issued the VFR plane off 5c1 to maintain VFR at or below 3500 and to contact me. He never called me and didn't acknowledge with a shout in the blind prior to the traffic alert. This happens frequently. 5c1 tends to be a busy airport that just happens to be on san antonio's final. Planes out of there often do not use caution and expect us to see them and avoid them. Without talking to them we do not know what they plan to do. In this case; the plane did try to call approach. However; the plane chose to not follow instructions. We need pilots that depart and land 5c1 to be more aware of the dangers of its proximity to san antonio and be willing to work with controllers. This is a safety issue that can't be ignored and requires cooperation in part of controllers and pilots. I am not as experienced here at san antonio; so I don't have an airspace or procedures suggestion at this time.

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Original NASA ASRS Text

Title: Air Traffic Controller reported a VFR aircraft did not comply with instructions resulting in a NMAC.

Narrative: I was working final. I had a VFR aircraft inbound for on a wide base; and some aircraft that called APN off 5C1 for flight following. I had issued the outbound VFR traffic to the inbound VFR traffic. I had descended Aircraft X to 5000 ft and issued traffic to him. It was then I noticed the outbound traffic climbing fast. I then stopped Aircraft X at 6000 ft and had to issue a traffic alert with a right turn. The pilot [of Aircraft X] said the VFR plane came within 100 feet of him. The APN controller told me he had issued the VFR plane off 5C1 to maintain VFR at or below 3500 and to contact me. He never called me and didn't acknowledge with a shout in the blind prior to the traffic alert. This happens frequently. 5C1 tends to be a busy airport that just happens to be on San Antonio's final. Planes out of there often do not use caution and expect us to see them and avoid them. Without talking to them we do not know what they plan to do. In this case; the plane did try to call Approach. However; the plane chose to not follow instructions. We need pilots that depart and land 5C1 to be more aware of the dangers of its proximity to San Antonio and be willing to work with controllers. This is a safety issue that can't be ignored and requires cooperation in part of controllers and pilots. I am not as experienced here at San Antonio; so I don't have an airspace or procedures suggestion at this time.

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.