Sat TRACON controller reported of an unsafe issue when an aircraft on a visual approach was followin...

Narrative:

I was working apw [approach west] which is the final position for sat on a runway 13R/left flow. The weather was unrestricted VFR. I told aircraft X to follow an aircraft and cleared him for the visual approach. Aircraft X extended his base to a point that was taking him over 5c1. In the vicinity of 5c1 were multiple primary and secondary radar targets. As his separation increased to approximately 9 miles I inquired if he still had the aircraft in sight. At that moment; one of the primary aircraft's transponder turned on. The target was about 1 mile from aircraft X indicated 4500 feet converging rapidly. I immediately told aircraft X to turn right heading 090 immediately and issued the traffic alert. Aircraft X did not respond; but appeared to be turning and climbing. He later advised me he was responding to his TCAS advisory.there are a few things that could be done. We currently work in class C airspace; but due to the amount of departures we have we are not allowed to be a class B. I think if there were a waiver for this and we could be class B; we could more effectively control the traffic in and around this airport. Another option would be extending the class C so that at the very least they would have to be talking to us in order to climb that high and we could control them better from that perspective. The one thing I do know and I am not saying this lightly; if we do nothing it is not a matter of if a mishap will occur; it is a matter of when. 100%; if this problem is not addressed there will be a catastrophic breakdown in the safety of air traffic.

Original NASA ASRS Text

Title: SAT TRACON Controller reported of an unsafe issue when an aircraft on a visual approach was following traffic and became extended over another airport; and traffic around that airport.

Narrative: I was working APW [Approach West] which is the final position for SAT on a RWY 13R/L flow. The weather was unrestricted VFR. I told Aircraft X to follow an aircraft and cleared him for the visual approach. Aircraft X extended his base to a point that was taking him over 5C1. In the vicinity of 5C1 were multiple primary and secondary radar targets. As his separation increased to approximately 9 miles I inquired if he still had the aircraft in sight. At that moment; one of the primary aircraft's transponder turned on. The target was about 1 mile from Aircraft X indicated 4500 feet converging rapidly. I immediately told Aircraft X to turn right heading 090 immediately and issued the traffic alert. Aircraft X did not respond; but appeared to be turning and climbing. He later advised me he was responding to his TCAS advisory.There are a few things that could be done. We currently work in Class C airspace; but due to the amount of departures we have we are not allowed to be a Class B. I think if there were a waiver for this and we could be Class B; we could more effectively control the traffic in and around this airport. Another option would be extending the Class C so that at the very least they would have to be talking to us in order to climb that high and we could control them better from that perspective. The one thing I do know and I am not saying this lightly; if we do nothing it is not a matter of if a mishap will occur; it is a matter of when. 100%; if this problem is not addressed there will be a catastrophic breakdown in the safety of air traffic.

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.

Attributes
ACN	1445897
Time
Date	201705
Local Time Of Day	1801-2400
Place
Locale Reference	SAT.Airport
State Reference	TX
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Medium Transport
Flight Phase	Final Approach
Route In Use	Visual Approach
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	Climb
Route In Use	None
Person 1
Function	Approach
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (mon) 10
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types

Sat TRACON controller reported of an unsafe issue when an aircraft on a visual approach was following traffic and became extended over another airport; and traffic around that airport.