Regional Jet 200 ER/LR (CRJ200)
Air Traffic Control Fully Certified
Situational Awareness
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance
Procedure; Human Factors
[There was] a BE20 on Visual Approach to the military base; talking to GCA [and] a CRJ2 on Visual Approach to ZZZ talking to Local Control. The CRJ2 appeared to turn base at about 3 miles out; so I was no longer concerned with his separation from the BE20; but then the Conflict Alert (CA) went off; the CRJ2 had extended. I called Local Control; and he said that the CRJ2 was on base leg. I called GCA and told them that the CRJ2 was on base leg. I measured the distance between the 2 aircraft and got 2.68 miles. There were 4 over-flights over ZZZ; so data-tag clutter was an issue; but I should have ensured that the CRJ2 was restricted to a shorter downwind. Recommendation; pay better attention; I should have ensured that the CRJ2 was restricted to a 5-mile final before I switched him.
TRACON Controller described a loss of separation event involving a GCA Approach and a Visual Approach; the separation problem resulting from an extended downwind by the Visual Approach aircraft.