Air Traffic Control Fully Certified
Situational Awareness
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance
Human Factors
Both aircraft were on vectors for VOR Runway 23 practice approaches. Aircraft X was turned base (320 heading) and descended from 3;100 FT to 2;100 FT. Aircraft Y was 4 miles in-trail of Aircraft X at 3;100 FT; on the downwind heading (heading 060.) When Aircraft Y was turned onto final (final course heading 240) he was still in the descent to 2;100 FT. Aircraft Y was still on the downwind heading at the same time as Aircraft X was turned final. The separation was lost as the two aircraft passed laterally (final and downwind) due to a tight downwind to final. When I realized that Aircraft Y was going to be too close to Aircraft X for IFR separation; Aircraft Y was turned 'out' to a heading of 070. There were multiple other approaches and IFR student pilot training going on throughout the sector with multiple other aircraft on vectors and/or approaches.
TRACON Controller described a loss of separation event due in part to vectoring traffic for an instrument approach on a tight downwind.