Large Transport; Low Wing; 2 Turbojet Eng
Air Traffic Control Fully Certified
Situational Awareness; Communication Breakdown
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Executed Go Around / Missed Approach
Human Factors; Procedure
Aircraft Y was cleared for the Visual Approach to RWY10 approximately 3.5 miles southwest of SJU and was told to follow another aircraft landing Runway 10. Aircraft X was cleared for the ILS Runway 10 approximately 13 miles west of SJU. Aircraft Y continued on the downwind too long before starting the base turn. Approach called Local and said the current sequence wasn't going to work because Aircraft X was overtaking Aircraft Y who extended the downwind and to send Aircraft Y back to approach for re-sequencing heading 280.Approach issued traffic to Aircraft X and Aircraft X reported the traffic in sight. Aircraft Y made a series of left and right turns into Aircraft X's flight path. Local then told Approach to stop Aircraft X's descent at 2000 feet reference Aircraft Y turning into Aircraft X. Aircraft Y was observed at 1700 feet. Approach issued a traffic alert to Aircraft X about Aircraft Y and stopped Aircraft X at 2000 feet. Aircraft X reported the traffic in sight again and then asked if they could continue on the approach. Approach canceled Aircraft X's altitude restriction once Aircraft Y was southbound and switched Aircraft X to Local. Approach controller was notified shortly after Aircraft X reported an RA. Approach controller relied on Aircraft Y to make a tighter base turn behind following traffic. Instead the controller should have had Aircraft Y follow Aircraft X or slowed Aircraft X sooner or called Aircraft Y base turn to ensure separation.
[Report narrative contained no additional information.]
A Controller reported shipping an aircraft to the Tower assuming it would turn from downwind onto base leg in time to be in front of straight in traffic. The downwind aircraft turned base late and into conflict with the straight in traffic.