Large Transport; Low Wing; 2 Turbojet Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 5
Confusion; Distraction; Situational Awareness
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Provided Assistance; Flight Crew Returned To Clearance
Human Factors; Procedure; Equipment / Tooling
I had just assumed the radar position in which prior training had occurred.  As a result of this training I believe the some aircraft were out of an efficient/good position for the approach sequence.  I attempted to fix this situation which contributed to complexity.  I was working multiple sectors/frequency in which frequency congestion was apparent with aircraft stepping on one another.  Aircraft Y; VFR requested a practice approach.  I advised the aircraft to expect vectors for the sequence as he was going to be delayed slightly due to other inbound traffic.  I assigned Aircraft Y a vector west for the final and restricted his altitude at or below 2;500.  The aircraft was level and 2;500 and never deviated from that altitude.  Inbound from the west was Aircraft X; IFR. Aircraft X was issued a heading to parallel final due to slower aircraft on the approach; and was issued a decent to 3;000 from 5;000.  Aircraft X leveled at 3;000 for a few miles and I issued a turn for a box pattern to base.  Aircraft X level at 3;000 and Aircraft Y level and restricted at or below 2;500 appeared to be converging and traffic was issued to Aircraft X.  At approximately 1 mile apart Aircraft X started descending and advised they were responding to an RA.  This response to the RA caused a Lack Of Separation Standards (LOSS) and created a real collision hazard. There was no other traffic in the immediate area.It is my understanding that certain company policies require pilot action with regards to a TCAS RAs however in this instance it caused a potential collision that was otherwise a controlled and safe operation.  A review of airline TCAS policies and or software upgrade to TCAS systems may prevent this hazard in the future.
A PVD TRACON Controller reported of a loss of separation when an IFR aircraft reacting to an RA descends into the altitude structure of a VFR aircraft. The Controller would like a review of airline TCAS policies and/or a software update to the TCAS System.