Date: 201405
Local time of day: 1201-1800
Location: OKC.TRACON, OK
Light: Daylight
Aircraft: Large Transport
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class E OKC
ATC / advisory: TRACON OKC
Second aircraft: Small Aircraft
Reporter organization: Government
Reporter function: Approach
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Distraction; Confusion
Second reporter function: Instructor; Approach
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Air Traffic Control Separated Traffic
Contributing factors: Procedure; Company Policy; Human Factors
Primary problem: Procedure

Narrative: Aircraft X descending on radar vector OKC RWY35R from DECKK from 15;000 feet to 7;000 feet. My co-worker was working this aircraft in my airspace with approval. I had just had a VFR come into conflict with my IFR arrival and the Supervisor suggested that I allow my co-worker to work this second arrival into OKC to alleviate workload. We stopped Aircraft X at 7;000 feet to avoid an unidentified VFR aircraft maneuvering at the time around 5;000 - 6;500 feet. My co-worker vectored Aircraft X to the west of the unknown aircraft and issued traffic. Aircraft X reported aircraft in sight and was told to maintain visual separation; descend and maintain 4;000 feet. Aircraft X reported traffic no factor and continued his descent. The unknown aircraft then reversed course and became in direct conflict with Aircraft X. Aircraft X abruptly began to climb in accordance with a TCAS/RA. The unknown aircraft began a steep and fast descent at approximately the same time. Separation was regained and Aircraft X landed at OKC without further incident. A third co-worker watched the unknown target become identified by OUN Tower. We never had any contact with this unknown aircraft.Inform the flight school of the danger of maneuvering in this area when multiple aircraft are inbound to OKC final and OKC Satellite airports. This is a constant problem with Airlines and other GA aircraft performing TCAS/RA maneuvers or being vectored away from VFR practice area aircraft causing delays to air traffic. Suggest to the flight school to either call for flight following; fly at a lower altitude or maneuver elsewhere. This is not illegal but highly dangerous. This happened three times today.


Second narrative: I was the OJTI working the airspace adjacent to the occurrence. My trainee transferred Aircraft Z to the NW/SW/FR CPC on vectors to PWA RWY35R level 6;000 feet in accordance with the 'flow.' I had seen an unknown aircraft maneuvering at 5;500 feet south east of IRW on the IRW160R [at] approximately 20 miles. I brought this to the attention of the NW/SW/FR controller since we had an incident where an unknown aircraft about two hours earlier had come into conflict with two different airliners in two separate incidents. My co-worker acknowledged traffic and was currently observing and tracking the target. As Aircraft Z came closer to the unknown aircraft; the unknown traffic began to climb and level at 6;000 feet. My co-worker issued traffic and I believe a safety alert. Aircraft Z reported aircraft in sight. Due to the abrupt nature of the unknown aircrafts flight path and altitude my co-worker could not suggest whether to descend or turn. He told Aircraft Z that he was able to maneuver left/right or climb/descend to avoid traffic. Aircraft Z decided to descend immediately to 4;000 feet. Later; I watched the unknown target become identified by OUN Tower. We never had any contact with this unknown aircraft. This aircraft is suspected in two other close proximity events today and ATSAP reports were filed on both events.


Synopsis: OKC Approach Controller reports about two different events involving flight school aircraft that gets in the way of arrival traffic to primary airport causing RA.