Air Traffic Control Fully Certified
Confusion; Situational Awareness; Training / Qualification
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance
Human Factors
I was the OJTI providing training to a Developmental on all RADAR positions combined.  We were working approximately 8-10 aircraft at the time of the event.  The Developmental was getting behind and I was trying to help the Developmental work through the issues and catch up without having to take the position.  Aircraft X was being vectored for a Visual Approach and descending for the airport.  Aircraft Y had just called up for VFR flight following and been identified at 6;500 feet.  Aircraft X was cleared down to 5;000 feet and had received several vectors around overflight traffic.  The final vector that aircraft X was given prior to the event; was a heading of 220 from the northeast to be set up on a right base for Runway XX.  I told the Developmental to instruct aircraft X to turn right heading 240; descend to 4;000 feet; and issue traffic on aircraft Y because the 2 aircraft were in conflict with each other.  Aircraft X was issued traffic on aircraft Y; reported aircraft Y in sight; told to maintain visual separation; but did not respond that they would comply; then alerted that they were responding to an RA.  I did not take over the position until aircraft X said they had the traffic in sight.  I believe that this event happened because I allowed the Developmental to go too far without taking the position.  I allowed myself to be distracted by helping the Developmental with lower priorities.  At the time that I realized aircraft X and aircraft Y were in an unsafe situation; my resolution was too little too late.  I had told the Developmental what to do instead of just taking over the position and doing what I believed needed to be done.  I have trained the Developmental for the past year and was comfortable with knowing what their abilities were and were not.  I became complacent as the session dragged on.  I would recommend that at no time should this position be in the TRACON alone and without assistance.  If training is being conducted; there should be an assist or flight data controller signed on position and working in the TRACON. Also; when training; sessions should be kept to; 1 hour or as close to 1 hour; as possible to prevent OJTI fatigue.  Being the OJTI for 1hour and 30 minuets is much more difficult and challenging than just working the position by yourself.
This event took place during my training session.  I had aircraft X from the northeast heading southwest bound descending from 11;000 feet to 5;000 feet.  I had a few overflights in the airspace; one that was a VFR aircraft Y flying from the southeast heading northwest bound at a heading of 065.  The instructions given to aircraft X to descend to 5;000 feet was in order to get the plane below the overflight; and then turn inbound to our airport.  After watching the rate of descent; I mentioned that I would issue a 'paper stop' and instruct aircraft X to maintain 7;000 feet until passed the traffic; my instructor then had me issue a turn and further the descent away from aircraft Y; I issued the turn and descent and issued traffic so the aircraft X pilot will be able to look for the VFR aircraft Y.  Seconds later; aircraft X said he was responding to an RA.  My instructor took over the frequency to have the aircraft X pilot advise when he was able to accept further instructions.  The pilot informed us he was able to; so I continued to turn him inbound and descend to ZZZ for the Visual Approach.  During my training session; we had a Supervisor at the facility and marked on as the CIC-2; however he was not in the TRACON during the event; this has been quite popular; supervisors will be 'CIC-2' yet not be in the TRACON.  About 5-10 minutes after the RA; I gave the position to the Supervisor.  After I monitored the position for the required time; I attempted to discuss the training session with my OJTI; yet was instructed to go up to the tower and get on Local Control.  After a training session of one hour and thirty minutes; I was working Local Control for 47 minutes; with no OJT briefing and no discussion about the RA that had just occurred.  I feel that it was simply communication between my instructor and I during the quick discussion about aircraft X getting a 'paper stop' or not.  However; the fact that the Supervisor was marked as our CIC-2; and not in the TRACON to observe the situation; could have been avoided by enforcing the title of CIC-2; and have them remain in the operation.
TRACON Controller providing OJT described a conflict event when failing to take over the position in a timely manner.