Date: 201309
Local time of day: 1801-2400
Location: ZZZ.TRACON, US
Aircraft: Navion
Operating under: Part 91
Flight plan: IFR
Flight phase: Cruise
Airspace: Class E ZZZ
ATC / advisory: TRACON ZZZ
Second aircraft: M-20 Series Undifferentiated or Other Model
Reporter organization: Government
Reporter function: Instructor; Approach; Departure
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Workload; Confusion; Situational Awareness
Second reporter function: Departure; Approach
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
Result: General None Reported / Taken
Contributing factors: Human Factors; Procedure
Primary problem: Procedure

Narrative: This event occurred during on-the-job training. It has become common practice in our facility to keep multiple sectors combined due to minimal staffing. In the past; these two subject sectors would be split apart throughout the busy hours of the day because of the unpredictable nature for the two sectors to suddenly increase in both volume and complexity. At any moment this combined sector; can be sequencing arrivals to four satellite airports; feeding arrivals and working the bulk of departures off the primary airport; separating en route aircraft across 70 miles of airspace; and have 13 other sectors calling for coordination. At the time of this event; it was moderately busy and the trainee asked for help but it was already too late to split the sectors. I told her to keep working and the Controller-In-Charge came over to coordinate as it became unmanageable. The loss of separation occurred when the trainee descended a Mooney from 7;000 FT to 5;000 FT while converging with a Navion at 6;000 FT. I did not hear the trainee make the transmission to the Mooney because I was giving instructions to turn other aircraft at the time he/she issued the descent instruction. Traffic volume has been steadily decreasing over the last few years at our facility and it has become a common practice to combine our five operational positions into just two. The motivation behind this has been to increase volume and complexity for the trainee and that the staffing level does not permit us to both train and have more scopes open. Some of the trainees are not proficient or experienced enough to train on combined sectors and it is putting an undue hardship on the instructors to accomplish training. Many of the trainees have no air traffic experience and don't understand the basic fundamentals. Instructors are trying to teach this at the same time as managing unpredictable traffic volume. Management needs to hold regular training team meetings and have skill checks performed by certified personnel to identify weaknesses in the trainee. Training should be tailored to the trainees skill level (i.e. splitting sectors) and skill enhancement training performed where necessary.


Second narrative: This was a training session where I was the CPC-IT. The weather was marginal IFR in most places. I was working 2 scopes combined; without a coordinator. About halfway into the session; traffic became heavy and complex with multiple IFR approaches; military arrivals; IFR-pickups; and frequency congestion from 2 VHF and 2 UHF frequencies. My trainer was also asking me questions about hypothetical scenarios. At this point I asked for help. And I specifically asked for someone to help pull my strips because my strip bay was full and I couldn't get to them fast enough. The CIC came over to help; however he was not pulling my strips down for me and I was unclear as to what coordination he was doing. As the session progressed; I had an aircraft; a Navion; at 060 southwest bound direct to the VOR; which I handed off; transferred communications and turned green on my scope. I also had a Mooney at 070 on my frequency northeast bound that needed to be descended to 050 [per] the LOA. When the Mooney crossed my boundary I immediately descended him to 050; forgetting about the Navion who was passing opposite direction traffic by less than 3 miles. The 2 sectors should have been split from the beginning and possibly a coordinator with each split sector. There was one controller out on break at the time of the incident. It is very common for there not to be enough staffing to support the positions de-combined. The trainer should have held his questions for a less busy time or after debrief as not to rattle the CPC-IT during a complex training session. I should find a way to remember aircraft that are green on my scope but still inside my airspace. Or possibly not turn them green. When the CIC came over to coordinate; he should have also relieved some of the workload by pulling the strips [also] the controller on break should have been called back sooner.


Synopsis: TRACON Controller providing OJT described a loss of separation when traffic increased significantly; positions were combined; and complexity increased.  The reporter noted facility 'combined sectors' for training; as one causal factor.