Date: 201703
Local time of day: 1201-1800
Location: SCT.TRACON, CA
Flight conditions: VMC
Light: Daylight
Aircraft: Commercial Fixed Wing
Flight plan: IFR
Flight phase: Descent
Airspace: Class E SCT
ATC / advisory: Center ZLA; TRACON SCT
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Communication Breakdown; Distraction; Human-Machine Interface; Situational Awareness; Troubleshooting
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Separated Traffic
Contributing factors: Procedure; Chart Or Publication
Primary problem: Procedure

Narrative: This is linked to a human factors issue with air traffic controllers assuming more responsibility than before. Aircraft are now being managed instead of being controlled; a lot of trust is being placed in a fallible system and by eliminating the 'controller' aspect of descend via's there is likely to be a serious event. Per the LOA ZLA sector 19/20 (specifically) is not allowed to handoff aircraft to the HEMR [Hemet Radar] position with altitude stacks yet they continue to do it; sometimes without an Approval Request (APPREQ). I don't know if this is a safety culture issue or a training deficiency.The DSNEE RNAV arrival from the North and the SIZLR (while procedural separated) can cause the HEMR controller to spend more attention than what should be required to ensure the aircraft will comply with the altitude restrictions which keeps them separated. This extra attention to the North; combined with airspace changes which causes the HEMR position to look at more airspace than before; the controller is more likely to miss a conflict either aircraft to aircraft; or an aircraft transitioning the jump zones in the Southern portion of their airspace. This issue also ties in with the issue mentioned above about leaving aircraft high or stacked from the North and the SIZLR. If an aircraft is high on the DSNEE (which I have seen multiple times) is will be in direct conflict with the SIZLR arrival.Examples provided below:I was relieving a controller from the HEMR position during a period of heavy/complex traffic; ZLA 19 called on the shout line 2-3 times but we were too busy to answer. After I assumed responsibility of the HEMR position a KAYOH arrival and a DSNEE arrival were coming from the North. I took radar on both aircraft and then realized that the [DSNEE arrival] was high on the arrival. [The KAYOH aircraft] was at the appropriate altitude but [the DSNEE aircraft] was left high to overtake and was at FL210 over CARZZ (I shouldn't have taken the handoff). [The DSNEE arrival aircraft] was 2500 feet high at ASPEN.[A 737] was on the DSNEE arrival and [another aircraft] was on the SIZLR arrival; [the 737] looked high at first glance and appeared to be in direct conflict. I used the MIN function and the aircraft were going to be within a mile of each other at crossing points. I called ZLA to ensure [the 737] would meet the crossing restriction prior to taking the handoff (ZLA ensured [the 737] would meet the restriction). Even though each aircraft complied with the crossing restrictions it caused me to place unnecessary attention on the situation which could have resulted in aircraft coming together in the Southern portion of my airspace. Making the crossing restriction at CARZZ 160 instead of at or above 160 should help alleviate this problem.Working with March Approach and getting them to take more airspace in the Southern portion of HEMR (maybe 070 and below) so that HEMR is not tasked to work all the VFR transitions below 070. This would relieve the workload and frequency congestion for the HEMR controller which would allow them to more safely and efficiently work the IFR aircraft on the new Optimization of Airspace Procedures in the Metroplex. If an agreement to give March more airspace can't be reached then HEMR should have the ability to be split. There should be a new position in the EMP area; staffing an assist doesn't always help due to frequency congestion.




Synopsis: SCT TRACON Controller reported new RNAV Arrival procedures are causing increased workload.