Date: 201705
Local time of day: 0601-1200
Location: SCT.TRACON, CA
Light: Daylight
Aircraft: Small Aircraft; Low Wing; 1 Eng; Retractable Gear
Operator: Air Taxi
Operating under: Part 135
Flight plan: VFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class E SCT
ATC / advisory: TRACON SCT
Second aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Reporter organization: Government
Reporter function: Approach
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Human-Machine Interface; Workload; Time Pressure; Situational Awareness; Distraction; Confusion; Communication Breakdown
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic
Contributing factors: Airspace Structure; Human Factors; Procedure
Primary problem: Procedure

Narrative: This report describes a significant confliction between the Metroplex designed ANJLL RNAV arrival into LAX and VFR aircraft on V137. I was working the EAFR (East Feeder Radar) sector at SCT. EAFR is a sector in the LAX arrival area at Southern California TRACON. It acts as the primary feeder sector for LAX arrivals from the east. The purpose of the sector is to accept LAX arrival handoffs from ZLA 20 and to organize the flow before it is given to the final approach sectors. EAFR sector accepts LAX arrival handoffs from ZLA 20. These aircraft are given 'descend via' clearances on the Metroplex designed ANJLL 1 RNAV arrival by ZLA prior to the frequency change to the EAFR sector. Aircraft Y was given a descend via clearance on the ANJLL by ZLA. As the EAFR; I accepted the handoff knowing this. There is a crossing restriction on the ANJLL STAR at CAANN fix at or above 17000 ft. Aircraft X was conflicting VFR traffic eastbound on V137 at 17500 ft. I observed this traffic and stopped Aircraft Y at FL190. There was no loss of separation; closest proximity was 0.3 miles and 1500 ft. Aircraft X appeared to have been handed off to the Hemet sector; which is in another area at SCT. This happened in ZLA airspace close to the EAFR boundary. Had I not stopped Aircraft Y's descent; it is possible he could have been at the same altitude as Aircraft X with less than half a mile of lateral separation. This is the second time that I have had to stop aircraft on the ANJLL star above conflicting VFR traffic at 17500 in ZLA airspace. Informally; other Controllers in the LAX arrival area have run into this issue. The Metroplex representatives know; but the response has been lackluster. What is worrisome is that all players involved; i.e. the pilots; the ZLA controller; and the Hemet controller; might have the best of intentions and not realize a procedural confliction exists. Hemet may assume the ZLA waited until all confliction were resolved before transferring communications. The VFR pilot might assume radar services provided by controllers alleviate any significant confliction. The ZLA controller may assume Hemet will issue a VFR descent. But none of these things are happening. Because there is the potential for a significant loss of separation; and because this appears to happen several times a week; and because the channels to report this safety issue are muddled; I believe significant action is warranted. At minimum; there should be a review of the procedures at SCT and ZLA the ensure separation between VFR traffic on V137 and aircraft descending via the ANJLL star. It may make sense for ZLA 20 to stop issuing 'descend via' clearances and to stop all ANJLL arrivals at FL190 until it is determined why some VFR aircraft intersect the STAR at 17500.

Callback: Reporter stated there seems to be a problem with everyone thinking someone else is taking care of the problem.  When talking to a controller at ZLA; the reporter stated that the ZLA Controller said; 'It's just a VFR.'



Synopsis: SCT TRACON Controller reported conflict problems with aircraft descending via the ANJLL 1 STAR into LAX and VFR traffic on V137 airway.