Date: 201503
Local time of day: 1201-1800
Location: SCT.TRACON, CA
Light: Dusk
Aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class E SCT; Special Use PSP TRSA
ATC / advisory: TRACON SCT
Second aircraft: Small Aircraft
Reporter organization: Government
Reporter function: Approach; Instructor
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness
Second reporter function: Trainee; Approach
Anomaly: ATC Issue All Types; Conflict NMAC
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Took Evasive Action
Contributing factors: Procedure; Human Factors; Airspace Structure
Primary problem: Airspace Structure

Narrative: I was working as an OJTI to my trainee on the Desert sector. Traffic had been busy all day and mostly complex; definitely a busy day. Runway 13 was in use at the airport and visual approaches were being utilized. Aircraft X was an IFR on a left downwind for PSP. My trainee cleared Aircraft X for a visual approach to runway 13R like normal. Aircraft X turned base approx. 8 miles NE of the airport and was descending. Multiple other things were going on around the airspace forcing both the trainee and I to keep our scans going all around the airspace. My trainee picked up a target exiting the Banning Pass (mountain pass approx. 15 miles west of PSP) low level (I believe at 4;000 feet in a slow descent) and issued traffic to Aircraft X.  Aircraft X acknowledged the traffic. Only a few seconds went by before I stepped in and issued a traffic alert to Aircraft X and told them to maintain 4;000 feet. At the time I issued the traffic alert; the radar showed Aircraft X at 4;100 feet and the unidentified target at 3;500 feet. Aircraft X responded 'We're already through 4;000 feet '. I don't remember the exact time that Aircraft Y called us for advisories; but he said where he was and his altitude; and I immediately knew that the target was him. Aircraft X said 'We're descending'. I believe I said 'Aircraft Y on frequency descend to 2;500 feet immediately; do you have the aircraft at 11 o'clock and a half mile in sight?' I received no response; but I observed the target descending rapidly. I received no word from Aircraft X on if they were responding to an RA; which is why I continued to try and resolve the situation. At this time; both aircraft were in rapid descents to try and avoid each other; one listening to my recommendation; and the other not. I found out later that Aircraft X had responded to three RAs; but did not advise me; which to me is understandable given the altitude and the proximity. I observed both targets merge; one showed 2;200 and one showed 2;300.Aircraft X finally came back and said 'OK; we got him now; he's right over the top of us'. The pilot for Aircraft X said they would like to be re-sequenced for an approach in which I complied. I took over for the trainee until Aircraft X was switched to the tower. Radar coverage in the Banning Pass is non-existent below 6;000 feet. We can pick up aircraft around the pass if they are at 5;500 to 5;000 feet; but they usually are intermittent hits. At 4;500 feet and below; our radar will only pick them up once they are at the intersection of Interstate 10 and Highway 111. This intersection is absolutely in the arrival corridor for PSP when they are landing 13R. It's also right in the departure corridor for 31L. This is about here we picked up Aircraft Y on radar. However; when we are working other aircraft; our scan cannot be on one spot 100% of the time.  The trainee picked up the target in time to issue traffic; but his lack of experience led to him not giving a traffic alert right away; which is why I stepped in. Aircraft Y did not call us for advisories when in the pass; where we could have given him instructions to remain clear of the arrival corridor; and by the time he called; the scenario was already happening.  There is no requirement for Aircraft Y to call. Aircraft Y was more than legal being where he was; even though he was in the TRSA; participation is entirely optional on the part of the pilot. PSP is a slow airport in the summer time; but a very busy airport; not just for IFR's; in the winter. My recommendation is to create a Class C airspace around the PSP airport that would protect these aircraft from VFR pilots transitioning through their area. Protect the arrival and departure corridors for these aircraft who do not have much room to maneuver due to terrain. The TRSA around the airport does absolutely nothing to promote safety and protect the aircraft trying to take off and land at PSP. This may be my first report on the issue; butit is definitely not the first time a target has appeared from Banning and converged with an aircraft attempting to land at PSP. I'm not sure how many other reports have been filed for this problem; but it is absolutely a dangerous situation.


Second narrative: I was training on Desert Radar when I cleared Aircraft X for a visual approach to runway 13R at PSP. There was an unidentified VFR aircraft that popped up at 3;500 feet coming out of the Banning pass northwest of PSP. There is no radar coverage for aircraft in the Banning pass below about 5;000 feet. I issued traffic to Aircraft X. When Aircraft X was about 2 miles from the traffic my instructor keyed up and told Aircraft X to maintain 4;000. Aircraft X advised that they were currently descending through 4;000. That is when Aircraft Y called up for flight following. My instructor told Aircraft Y to descend immediately. Aircraft X kept descending responding to an RA. Both targets were indicating about 2;500 feet when the targets merged. Aircraft X reported seeing Aircraft Y in a steep climb to just make it over their aircraft. Aircraft X then said they would need to abandon the approach and was vectored back around for another approach.There is currently a TRSA over PSP. Aircraft Y was skirting around the 4 mile Class D that surrounds PSP before eventually calling ATC because they saw Aircraft X heading right at them. There needs to be a Class C at PSP. The TRSA is useless for protecting aircraft departing and arriving to PSP. Aircraft are not currently required to call ATC for transition through the TRSA. It is only a matter of time before one of these VFR aircraft hit an airliner arriving or departing PSP. The area surrounding PSP during the winter months has a very heavy volume of VFR aircraft. Most of the VFR aircraft do not call for flight following leading to dangerous situations regularly for the IFR aircraft in the vicinity of PSP airport. There are only a few TRSA's left in the country; I feel that is because everyone has realized how useless they are at keeping departing and arriving airliners safe from VFR aircraft not talking to ATC.


Synopsis: Four reports from an SCT Controller providing training; his trainee Controller and the crew of an airline aircraft documenting a near mid-air caused by an aircraft coming out of the Banning Pass and conflicting with the airliner turning final for PSP.