Date: 201707
Local time of day: 0601-1200
Location: NCT.TRACON, CA
Flight conditions: VMC
Light: Daylight
Aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class E NCT
ATC / advisory: TRACON NCT
Second aircraft: Any Unknown or Unlisted Aircraft Manufacturer
Reporter organization: Government
Reporter function: Approach
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness; Workload
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Air Traffic Control Separated Traffic; Air Traffic Control Issued New Clearance; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Took Evasive Action
Contributing factors: Procedure; Chart Or Publication; Human Factors; Airspace Structure
Primary problem: Airspace Structure

Narrative: I was working Licke (finals sector for SJC); and an IFR arrival into E16 requesting the visual approach came into my sector from the North. I descended him to 5000 (the lowest I could for the MVAs in the area). I had Aircraft X inbound to SJC descending on the RAZRR arrival; and they were a possible conflict; so I stopped Aircraft X at 6000. As the E16 aircraft approached from the North; I noticed a lot of VFR 1200 codes flying around; possible traffic for my IFR arrival into E16. As I was calling traffic for the E16 arrival; I noticed a target at 5500 feet and called it to him; but I didn't think it would be traffic for my Aircraft X because I didn't realize that this target was relatively fast moving for a 1200 code. I got distracted as the E16 arrival came closer and closer to his airport because he still didn't have the airport in sight when he was about 6 miles away and was still at 5000; which was as low as I could give him on an IFR flight plan in that area. Not only that; but there were multiple other aircraft flying around that I deemed may be traffic for him. He finally decided to cancel IFR and go VFR and over to the advisory frequency; and just at this moment I realized that the 1200 code that was formerly at 5500 was now at 6000 and was rapidly approaching my Aircraft X aircraft head on. I turned Aircraft X as soon as I could and called the traffic; but Aircraft X had already responded to TCAS. It appeared the airplanes came within about a mile of each other; and I didn't lose target resolution; so there was no loss of separation; but it was too close for my comfort and I'm sure for the crew of Aircraft X. I had to significantly vector and stop the descent of the next arrival inbound to SJC to miss a couple of VFR targets (one of them being the same one that just caused the TCAS on Aircraft X). In doing this; it significantly upset the sequence and spacing between the aircraft behind that aircraft; and that third aircraft on final ended up having to do S-turns on the visual approach to land at SJC.This is an issue that we have been dealing with for a long time; but it needs to change. Both of our major arrivals into SJC converge on KLIDE (about a 15 mile final for the airport) and the altitude restriction allows them to descend all the way down to 4000 at KLIDE. There are always tons of VFR aircraft flying around that area passing right over KLIDE and directly into the flight paths of all of our large and heavy jet arrivals into SJC. They SHOULD NOT be allowed to fly there; it is a TERRIBLE spot and this is one of those issues where 'it's just a matter of time.' There's going to be a session soon where someone is extremely busy and there are multiple aircraft not in communication with ATC flying around there; and the controller is going to either not see the traffic (perhaps the traffic is climbing rapidly or changing course and the controller was distracted with other duties) or the sector frequency will be too congested to give instructions to have his IFR arrivals avoid the VFR traffic. This really; REALLY has to be looked at. It is a safety issue. The RNAV arrivals we have into SJC are great arrival procedures; but we need to have some sort of protection against VFR pilots who don't request flight following. Our current procedure is to simply watch out for them and either restrict the altitude of our IFR arrivals (which sometimes leads to an unstable approach or requires additional vectors for descent) or to give the aircraft vectors around the VFR traffic. Having ONE VFR target that we aren't talking to can ruin an entire sequence of IFR arrivals and put a huge burden on both controllers and pilots (in a critical phase of flight no less) on what would normally would have been a smooth; efficient; and very safe operation. This needs to be looked at; and a change needs to be made. Redesigning the Charlie airspace to protect those vulnerable parts of the arrivals would be a very good long term solution.Maybe we can integrate VFR corridors/routings. I realize there is a symbol on VFR charts depicting heavy jet traffic in the area; but it's obviously not working. Something more urgent-looking needs to be on those charts; because we are talking mid-air collision avoidance. In the short term; perhaps some NOTAMS can be sent out. Something needs to be done to educate pilots on where a bad spot is. This is a big issue; and our area has simply got used to working around it. But this needs to change. VFR pilots should not be allowed to fly where they have been flying at those altitudes; it is dangerous.




Synopsis: NCT TRACON Controller reported a conflict with a VFR aircraft and an IFR arrival to SJC in the vicinity of KLIDE.