Date: 201811
Local time of day: 1801-2400
Location: NCT.TRACON, CA
Aircraft: Citation II S2/Bravo (C550)
Flight plan: IFR
Flight phase: Final Approach
Airspace: Class B SFO
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: Conflict Airborne Conflict
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Air Traffic Control Separated Traffic
Contributing factors: Airspace Structure; Human Factors
Primary problem: Airspace Structure

Narrative: I was working Mulford/Grove combined during [a busy period]. Weather extremely VMC and all the travelers returning; everyone was out flying and it was ridiculously busy. For nearly 2 hours; I was overloaded with no assistance for the first hour. Short staffing and Supervisor lack of awareness contributed to not receiving any help. VFR aircraft not talking to anyone were flying and doing air work at altitudes they had no business being at - but are now allowed to because the Bravo altitudes were raised so high; without any corresponding Charlie airspace changes to protect our traffic into Oakland. I was using what I felt were overly safe altitudes to separate arriving IFR traffic from the mess of VFR traffic in the way; but even my 'overly safe' precautions weren't enough: I told Aircraft X (call sign estimated - the last three digits are correct though) to track the approach course inbound but maintain 4;500 [feet] for a target that was below 3;500 [feet]. It was too high for Aircraft X to make a stabilized approach; but I had to keep him safe and vectors weren't going to help the situation. I tended to other conflicts for the other runway; and when I looked back the Collision Alert went off as the VFR target climbed extremely fast to 4;500 [feet]; headed directly for Aircraft X. I told Aircraft X to climb immediately for traffic. He waited about 4 seconds to respond - which it seemed just about every single aircraft had been doing the entire session - and then asked 'Verify you want Aircraft X to climb?' I screamed 'Yes; climb now!' The aircraft maybe had 300 feet separation when their targets merged. This is just one example during that session; but I had at least 2 similar situations that I was able to resolve just a few seconds sooner than this one; avoiding such a close call (but it was still close). Oakland doesn't have the passenger enplanements to get Bravo airspace; but the arrival sectors Mulford/Grove are by far too complex and dangerous to only be using the Charlie airspace that we currently have. With the implementation of the new Bravo airspace at SFO that raised the base altitudes; VFR aircraft are doing overflights and practice maneuvers at altitudes that directly conflict with arrival traffic. All it takes is a moment of distraction; sector overload; or frequency congestion for a major disaster to occur. This is the Swiss Cheese model in full effect. We've been complaining about it for months now; but I guess it's going to take a major disaster to get the airspace changed. I nearly had 3 today in one session; and I was firing on all cylinders.




Synopsis: NORCAL TRACON Controller reported an unsafe situation attributed to IFR/VFR traffic and the lack of Class B airspace overlying the large airport in the airspace.