Date: 201810
Local time of day: 0001-0600
Location: NCT.TRACON, CA
Flight conditions: Marginal
Weather elements / visibility: Cloudy
Aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach; Final Approach
Airspace: Class B SFO
ATC / advisory: TRACON NCT
Second aircraft: Widebody; Low Wing; 2 Turbojet Eng
Reporter organization: Government
Reporter function: Approach
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness; Workload; Confusion
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic; Flight Crew Executed Go Around / Missed Approach; Flight Crew Requested ATC Assistance / Clarification; General Flight Cancelled / Delayed
Contributing factors: Weather; Airspace Structure; Staffing; Company Policy
Primary problem: Weather

Narrative: The Finals Sectors were working side by approaches into SFO when I overheard TMU (Traffic Management Unit) get a call from Tower mentioning the field might go IFR due to a layer moving in. I had coordinated with the other Finals controller that Air Carrier X was going to follow Air Carrier Y. I descended Air Carrier Y until they obtained visual separation. Once Air Carrier X was providing visual separation with Air Carrier Y I cleared Air Carrier Y for the Charted Visual approach. At which time the Front line supervisor mentioned we were IFR and transitioning to closely spaced ILS approaches.Shortly after the new ATIS came out and the airport was IFR. Air Carrier X was already on an ILS approach to the left runway providing visual separation with Air Carrier Y on the right runway approach. They sent Air Carrier X around for either being too high or due to the confusion that is going around in the area with visual separation with aircraft on parallel runways. The Supervisor came over and told the other Finals controller to combine the sectors and he did just that without a briefing due to the traffic and confusion. The controller configured my airspace and took my frequencies while I had much work to do. I believe the Supervisor made this choice due to him needing to open up another position because that controller was not accepting any more planes from Center.While sitting on my sector without my airspace I hear Air Carrier Y mention he's going around and he's on a 3 mile final around 1;800 feet. I cancelled his clearance and climbed him to 4;000 feet (instead of 3;000 feet SOP) and instructed him to fly runway heading. I called Departure Control and let them know despite there being a lot of confusion on the landline. So happens that Air Carrier X also went around and was 2.74 miles ahead also flying runway heading instead of 265. This event might have occurred due to the confusion in the area due to the visual separation to parallel runways while one is on an instrument approach. I recommend we get clarification on applying visual separation so we don't have unnecessary go arounds due to confusion of how to apply a rule or procedure. Also the weather moves in and out of SFO often and having the staffing to open positions would help; oppose to having to juggle open and close sectors to make it work.




Synopsis: NCT TRACON Controller reported two aircraft going around from parallel runways resulted in less than the required lateral separation.