Medium Transport; Low Wing; 2 Turbojet Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 2.6
Distraction; Situational Awareness
Conflict Airborne Conflict
Air Traffic Control Issued New Clearance
Airspace Structure
Working sector with VFR; high volume and complexity. Aircraft X on a vector and cleared for the ILS runway 13R approach to BFI. As I cleared Aircraft X; I scanned to see a VFR target NE of the final approach course at 2800 heading towards the final; so I issued the traffic. After a moment; I decided I did not like the situation; particularly the possibility that the VFR might descend into Aircraft X; so I canceled his approach clearance and gave him a vector off the localizer to the South. The VFR did not descend; so I descended Aircraft X to my MVA and advised him to expect a visual approach. Aircraft X reported the field and traffic in sight; so I cleared him for the visual approach. Aircraft X indicated he would have to pass underneath the VFR again on the visual and wanted to verify he was cleared for the visual approach. I confirmed the approach clearance and indicated to the aircraft that if they wanted to descend it was more than understandable. Aircraft X subsequently continued to BFI and landed without further incident.This is another report of a continued problem within our airspace. As with [another report]; there was a lot going on in the airspace at the time and had traffic not been observed and a TCAS-RA resulted; it could have been much worse. The back-to-back timing of this event with my previous is a perfect illustration of how often the potential for these scenarios exist in our airspace. I wish I could get more of my coworkers to report them when they occur. Something needs to change. The VFR aircraft are transiting a very narrow; busy corridor of airspace and are doing so without any communication with ATC. It is simply unsafe. The VFR aircraft in this area at the very least need to be in communication with ATC so that we can assign; as necessary; altitude restrictions ensuring the safety of all the aircraft involved. The solution(s) are not hard and while they are potentially more restrictive to VFR aircraft the bottom line is that what happens day in and day out in that airspace as it exists and operates now will eventually result in a very bad accident.
S46 TRACON Controller reported multiple incidents where VFR aircraft have caused airborne conflicts in the BFI area.