Medium Transport; Low Wing; 2 Turbojet Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 2
Situational Awareness; Workload
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic
Airspace Structure; Chart Or Publication; Human Factors; Procedure
During North flow; I was working Arrivals. Aircraft X was on vectors for the ILS approach. After issuing Aircraft X his ILS approach clearance I scanned and noticed a VFR target climbing southbound. I issued traffic; but Aircraft X did not have the aircraft in sight. The target appeared to be continuing towards Aircraft X and started climbing; so I elected to cancel Aircraft X's approach clearance and issued a climb and turn to the East to avoid the traffic. I subsequently vectored Aircraft X back around and onto the approach.My previous reports involved the proximity of VFR targets to BFI arrivals when our airspace is in a South Flow. This report is a perfect example of the fact that this problem also exists when our airspace switches to a North Flow. The timing of this report is also a perfect example of how; even in a North Flow; this problem is continuous and always present.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 solutions 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 Controller reported vectoring an aircraft off of an ILS in order to avoid conflicting unidentified VFR traffic.