Date: 201602
Local time of day: 1801-2400
Location: S46.TRACON, WA
Flight conditions: VMC
Aircraft: Bombardier Learjet Undifferentiated or Other Model
Operator: Corporate
Operating under: Part 91
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class B S46; Class D ZZZ
ATC / advisory: TRACON S46
Second aircraft: Small Aircraft
Reporter organization: Government
Reporter function: Approach
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness
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 Issued New Clearance; Air Traffic Control Separated Traffic
Contributing factors: Procedure; Airspace Structure; Airport; Human Factors
Primary problem: Airspace Structure

Narrative: Aircraft X was on the ILS approach. I noticed a VFR target northeast of his position on a track to cross his final approach course. The VFR's Mode-C indicated 2;500 feet. I issued traffic; canceled the approach clearance and descended Aircraft X to 2;100 feet. This violated a local notice. The Minimum Vectoring Altitude (MVA) in the area prohibited me from getting 500 feet between Aircraft X and the indicated altitude of the VFR target. I did not have time to go through the required phraseology to have Aircraft X maintain his own terrain and obstruction clearance and go below the MVA. The traffic subsequently passed Aircraft X and I re-cleared the Aircraft X for the ILS. I was surprised that Aircraft X did not report a TCAS-RA.This is a routine and common problem in this portion of our airspace. I have previously filed a systemic ATSAP report regarding this particular safety problem. The base of the Class B airspace overhead the localizer is 3;000 feet; so VFR aircraft transit the airspace across and along the ILS localizer anywhere between 2;000 feet and 2;900 feet. We vector the IFR traffic onto the localizer at the published crossing altitude for a fix on the approach. There are a number of potential solutions. One solution would be to republish the altitude for the ILS Approach to [this delta airport] with a lower crossing altitude. This would allow us to be 500 feet below any VFR traffic at or above 2;500 feet. Another solution would be to change the airspace in such a manner as to sterilize the airspace along and in the vicinity of the final approach course to and prevent VFR aircraft from operating in the vicinity above 1;500-2;000 feet; perhaps by instituting Class C airspace. 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 altitude restrictions ensuring the safety of all the aircraft involved. In a potential nightmare scenario; a VFR aircraft could transit this airspace at an altitude which would cause the ILS Approach arrival to initiate a TCAS climb; which could climb them directly into traffic descending overhead. 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.




Synopsis: A Controller had to cancel an aircrafts' approach clearance and issue instructions to avoid a VFR aircraft crossing the final approach course not in communication with ATC. The reporter states this is a routine occurrence in this area.