EMB ERJ 170/175 ER/LR
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 12.5
Communication Breakdown; Situational Awareness
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance
Airport; Airspace Structure
Aircraft X was descending into Boise on the PARMO3 arrival. The arrival; when landing east; crosses JIMMI at 5000 ft. We have two busy satellite airports west of Boise where traffic is consistently crossing the final close to JIMMI between 4000 ft. and 6000 ft. These VFR aircraft off of the satellite airports do not always call Approach Control and skirt around the class C airspace. This event happened at the time previously stated between Aircraft X and an unknown VFR aircraft that appeared to be descending into one of these satellite airports. I issued traffic to Aircraft X on the unknown VFR target; but they did not see them. Anticipating merging target procedures and to positively control the situation; I vectored Aircraft X into the adjacent Controller's airspace after performing the necessary coordination. This continues to be a systemic problem and action should be taken to avoid unnecessary risks into the NAS.I recommend that we make a Class C extension that extends out to 20 DME from 4500 ft.-6900 ft. This would force VFR aircraft that transition the area to contact Approach Control for clearance through this critical airspace while leaving enough ground clearance to allow aircraft who would like to fly under the airspace and not have to talk to Approach Control the ability to do so.We have had multiple pilot outreach programs to ask pilots from these satellite airports to call us up when they are going to go through that airspace above 4500 ft. They continue to do so; and; in several cases just turn their transponder off creating a further hazard to safety.
BOI Approach Controller reported they had to vector an aircraft off their published approach course due to converging unidentified VFR traffic.