B737-700
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 10.0
Communication Breakdown; Situational Awareness; Human-Machine Interface
ATC Issue All Types; Conflict Airborne Conflict
Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic; Flight Crew Executed Go Around / Missed Approach; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Took Evasive Action; General Flight Cancelled / Delayed
Chart Or Publication; Human Factors; Airspace Structure; Procedure
Aircraft X was cleared for the ILS 26R into ONT by the Norton Controller. He was established on descent and shipped to Tower. I was on a different sector and noticed a VFR aircraft north of the final at 2500 feet turn south on track to fly over/west of SCRIM. I advised the Norton Controller of traffic and he called the Tower to issue a traffic advisory to Aircraft X. If Aircraft X had remained on the glide path; he would have crossed directly over the traffic with less than 200 feet separation. Instead; Aircraft X responded to an RA and went around at which time he was my control.The Class C airspace design for ONT continues to pose an unnecessary hazard to IFR arriving aircraft. At present; transitioning aircraft can fly over the Final Approach fix of the ILS approach up to; but not including; 2700 feet. With new approach profiles; this affords zero protection for IFR aircraft at a critical phase of flight. The Class C surface area must be extended at least 4 miles east of the final approach fix in order to ensure clearance from arriving aircraft as well as affording the Finals controller two way communications with transitioning VFR aircraft to ensure separation and safety.
SCT TRACON Controller observed an arriving air carrier on an ILS approach respond to an RA due to a conflict with an unidentified VFR aircraft.