Air Traffic Control Fully Certified
Situational Awareness; Confusion
ATC Issue All Types; Deviation - Altitude Overshoot; Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Executed Go Around / Missed Approach; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Became Reoriented; General Flight Cancelled / Delayed
Airspace Structure; Human Factors; Procedure
Aircraft X checked in on the ILS approach. I issued him a landing clearance; requested current flight conditions; and issued the RVR. A couple minutes later on the approach I received a Low Altitude Warning. I immediately issued the Low Altitude Warning and the altimeter. Aircraft X responded with roger. I noticed that Aircraft X continued to descend and upon reaching 600 ft at about 4.5 miles out on the ILS approach; I suggested that he climb and begin the missed approach. The pilot responded in the affirmative but still continued to display on the radar that he was descending and then hit 500 ft at about 4 mile final. I double checked again that he was flying the missed and received an affirmative response. It was then that the pilot again responded that he was going missed approach. I immediately coordinated with Approach that I advised the pilot to fly the missed approach; received instructions from them to use the published missed approach and for Aircraft X to maintain 4000 ft. I issued the instructions and shipped Aircraft X back to Approach.I have no idea what the pilot was doing or what he was looking at on his equipment to create this situation. I am not sure what I could have done differently. I am pretty sure I saved this dudes life!
HIO Tower Controller reported issuing Low Altitude Warning to an aircraft on the ILS descended below the glideslope.