Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 10
Situational Awareness
ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; 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
Airspace Structure; Human Factors; ATC Equipment / Nav Facility / Buildings; Procedure
I vectored Aircraft X for an ILS approach. After the initial vector I gave the following information; distance from FAF; heading to 230; maintain 6000 ft until established; cleared for ILS approach. After giving the clearance my Radar Assist mentioned my turn on angle was too great; I then corrected it and issued a 240 heading to intercept the localizer. The aircraft was descending quickly and was in and out of radar contact. In my scan I noticed I had lost radar contact for one update; next update it was back but their altitude was 5600 ft. I issued a low altitude alert; the next update was 5100 ft. I again issued a low altitude alert and asked Aircraft X to climb immediately to 6000 ft. At that time my intention was to terminate their approach and try again. I waited for altitude to start a climb then did so. At that time the aircraft canceled IFR; in VFR conditions; and I switched them to tower.As this was a pilot deviation I feel my instructions were appropriate. My correction of the heading was the only thing that I felt was lacking and it was forced under pressure.
ZSE Center Controller reported that an aircraft descended too early for the approach; and went below the minimum safe altitude.