Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 8
Distraction; Situational Awareness; Human-Machine Interface
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert
Airspace Structure; Human Factors
Aircraft X was looking for a visual approach into ZZZ. The aircraft started descending on his own without a clearance. I issued a terrain alert and instructed the Pilot to climb back to a safe altitude. I notified the CIC (Controller in Charge) but they did not instruct me to issue a brasher. A low altitude alert warning should have to be manually disabled. I don't think it alerted because the aircraft was nearing his destination airport.
A Center Controller reported an aircraft descended from its assigned altitude and flew below the Minimum Vectoring Altitude. The Controller reported the Minimum Safe Altitude Warning did not activate.