Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 5
Confusion; Distraction; Situational Awareness
ATC Issue All Types; Deviation - Altitude Overshoot; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Returned To Clearance
Human Factors
Aircraft X was issued pilot discretion descent to 9;000 ft. He started down and I was busy working other traffic and had large differences in altimeter settings between ZZZ and ZZZ1 areas. I saw him go down to 8;900 or 8;800 ft. and thought it may just be a bad altimeter setting or since I had several frequencies that maybe he got stepped on trying to tell me he had airport in sight and wanted to cancel IFR. So I gave him altimeter setting for the closest airport; then asked him to verify altitude. On the next radar sweep he was still descending so I issued a low altitude alert and had him climb back up to 9;000 ft. He climbed back up and let me know about some forest fires in the area.
A Center Controller reported an aircraft descended below its assigned altitude and flew below the Minimum Vectoring Altitude.