Regional Jet CL65; Undifferentiated or Other Model
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) .8
Situational Awareness
ATC Issue All Types; Aircraft Equipment Problem Less Severe; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued New Clearance; Air Traffic Control Provided Assistance
Aircraft; Human Factors
I was working flight data when a low altitude alert sounded on Aircraft X on about a 10 mile final. The Radar Controller gave a low altitude alert with a local altimeter and asked the pilot to verify he was established on the localizer. The pilot stated he was and the Radar Controller switched the pilot to Local Control. It was at this time I noticed the pilot's altitude of 900 feet. and descending. I believe I saw a low of 600 ft. on the radar scope when the plane was approximately 6 miles away from the airport. The MVA in that area is 1800 ft. I reached out to Local to find out if they were speaking to the aircraft and they weren't at that time; but the Local Controller was able to get in touch with the aircraft and issued a go around instruction with a climb to 3000 ft. We queried the aircraft on what happened and the pilot stated that the autopilot disconnected; an instrument was not working properly and they did not receive any low altitude warnings in the cockpit. The aircraft was vectored for a second approach and the pilot hand flew the aircraft safety to the airport without incident. The low altitude alert was not issued properly; and the aircraft should not have been switched to Tower while that low to the ground.
Flight Data Controller reported a Low Altitude alert on an aircraft 1;300 feet below the Minimum Vectoring Altitude.