Regional Jet 200 ER/LR (CRJ200)
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 4.0
Situational Awareness
ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance
Procedure; Human Factors; Equipment / Tooling; Airspace Structure
The aircraft had been switched to TRACON from Center. The aircraft was issued a vector towards final and descent to 7000 feet. As the aircraft was getting closer to the final it was issued a further descent to 5500 feet; this is very normal on an ILS Approach. The pilot read back 5500 feet. I turned my head to scan some strips that had printed out. I turned back and noticed the aircraft was indicating 5100 feet. I immediately told the aircraft to climb to 5500 feet which they did.The STARS R4.0 build has the capability to have altitude filters set in addition to the Minimum Safe Altitude Warning (MSAW) alarm. Unlike the MSAW alarm which only looks at projected path and the actual terrain this additional feature can be totally customization for specific areas in an airspace where a altitude 'hotspot' may exist and will flash the aircraft's datablock to help catch the controller's attention. This feature should be considered for use at BTV in specific area over both mountain ranges in our airspace.
A BTV TRACON Controller reported observing an aircraft descend below its assigned altitude and below the Minimum Vectoring Altitude.