Small Aircraft
Flight Crew Flight Engineer; Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Multiengine; Flight Crew Instrument
Confusion; Training / Qualification; Human-Machine Interface
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance
Flight Crew Returned To Clearance; Flight Crew Became Reoriented; Flight Crew FLC complied w / Automation / Advisory
Human Factors; Environment - Non Weather Related
I was on a vector with ZZZ approach for a visual to Runway XX and a descent clearance to 3;000 MSL.  Passing through 3;000 the altitude alert flashed and I thought it was a 1;000 foot warning.  At 2;600 MSL I realized my mistake and made an immediate climb back to 3;000 MSL.  Approach made no mention of my deviation and a few minutes later cleared me for the visual to Runway XX.There were a few factors involved. The attitude indicator and heading indicator had been recently replaced with two glass displays.  Though I had flown plenty of glass in the past; these instruments are still somewhat new to me. I had also taken time off earlier in the year and combined with COVID-19 had not done any flying.  I had planned on going out with an instructor before the flight; but the social distancing with COVID-19 made me decide against doing that. I made a few flights totaling 7 hours during a two week period before the date of the incident by myself doing basic and commercial air work; takeoffs and landings and just getting familiar with the plane again.  In March I also did several approaches and holds in a flight simulator. The simulator was configured with a standard six pack.No excuses on my part.  I momentarily got behind the airplane and had some confusion with what one of my instruments was telling me.
GA pilot reported misinterpreting an altitude alert and descended from assigned altitude while on approach. Lack of familiarity with the instrument panel and lack of recent flying due to the COVID-19 pandemic were cited as contributing factors.