What happened
The aircraft was being vectored for an ILSS RWY 21 approach under weather conditions consisting of rain, lightning, and light to occasional moderate turbulence. The flight instructor and student pilot continued the approach, and as the aircraft intercepted the glideslope, a brilliant flash of lightning occurred. Following this flash, the crew received off flags for both the localizer and the glideslope.
As the flight instructor instructed the student pilot to break off the approach, the airplane descended into the terrain. At the time of the accident, a convective SIGMET for embedded thunderstorms was in effect and had been broadcast to the aircraft; however, the flight instructor misinterpreted the SIGMET information and believed it did not apply to their specific area.