Approach and Descent
While flying the Instrument Landing System (ILS) approach to the destination airport, the airplane remained laterally aligned with the inbound approach course. However, it remained above the glideslope and subsequently descended through it approximately 7 miles from the runway. The airplane continued a gradual descent until it impacted wooded terrain roughly 3 miles from the approach end of the runway.
Aircraft and System Examination
Examination of the airplane revealed no mechanical deficiencies. The airport was equipped with a Minimum Safe Altitude Warning System (MSAW) designed to alert controllers when an aircraft is in danger of colliding with terrain or obstructions. Examination of system documentation and the radar replay indicated that a low-altitude alert was displayed on the radar screen, and an alert message was sent to activate the MSAW alarms.
Controller Actions
The approach controller had transferred control of the airplane to the local controller but continued to monitor the airplane on the approach. When the approach controller noticed the airplane descend below the glidepath, he notified the local controller. The local controller's radar display also indicated a low altitude alert. However, the local controller's first instruction to the pilot to "climb" occurred 5 seconds after the last target was observed on radar.
Pilot Experience
The pilot reported 470 total hours of flight experience and 92 hours of total (actual) instrument flight time. During the preceding 6 months, the pilot accumulated 2 hours of instrument flight time.