What happened
While conducting an ILS approach to the destination airport, the aircraft remained laterally aligned with the inbound approach course. However, the flight path remained above the glideslope before descending through it approximately 7 miles from the runway. The aircraft continued a gradual descent until it impacted wooded terrain roughly 3 miles from the approach end of the runway. There were no fatalities reported in this accident.
The investigation
An examination of the aircraft revealed no mechanical deficiencies. The airport was equipped with a Minimum Safe Altitude Warning System (MSAW) intended to alert controllers of potential terrain or obstruction collisions. Review of system documentation and radar replay confirmed that a low-altitude alert was displayed on the radar screen and an alert message was sent to activate the MSAW alarms.
Findings
Although the approach controller had transferred control of the aircraft to the local controller, the approach controller continued to monitor the flight. Upon noticing the aircraft descend below the glidepath, the approach controller 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.
The pilot had 470 total hours of flight experience and 92 hours of actual instrument flight time. During the six months preceding the accident, the pilot had accumulated only 2 hours of instrument flight time.