Accident Overview
A pilot flying a GPS approach deviated from the prescribed course and descended prematurely, resulting in controlled flight into terrain. The accident occurred in instrument meteorological conditions with a low ceiling over mountains. The pilot had been cleared for the GPS approach by radar control approximately 11 minutes prior to the accident and indicated awareness of the initial approach fix's location and crossing altitude. No difficulties navigating or requests for assistance were made during the approach.
Flight History
The pilot initially navigated along the prescribed course. Seconds after passing an intermediate fix that required a critical 75-degree course change, radar and radio contact with the pilot was lost. Rather than proceeding toward the final approach fix on the prescribed 153-degree course, the pilot's track averaged 107 degrees. Additionally, instead of maintaining the minimum altitude of 4,100 feet mean sea level (msl) until reaching the final approach fix, the pilot descended to 3,550 feet msl.
Accident Sequence
The airplane impacted a mountainside 5.9 nautical miles east of the prescribed course and 550 feet below the authorized altitude. The aircraft was equipped with a GPS receiver that included a moving map display. The reason why the pilot lost situational awareness and deviated from the intended course is unknown.
Aircraft Equipment
The airplane was fitted with a GPS receiver capable of displaying a moving map. No other equipment details are specified.
Conclusion
The accident resulted from the pilot not turning onto the prescribed course after the intermediate fix and descending below the minimum altitude for the route segment. The lack of situational awareness remains unexplained.