Introduction
The accident occurred during a commercial visual flight rules (VFR) flight conducted by an airline transport pilot. The flight comprised two segments: the first with a passenger and the second carrying a load of mail. After the passenger disembarked from the first segment, the pilot departed on the second leg, which involved crossing a peninsula of mountainous terrain to a remote coastal airport without official weather reporting or instrument approach procedures.
Flight Details
Approximately 28 minutes after departure, an emergency locator transmitter (ELT) signal from the aircraft was received, initiating a search and rescue operation. The wreckage was located about 24 miles from the destination, resting in deep snow on the side of a steep, featureless mountain at an elevation of about 3,000 ft mean sea level. Impact signatures were consistent with a collision during a left turn. Examination revealed no evidence of mechanical malfunctions or anomalies that would have precluded normal operation. The aircraft was not equipped with any recording or flight tracking devices, nor was it required to be; therefore, the flight path before the accident could not be determined.
Weather and Conditions
A review of nearby weather camera images showed complete mountain obscuration with likely rain shower activity near the accident site. Visible and infrared satellite imagery indicated overcast cloud cover over the accident site at the time. Graphical forecast products available to the pilot before departure indicated marginal VFR conditions for the entire route. There was no evidence that the pilot obtained an official weather briefing, and what weather information he may have accessed could not be determined. Additionally, the cloud conditions and snow-covered terrain likely resulted in flat light conditions, hindering the pilot's ability to perceive terrain features and closure rates. Based on weather camera, surface, and upper air observations, it is likely that the pilot encountered instrument meteorological conditions (IMC) in flight, after which he performed a left turn to return to visual meteorological conditions (VMC) and did not recognize his proximity to the mountain due to flat light.
Company Procedures
The aircraft was certified for instrument flight and flight in icing conditions and was equipped with a terrain avoidance warning system (TAWS) that was not inhibited. Although the TAWS should have provided alerts as the aircraft neared terrain, it could not be determined if alerts occurred or if the pilot heeded them. The pilot and the dispatch agent signed a company flight risk assessment form before the flight, which indicated that the weather conditions were within the company's acceptable risk parameters. However, the assessment was based on hours-old observations provided by a village agent who was not trained in weather observation and did not include en route weather information, the area forecast, or the AIRMET for mountain obscuration effective during the dispatch time and at the time of the accident. Since acquiring the accident route from another operator years earlier, the company had not performed a risk assessment of the route and its associated hazards. Multiple company pilots described the accident route as hazardous due to terrain, rapidly changing weather, and lack of weather reporting infrastructure, but the company did not address these known hazards through its risk assessment processes. The company's controlled-flight-into-terrain (CFIT) avoidance program required each pilot to have one classroom training session and one CFIT-avoidance training session in an aviation training device (ATD) each year; however, the pilot's training records showed his most recent ATD session was 15 months prior. More recent CFIT avoidance training might have enabled the pilot to recognize and respond to reduced visibility and flat light conditions sooner.
Probable Cause
The official findings state that the probable cause of the accident was the pilot's continued VFR flight into an area of mountainous terrain and instrument meteorological conditions, which resulted in controlled flight into terrain. Contributing to the accident was the company's failure to provide the pilot with CFIT-avoidance recurrent simulator training as required by their CFIT avoidance program, and the company's inadequate flight risk assessment processes, which did not account for the known weather hazards relevant to the accident route of flight.