Grant Aviation Flight 262

The commercial certificated pilot and six passengers were en route between remote villages on a VFR scheduled commuter flight. The pilot contacted the village agent at the destination airport via radio, and received a weather report as 800 feet overcast, with the visibility as 5 miles. The director of operations for the company reported that the weather at the accident scene was an indefinite ceiling of about 500 feet, and a visibility of about 2 miles. After departure, the pilot proceeded toward the destination airport about 450 feet above the ground. About 10 minutes after departure, the pilot said the horizon began to become obscured and the area ahead of the airplane turned white. He said there was no precipitation, rather the ground and sky became indistinguishable. He began a right turn toward the east, but about 2 seconds after beginning the turn, the airplane suddenly collided with snow-covered terrain. A passenger reported the visibility was about 1 mile under gray skies. The airplane was equipped with an avionics package provided by the FAA's Capstone Program. The Capstone Program is a joint industry/FAA demonstration program that features, among others, global positioning system (GPS) avionics, weather and traffic information provided through automatic dependent surveillance-broadcast (ADS-B), traffic information service-broadcast (TIS-B) equipment, and terrain information depicted on a multifunction display (MFD) installed in the cockpit. The Capstone program provides radar-like services to participating air carrier aircraft operating in a nonradar environment of Western Alaska. Terrain depiction information, based on GPS data, is one of several visual display options available to the pilot on the MFD. Selection of the terrain mode for display, provides the pilot with color shading depicting areas of terrain that are black (2,000 feet below the aircraft), green (between 2,000 and 700 feet below the aircraft), yellow (between 700 and 300 feet below the aircraft), and red (at or within 300 feet of the aircraft). Accurate depiction of terrain (in the terrain mode) requires the pilot to manually set a barometric pressure setting in the MFD menu. The Capstone avionics equipment does not receive barometric pressure data from the aircraft's altimeter. Selection of the map mode does not provide any terrain awareness information. During the interview with the NTSB IIC, the pilot said that he selected the moving map display with a five mile scale. He did not observe any warning flags illuminated on the MFD, and he did not manually enter any barometric pressure data into the MFD. The pilot said that he routinely utilized his own personal GPS receiver that has a color moving map display. He said he is more familiar with his own GPS, and had it installed on the top of the instrument panel glare shield. He said that since the terrain in Western Alaska is usually quite flat, he routinely utilized the Capstone map mode with the GPS "go to" function for each leg/destination of a route, not the terrain mode.

Verbatim NTSB analysis and probable cause from the NTSB dataset