Cessna 172P N62731 accident near Townsend, Montana

Probable cause

The non-instrument-rated pilot's decision to conduct a cross-country flight over a mountain range in dark night conditions with limited night flight experience, which resulted in a collision with mountainous terrain.

NTSB analysis

The non-instrument-rated pilot notified his wife at 2211 that he would be departing the airport momentarily. The direct route to the destination of the dark night cross-country flight crossed a mountain range with elevations over 7,200 ft. The following morning, an emergency locator transmitter signal was detected, and the wreckage was subsequently located in the mountains at an elevation of about 5,000 ft along the direct route of flight. The wreckage pattern and ground scars indicated that the airplane impacted a rock formation on the face of a mountain during a steep right turn. An examination of the airframe and engine did not reveal any preimpact mechanical malfunctions or anomalies that would have precluded normal operation.

Although the pilot had accumulated some experience crossing the mountain range, he had never completed this flight in nighttime conditions, and he had only 3.8 hours of night flight experience. The pilot's wife reported that she had made the flight several times with the pilot, and he would typically fly over the mountain range unless the clouds were low, in which case he would take a longer route to avoid the mountains. The departure airport was reporting an overcast cloud layer that was about 8,000 ft mean sea level. Further, a witness at the destination airport reported that the sky condition was "pitch black," which was likely the result of a partially illuminated moon blocked by the overcast layer. In addition, mountain obscuration due to smoke and haze was present at the time of the accident, which would have further decreased the pilot's ability to recognize obstructions. As stated in a January 2008 National Transportation Safety Board safety alert, Controlled Flight Into Terrain in Visual Conditions, "darkness may render visual avoidance of high terrain nearly impossible," and "the absence of ground lights may result in loss of horizon reference."

It is likely that the airplane collided with terrain because the pilot could not see and avoid the surrounding terrain given the dark night conditions and mountain obscuration. Pilot spatial disorientation may also have occurred due to multiple risk factors including the pilot's lack of night flight proficiency and his absence of mountain flying experience in dark night conditions. Because the airplane was in a steep turn, it could not be determined whether the pilot was trying to avoid terrain that he saw at the last minute or if he was disoriented and inadvertently banked the airplane.

Text from the NTSB. Open the NTSB docket for WPR15FA247 for the full record.