While flying in mountainous terrain to show one of the passengers the Neihart, Montana, area, the pilot entered a canyon that started to narrow as the canyon’s walls rose. The pilot initiated a climb.
The Cessna 177 then experienced a downdraft followed by a second downdraft, and he found a low spot in the trees and attempted a climbing turn, however, the airplane would not climb and started brushing the trees. The airplane descended into the ground, and a post-impact fire ensued.
The accident resulted in one fatality, 1 serious injury and two minor injuries.
Weather charts revealed gusty wind conditions with vertical air mixing and an increased potential for turbulence in the accident area. Weather model soundings and simulations revealed that the layer from the surface through 10,000 feet mean sea level was unstable, indicating that the airplane likely encountered wind magnitudes as high as 30 knots, gusty winds, and updrafts and downdrafts in the mountainous terrain.
Further, the airplane likely experienced turbulence and encountered downdrafts with a tailwind component at a velocity between 100 and 200 ft per minute.
Calculation of the airplane’s weight and balance revealed that throughout the flight, the airplane was operating about 114 pounds over maximum gross weight and outside (forward) of the center of gravity envelope. It is likely that the airplane was unable to climb over the terrain as a result of the weight and balance configuration combined with the weather conditions in the area.
The NTSB determined the probable cause as the pilot’s failure to maintain clearance from terrain while maneuvering at low altitude in turbulent conditions over mountainous terrain. Contributing to the accident was the pilot’s improper decision to traverse the mountainous area with the airplane over its maximum gross weight and with a forward center of gravity.
NTSB Identification: WPR14FA362
This September 2014 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.