Cessna 172 N3720R accident near Seeley Lake, Montana

Probable cause

The noninstrument-rated pilot’s encounter with instrument meteorological conditions during a night visual approach due to wildfire smoke, which resulted in controlled flight into terrain.

NTSB analysis

The airplane with a noninstrument-rated pilot and two passengers onboard was on a night cross-country flight. A witnesses heard the airplane approach the destination airport from the south and continue past the airport to the north until he could no longer hear it. Local law enforcement personnel began a search for the airplane after witnesses reported hearing a crash, and they located the accident site early the next morning about 3/4 miles north of the airport.

The airplane impacted the top of about 75-ft-tall trees and traveled about 365 ft through the treetops on a heading of about 152° before coming to rest. The distance the airplane traveled through the trees was consistent with controlled flight into terrain, and the heading was consistent with a final approach to the airport’s south runway. Postaccident examination of the airframe and engine revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. The damage to the propeller was consistent with it rotating under power at impact.

A review of weather near the accident site revealed that many wildfires were occurring in the Pacific Northwest at the accident time. A westerly wind carried the smoke from these fires to the area of the accident site. The accident occurred after sunset and with an inversion over the accident site, which trapped and concentrated smoke between the ground and 1,000 ft above ground level. Visibility likely decreased to instrument flight rules levels due to the smoke, and the limited visibility was compounded by the dark night light condition. The first law enforcement officer at the accident site stated that there was haze, and that the visibility was between 1 to 3 miles. It is likely the airplane encountered instrument meteorological conditions (IMC) during the visual approach to the airport, which resulted in the pilot losing visual contact with the ground.

The IMC weather conditions, the airplane’s path through the trees on runway heading, and the evidence of normal engine operation were all consistent with the noninstrument-rated pilot’s-controlled flight into terrain during a night visual approach.

Text from the NTSB. Open the NTSB docket for WPR20LA304 for the full record.