Cessna 172R accident near Missoula, Montana, July 1, 2021

The NTSB's narrative final · quoted from the NTSB record

The pilot and passenger departed on a personal flight to an unknown destination. The airplane’s weight for the flight was about 68 pounds above the maximum gross takeoff weight. The airplane proceeded westward, overflew rising mountainous terrain, and entered a box canyon. The last recorded data point, about 3.3 miles east of the accident site, showed that the airplane was at an altitude of about 678 ft above ground level; on a magnetic heading of 271°; and at a groundspeed of 68 knots, which was 17 knots faster than the published stall speed. The airplane impacted terrain in a low-energy, nose-low attitude, and nearly vertical descent with a small debris field, consistent with an aerodynamic stall. High-density altitude conditions at the departure airport prevailed, and no turbulence, low-level wind shear, or obscurations existed near the accident site. The available evidence for this investigation precluded a determination of whether the airplane continued to climb and maintained its airspeed as it progressed toward higher terrain. However, the combination of the airplane’s exceedance of the maximum takeoff gross weight and the high-density altitude likely resulted in degraded airplane climb performance and increased the time required to reach a suitable altitude to maintain clearance from the surrounding terrain.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.