Arctic Aircraft CO INC S 1B2 accident near Salcha, Alaska, May 27, 2017

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

The pilot and passenger were searching for an overdue boat with the intent of landing at a remote unimproved airstrip located near the boat's intended destination. A witness reported strong wind conditions as she observed the airplane circle the airstrip. While the airplane was circling, its nose suddenly dropped, and the airplane descended in a near-vertical attitude to ground impact. She stated that the engine continued to run, and the airplane did not make any unusual sounds, other than an increase in engine rpm, during the descent. A postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. The observed damage to the airplane indicated that it impacted the ground in a nose-down, near-vertical attitude. The witness account and the damage to the airplane were consistent with the pilot failing to maintain sufficient airspeed while maneuvering, which resulted in the airplane's wing exceeding its critical angle of attack and a subsequent aerodynamic stall. The airplane's estimated gross weight at the time of the accident was about 130.5 pounds over its approved maximum gross weight of 1,650 pounds, and the airplane's estimated center of gravity was about 0.1 inches beyond the approved aft limit at gross weight. As excessive weight increases stall speed and an aft center of gravity decreases controllability, it is likely that the pilot's decision to operate the airplane over gross weight with an aft center of gravity contributed to the loss of control.

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.