Piper PA-18-150 N7154Z accident near Mcgrath, Alaska

Probable cause

The pilot's exceedance of the airplane’s critical angle of attack while maneuvering for landing, which resulted in an aerodynamic stall and loss of control.

NTSB analysis

The airplane departed from a remote hunting camp and traveled to a 2,500-ft ridge about 3.5 miles away to drop off supplies to a hunting guide; the pilot was planning to continue to an airport for fuel. According to the guide who was at the scene of the accident, the airplane flew over their camp several times before flying further up the ridge, where it executed several passes over the ridge. While the pilot had landed on this ridge in seasons past, this would have been his first time landing on the ridge this year.

The guide reported that winds near the accident site were about 15 mph from the northeast and the visibility was good. He reported that the airplane was traveling slow and low on a southwest heading and began a right turn to the northeast. As the airplane began what the guide thought to be a right base to final turn, he lost sight of the airplane. However, the guide reported that he could still hear the airplane’s engine. He reported hearing the engine “call for a lot of power” twice and a few seconds later he heard the airplane impact the ground.

The airplane was found nose down in a near-vertical attitude on a northeast heading on the south side of the ridge. The wings remained partially attached and the tail was bent slightly to the right. The wreckage pattern of the airplane was consistent with the airplane impacting the ground during a stall/spin.

The pilot and owner of the accident airplane had incorporated modifications to the airplane, including leading edge slats and slotted two-piece flaps. The leading edge slats were removed a few months before the accident. Although these modifications allowed for lower airspeeds during landing and altered the stall characteristics of the airplane, the investigation was not able to determine if the changed flight characteristics might have played a role in the experienced pilot’s exceedance of the airplane’s critical angle of attack while maneuvering.

A postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. Based on the available information, it is likely that the pilot exceeded the airplane’s critical angle of attack while maneuvering for landing, which resulted in an aerodynamic stall and loss of control.

Text from the NTSB. Open the NTSB docket for ANC24FA085 for the full record.