Cessna 170B N2746D accident near North Pole, Alaska

Probable cause

The pilot’s exceedance of the airplane’s takeoff performance limitations, which prevented the airplane from gaining sufficient altitude to clear the trees off the departure end of the runway.

NTSB analysis

During the takeoff of the personal flight, the airplane was unable to gain enough altitude to clear the trees off the departure end of the runway. Subsequently, the airplane impacted the trees and came to rest inverted, and a postaccident fire ensued, which destroyed the airplane. The pilot told the responding law enforcement officer that he thought that the wind had shifted during the takeoff and that the airplane lost lift at the end of the runway.

A postaccident examination of the airplane revealed no evidence of preaccident mechanical malfunctions or failures that would have precluded normal operation.

At the time of the accident, the airplane was departing from a grass/turf-covered runway, during a hot summer day, with full main fuel tanks, with a total of four occupants on board, and an estimated density altitude of 2,186 ft above mean sea level.

The pilot reported that the airplane was about 13 pounds more than its maximum gross takeoff weight.

The airplane owner’s manual indicated that at a maximum gross weight the airplane would need an estimated takeoff distance of 2,250 ft to clear a 50-ft obstacle. The accident site is a 2,400 ft long, by 100 ft wide, turf-covered site. The airplane manufacturer added that the turf runway would likely add to the distance needed for the takeoff.

Thus, given the conditions of the accident, the pilot likely exceeded the airplane’s takeoff performance limitations, which resulted in the airplane not attaining the altitude needed to clear the tree line during takeoff and the subsequent impact with trees.

Text from the NTSB. Open the NTSB docket for ANC21LA056 for the full record.