Hefty POLAR CUB N62905

Summary

On 11 September 2016 at about 00:30 local time, a Hefty POLAR CUB registered N62905 was involved in an accident near Anchorage, Alaska, United States. One person was on board and one died. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

11 September 2016 at 00:30

Classification

Accident

Location

Anchorage, Alaska, United States

Coordinates

61.1253, -149.7489

Aircraft

Hefty POLAR CUB

Registration

N62905

Category

Airplane

Year built

1996

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Anchorage → Anchorage

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

ANC16FA065

1 person died.

The pilot's severe impairment from carbon monoxide poisoning in flight, which resulted in a loss of control and a subsequent collision with trees and terrain.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The private pilot departed in his float-equipped, experimental, amateur-built airplane during day visual meteorological conditions. According to a friend of the pilot, the purpose of the flight was to fly over a proposed hunting site and then return. About 90 minutes later, multiple witnesses saw the airplane complete two, low-level, high-speed, 360° right turns over a residential neighborhood. The witnesses said that the airplane's first 360° turn was accomplished at an altitude between 150 and 200 ft above ground level, but the second turn was much lower. Witnesses near the accident site reported that, as the airplane completed the second, steep, 360° turn, the nose of the airplane pitched down, and the airplane began a rapid nose-down descent. The engine rpm then increased significantly, and the wings rolled level just before the airplane impacted a stand of tall trees adjacent to a home. The airplane subsequently descended onto a neighborhood road and came to rest inverted. A postcrash fire ensued about 30 seconds after impact, which quickly engulfed the entire airplane.  According family members and close friends, this was highly unusual behavior for this pilot. Postaccident examination of the airplane's exhaust system revealed that the muffler can assembly was cracked around most of its circumference near the inlet portion of the muffler, which would have allowed exhaust gases to enter the cockpit/cabin. Toxicology tests revealed 48% carboxyhemoglobin (carbon monoxide) in the pilot's blood. The pilot was a nonsmoker, and nonsmokers normally have no more than 3% carboxyhemoglobin. The pilot's cause of death was extensive blunt force trauma including lacerations of the aorta, heart, and liver, and there was no soot found in his trachea. Although there was a postimpact fire, given the extensive blunt force injuries the pilot sustained and the lack of soot in his trachea, it is likely that the pilot's elevated carboxyhemoglobin level was from acute exposure to carbon monoxide during the 90-minute flight and not from postimpact fire. Carboxyhemoglobin levels between 10% and 20% can result in confusion, impaired judgment, and difficulty concentrating, and the pilot's 48% carboxyhemoglobin level likely resulted in severe impairment. No aircraft maintenance records were located for the airplane, which the pilot had built in 1996, so it is unknown when the muffler was last inspected or maintained. Additionally, due to the extensive postimpact fire, it was not possible to determine if the airplane was equipped with any type of carbon monoxide detection equipment. According to friends of the pilot, he conducted all maintenance on the airplane.

Quoted verbatim from the NTSB record.