NTSB Report: Cause of 2018 Denali Park crash to remain unknown

The wreckage of an Aug. 8, 2018 crash that killed all five aboard. The National Transportation Safety Board says that over the winter of 2018-19, 4,000 to 6,000 tons of ice calved from the Thunder Mountain hanging glacier, which it believed buried the plane. (Image from NTSB)
By  | 

ANCHORAGE, Alaska The final report by the National Transportation Safety Board into a 2018 crash in Denali National Park that left all five on board dead couldn’t determine a conclusive reason for the crash.

That’s largely because of the crash location: a steep hanging glacier at over 10,000 feet known as Thunder Mountain. That made recovery impossible, a task compounded by the fact that the glacier calved over the winter of 2018-19, burying the plane in up to 6,000 tons of ice.

Normally, toxicology reports are conducted on pilots on board and mechanical assessments are done on the wreckage, but since the plane was never recovered, those evaluations couldn’t be completed.

The De Havilland DHC-2 had been out on a one-hour-long air tour around Denali National Park and Preserve. Forty-eight minutes into the flight, the Alaska Rescue Coordination Center got an alert from the plane’s emergency locator. A few minutes later, personnel from K2 Aviation, the plane’s operator, got a call from the pilot in which he reported that the plane had “run into the side of a mountain.”

Poor weather conditions hampered early location efforts, and the plane wasn’t found until 36 hours after the crash. An on-scene assessment found that a wing had hit the snow while the airplane was flying in what was likely reduced visibility.

Weather analysis also found less-than-ideal conditions at the time and location of the crash. Winds blowing from the southwest at about 6 knots were compounded by “light-to-moderate rime icing in clouds” as well as precipitation.

While it couldn’t make any conclusions about the cause of the crash, the National Transportation Safety Board did make note of some company protocols concerning how pilots are notified of weather conditions. The company, it noted, did not use a formal risk assessment process, and instead relied on conversations between the pilots and the flight follower in either Talkeetna or Anchorage.

“This could lead to an oversight of actual risk associated with a particular flight route and weather conditions,” wrote the report’s investigator, David Williams.

The NTSB also noted that pilots were not required to report changes to planned flight routes to base operations.

The operators of K2 were out of the country Wednesday and could not be reached for comment about any changes in pilot or dispatch protocol.