NTSB: 'Structural failure' led to fatal 2018 air ambulance crash
A paramedic, nurse and pilot were killed when their plane broke up in flight over North Dakota
The Bismarck Tribune, N.D.
MORTON COUNTY, N.D. — A recent report in the federal investigation of a fatal 2018 air ambulance crash in Morton County indicates a structural failure led to the crash, though it doesn't pinpoint the exact cause of the tragedy that killed all three people aboard.
An aviation expert says the structural failure might have been a problem with a wing.
Pilot Todd Lasky, paramedic Chris Iverson and nurse Bonnie Cook died in the crash the night of Nov. 18, 2018, northwest of Harmon Lake. They were headed from Bismarck to Williston to pick up a neonatal patient when the Bismarck Air Medical Cessna 441 "broke up in-flight," according to a preliminary report.
The National Transportation Safety Board on Aug. 13 published its factual report, which outlines conditions and information of the aircraft, its wreckage, the weather and autopsies.
A final report, which could identify the probable cause of the crash, is expected in 12-18 weeks, according to Bismarck Air Medical Director of Operations Jonathan Ternes.
NTSB lists "aircraft structural failure" as the "defining event" in the new report. A "defining event" would be "the event that led to the accident," said University of North Dakota professor and Aviation Department Chairman Brett Venhuizen, with whom the Tribune shared the report.
Venhuizen noted a passage in the report's wreckage and impact information that "Further examination of the right wing showed it had separated at the fuselage."
"It seems to me that here (NTSB is) really focused on a structural failure," he said.
A variety of reasons could cause a structural failure, such as fatigue of a component, he added.
The plane wasn't struck by anything, nor was there was a fire or explosion, according to previous information released in the investigation. Weather also wasn't a factor. No distress calls were received.
The plane's left and right engines "showed no mechanical malfunctions or failure that would have prevented normal operation of either engine," the report said.
There also was no evidence of failure or malfunction of the propellers.
"Witnesses on the ground reported hearing high-pitch, high-speed engine sounds prior to impact," the report said.
The plane had climbed to 14,000 feet before it entered a right descending turn and fell 7,800 feet in about 40 seconds.
"I think that (fall) would be consistent with a structural failure. When a wing fails like this and folds up, the aircraft is going to just fall very quickly," Venhuizen said.
The plane was in a left descending turn seconds before it lost radar contact. The crash occurred in a snowy field.
"The NTSB does a very good job of investigating these accidents," Venhuizen said. "They definitely know what they're doing and are usually able to determine a cause."
Memorials were unveiled last year outside of CHI St. Alexius Health and Metro Area Ambulance in Bismarck in honor of Lasky, Iverson and Cook.
©2020 The Bismarck Tribune (Bismarck, N.D.)