Jack Dura
The Bismarck Tribune, N.D.
(MCT)
Dec. 14—Authorities might never know what all happened in the sky before a fatal Bismarck air ambulance crash in 2018, but one expert sees a few possible answers to some questions that remain.
The National Transportation Safety Board on Dec. 3 released its final report on the Bismarck Air Medical crash the night of Nov. 18, 2018. Bismarck Air Medical pilot Todd Lasky, Metro Area Ambulance paramedic Chris Iverson and CHI St. Alexius Health nurse Bonnie Cook died in the crash.
They were on their way to Williston to pick up a neonatal patient when the Bismarck Air Medical Cessna 441 broke up in flight. The plane was destroyed.
The NTSB found the probable cause of the crash to be “The pilot’s failure to maintain control of the airplane in dark night conditions that resulted in an in-flight positive overload failure of the wings and the subsequent in-flight breakup of the airplane.” The board in its report lists “aircraft structural failure” as the “defining event.”
The plane had climbed to 14,000 feet before it entered a right descending turn and fell 7,800 feet in about 40 seconds, with debris landing in a snow-covered Morton County field northwest of Harmon Lake.
“Pretty much what the NTSB’s report is saying is that this flight was flying along normally and something happened to cause that aircraft to pretty much get out out of control, and in an attempt to recover from that out-of-control situation, (the pilot) unfortunately overstressed the aircraft and that’s what caused the structural failure,” said Anthony Brickhouse, an associate professor of aerospace and occupational safety at Embry-Riddle Aeronautical University in Daytona Beach, Florida.
He also is the manager of the university’s aerospace forensic lab and is a trained accident investigator. He’s worked in aviation safety for 22 years. The Tribune shared the NTSB report with him for his analysis.
“NTSB does a good job,” he said. “The NTSB doesn’t investigate accidents based on speculation. The NTSB investigates accidents based on factual information and the analysis of that factual information, and the probable cause — they say the pilot’s failure to maintain control of the aircraft in dark night conditions. They couldn’t say why he didn’t maintain control.”
什么是跳出Brickhouse可能性potential icing from cold conditions or spatial disorientation due to night darkness, but NTSB didn’t cite evidence of either. Spatial disorientation results when a pilot has no references, and in severe cases “you don’t know up from down,” Brickhouse said.
Evidence of icing wouldn’t exist at the crash site, Brickhouse said. Icing would increase the weight of a plane, “which robs you of performance,” he said. Icing also interferes with control surfaces on the wings, which “can cause problems,” he said.
Whatever happened to the plane occurred once the aircraft reached its cruising altitude, he said.
Those aboard the plane “would know that something wasn’t right” before the aircraft lost altitude, he said. Lasky sent no distress calls, but Brickhouse said pilots are trained to “aviate first.”
“If a pilot is trying to save the day, their first job is to try to get that aircraft under control, and making a radio call isn’t necessarily going to help get that aircraft under control,” Brickhouse said. “Pilots are taught to fly the plane.”
The report indicates the pilot tried a pull-up maneuver that exceeded parts of the wings’ integrity while trying to recover from a “spiral dive.”
“That pilot was trying to do everything (he) could to save the day,” Brickhouse said. “And unfortunately, the aircraft was overstressed, and once you overstress an aircraft, depending on to what extent, it’s going to structurally fail.”
Based on the report, the plane didn’t appear to have a flight data recorder or a cockpit voice recorder, he said. Either device or a lightweight data recorder could have offered more details related to the crash, he said.
The Tribune submitted a records request to the Federal Aviation Administration regarding Lasky’s pilot history, which yielded only his pilot certificate numbers and a record of the Bismarck Air Medical crash.
Bismarck Air Medical, Metro Area Ambulance and CHI St. Alexius Health have declined to comment on the NTSB’s final report of the crash.
Reach Jack Dura at 701-250-8225 orjack.dura@bismarcktribune.com.
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