An independent inquiry into the crash has taken evidence from former major Ian Wilson, who was a test pilot with the Army Aviation Test and Evaluation Section before he retired in 2022.
Mr Wilson said the MRH 90 TopOwl night vision system was assessed as being unairworthy by AATES, because it had multiple defects which could lead to spatial disorientation, resulting in controlled flight into terrain, or crashes.
"Despite these warnings, individuals used their authority to compel the use of a system which was assessed as being both unairworthy and unsafe by its own flight test agency," he told the inquiry on Friday.
"The risk predicted in the AATES report has now tragically materialised."
The 2019 AATES report, which Mr Wilson helped draft, makes at least three references to "unacceptable risk to flight safety".
The Taipan helicopters had been deployed to an exercise on Lindeman Island before one crashed. (AP PHOTO)
Mr Wilson said he broke the chain of command by briefing SO1 and SO2 (officers) at the Standards branch regarding their obligations under the Workplace Health and Safety Act, and that should anyone die as a result of their actions, "it would, in my mind, be industrial manslaughter".
"We'd tried a number of approaches to be conciliatory and collaborative. They were not working," he said.
"In one particular meeting, I escalated the language to the point where I was threatened with disciplinary action. We backed off, and I then prepared that brief ... and I was laughed at by delivering that brief."
Mr Wilson also referred to an in-flight incident on a MRH-90 in which his co-pilot had become disoriented as "the closest I've come to crashing".
"I have seen every experience … I don't become alarmed easy. That was a very alarming incident. I was convinced that someone would crash because of that," he said.
Addressing the victims' families at the inquiry, Mr Wilson said: "having escaped losing my own life and that of six of my crew members in very similar circumstances, I knew with certainty this accident was going to happen.
"I had a moral obligation to your loved ones. I did the best I could and I failed them. I'm so sorry for your loss."
Former justice Margaret McMurdo is leading the inquiry into the fatal Taipan helicopter crash. (Darren England/AAP PHOTOS)
The inquiry into the crash of the MRH-90 Taipan helicopter in July last year is being conducted by former justice Margaret McMurdo.
Captain Danniel Lyon, Lieutenant Maxwell Nugent, Warrant Officer Class Two Joseph Laycock and Corporal Alexander Naggs all died in the crash.
Their aircraft, call sign Bushman 83, was one of four choppers tasked to fly to Lindeman Island to collect Australian Defence Force personnel who were conducting an exercise.
The inquiry's sixth public hearing starts in Brisbane on November 18.
