A former Boeing manager who claims he warned the aircraft manufacturer of systematic problems at its manufacturing base near Seattle just weeks before two 737 Max crashes killed hundreds of people, will testify before congress later this week.
In the lead-up to his appearance before the investigation committee, Ed Pierson told NBC News the pressure to pump out as many new planes as possible created a "factory of chaos."
He claims staff at the factory were working 50-60 hours a week, for weeks on end, without any days off.
Emails obtained by the broadcaster show Pierson was relentless in his efforts to convince the US Federal Aviation Administration and National Transportation Safety Board to investigate conditions at the factory.
Pierson told management his "internal warning bells" were ringing, adding: "For the first time in my life, I'm sorry to say that I'm hesitant about putting my family on a Boeing airplane".
The former boss implored Boeing to reduce the number of aircraft being made in order to let staff catch up and finish the ones that were already in progress.
He said his suggestion was ignored, and just weeks after his email a 737 Max built at that same factory crashed in Indonesia, killing all 189 people onboard.
Pierson said he was devastated to hear the news.
"I cried a lot," he said.
"I'm mad at myself because I felt like I could have done more," Pierson told NBC News.
Pierson then took his concerns directly to Boeing's board of directors. In a letter to them, he said he didn't want to "wake up one morning and hear about another tragedy and have personal regrets".
Just 19 days later, another Boeing 737 Max crashed - this time in Ethiopia and killing 157 people.
Despite the massive death toll, Pierson believed he still wasn't being listened to, so decided to speak to the media as a "last resort".
Boeing has now responded to Pierson's claims, telling NBC his concerns "received scrutiny at the highest levels of the company".
Pierson said the final straw came after meeting management about his concerns and telling bosses he'd "seen military operations shut down for a lot less safety concerns".
The bosses responded with an answer that convinced Pierson to speak out. "The military's not a profit-making enterprise," he claimes management replied.
Pierson, who retired in August 2018, will speak to the US congress investigation committee in Washington DC on Thursday (NZ time).