A former Boeing manager tried on multiple occasions to sound the alarm to superiors about unsafe work conditions at the airline company’s main factory months before two of its 737 Max airplanes crashed, killing nearly 350 people, a report said.

Ed Pierson told NBC News about how increased productivity demands starting in late 2017 at the Renton, Washington, Boeing plant led to an “out of control” environment that he felt could create mistakes in production.

At that time, Pierson said Boeing pushed for the increased production of five more 737 airplanes at the plant, from 47 to 52, the report said.

Because of a delay in parts, which caused a production slowdown, workers were forced to make up for lost time when they received the shipments. This led to long hours and out-of-sequence work, such as production steps done at times other than originally planned.

“It just became full speed out of control,” Pierson told the outlet of the plant’s demands. “The sheer volume was just overwhelming.”

“I know people that worked more than five weeks in a row,” he said.

The manager, who started at Boeing in 2015 and retired in 2018, is set to appear before Congress this week to describe his numerous attempts raise red flags through numerous channels. His recommendation to higher-ups, which was never heeded, was to temporarily shut down production at his plant.

In a nearly year span from the summer of 2018 to the spring of 2019, Pierson brought his concerns to Boeing executives, the FAA and the NTSB, according to emails obtained by NBC News.

In one June 2018 email to Scott Campbell, the general manager of the 737 Max program, Pierson wrote, “Frankly right now all my internal warning bells are going off.”

“And for the first time in my life, I’m sorry to say that I’m hesitant about putting my family on a Boeing airplane.”

Four months later, a 737 Max manufactured in Renton crashed into the sea near Indonesia, killing all 189 aboard.

“I’m mad at myself because I felt like I could have done more,” Pierson told the outlet. “I cried a lot.”

In February 2019, Pierson tried to get the attention of the Boeing board of directors.

“I have no interest in scaring the public of wasting anyone’s time,” Pierson wrote in an email.

“I also don’t want to wake up one morning and hear about another tragedy and have personal regrets.”

Less than a month later, on March 10, 2019, another 737 Max crashed in Ethiopia, killing all 157 passengers aboard.

“I really had hoped that by providing information to the right people, and following the protocols and the chain of command every step of the way, I thought people would do their job,” Pierson told NBC News.

Despite Pierson’s concerns about production distribution, Boeing noted that cause of both crashes weren’t linked to the factory issues he brought up.

Boeing, who said they took Pierson’s concerns seriously, has acknowledged both crashes were caused by problems with the planes anti-stall software, the report said.

“Mr. Pierson raises issues about the production of the 737 MAX, yet none of the authorities investigating these accidents have found that production conditions in the 737 factory contributed in any way to these accidents,” the company said in a statement to NBC News.

“Importantly, the suggestion by Mr. Pierson of a link between his concerns and the recent MAX accidents is completely unfounded.”

The planes have been grounded amid the ongoing investigations.