Boeing's chief executive Dave Calhoun faced a grilling from US senators about the company's culture as he apologised to family members of plane crash victims, who shouted at him throughout the hearing.
Mr Calhoun testified on Tuesday to Congress that the company had "learned" from past mistakes and that the process for employee whistleblowers "works" - but lawmakers still accused him of not doing enough to rectify a culture of retaliation.
The US company most recently was put in the spotlight when a door panel fell off a new 737 Max plane during an Alaska Airlines flight in January, leaving a gaping hole.
As part of an ongoing investigation, Boeing whistleblowers told the Senate in April that the 737 Max, the 787 Dreamliner and the 777 models had serious production issues.
Mr Calhoun, who became CEO in 2020 and plans to leave later this year, told the Senate sub-committee that some problems come from an "untrained workforce".
He blamed the layoffs and worker turnover that plagued the industry after Covid, saying they contributed to manufacturing issues at the company.
"So much of this is related to an untrained workforce. It's all about that, honestly," he said.
The company faced intense criticism five years ago, after two 737 Max aircraft were lost in separate, but almost identical accidents, killing 346 people.
Several family members of victims who died in those crashes attended the hearing, holding up pictures of loved ones. They spoke outside in a news conference beforehand.
“I flew from England to Washington DC to hear in person what the Boeing CEO has to say to the Senate and to the world about any safety improvements made at that corporation,” said Zipporah Kuria, whose father was killed in the 2019 crash of a Boeing 737 MAX 8 jet.
“I also continue to press the US government to hold Boeing and its corporate executives criminally responsible for the deaths of 346 people. We will not rest until we see justice.”
Clariss Moore, whose daughter died in a Boeing crash in Ethiopia in 2019, confronted Mr Calhoun, asking him during the hearing about “my daughter's last breath on the plane".
"Did she call for me? Did someone hold her hands?" she demanded.
Committee chairman Richard Blumenthal kicked off the tense hearing by thanking family members "for having the strength and courage to be with us".
He also demanded to know what Boeing was doing "to end this broken safety culture".
"I assure you that I listened to the whistleblowers," Mr Calhoun responded.
He added that he had not spoken to whistleblowers and acknowledged company retaliation against several.
“I know it happens,” he said, adding that he does not know how many employees were fired or disciplined for speaking out about safety issues.
During the hearing, Mr Calhoun rose and turned to say sorry to the families for their losses.
"They're gut-wrenching," he said, his voice seeming to break with emotion, "and I apologise for the grief that we have caused."
Boeing chief engineer Howard McKenzie testified that there "absolutely" was a culture of safety first within Boeing's engineering team.
After the hearing ended, Senator Blumenthal told OceanNewsUK that he was not satisfied with the CEO's answers, and that his probe would continue.
"I have a lot more questions that need to be answered and we're going to be pursuing our investigation," he said.
In May, the US justice department informed Boeing that it launched a criminal investigation into its practices.
Several family members on Tuesday said they hoped criminal charges would be filed against the company.
