The release of a batch of internal messages has raised more questions about the safety of Boeing's 737 Max.
In one of the communications an employee said the plane was "designed by clowns".
The plane maker described the communications as "completely unacceptable".
The 737 Max was grounded in March 2019 after two fatal crashes in Indonesia and Ethiopia, which killed almost 350 people in total.
Boeing said it had released the hundreds of redacted messages as part of its commitment to transparency.
The Federal Aviation Administration (FAA) and US Congress were given unredacted versions of the communications last month.
"These communications do not reflect the company we are and need to be, and they are completely unacceptable," Boeing said.
One unnamed employee wrote in an exchange of instant messages in April 2017: "This airplane is designed by clowns who in turn are supervised by monkeys."
Another message dating from November 2015 appears to show how the company lobbied against the aviation regulator's calls for a certain aspect of simulator training.
"We are going to push back very hard on this and will likely need support at the highest levels when it comes time for the final negotiation," the message said.
In February 2018, a Boeing worker asked a colleague: "Would you put your family on a Max simulator-trained aircraft? I wouldn't."
"No," came the reply.
Timeline: Boeing crashes
- 29 October 2018: A 737 Max 8 operated by Lion Air crashes after leaving Indonesia, killing all 189 people on board
- 31 January 2019: Boeing reports an order of 5,011 Max planes from 79 customers
- 10 March 2019: A 737 Max 8 operated by Ethiopian Airlines crashes, killing all 157 people on board
- 14 March 2019: Boeing grounds entire 737 Max aircraft fleet
US House transportation committee chairman, Peter DeFazio – who has been investigating the 737 Max – said the communications "show a coordinated effort dating back to the earliest days of the 737 Max programme to conceal critical information from regulators and the public".
The FAA said: "Any potential safety deficiencies identified in the documents have been addRead More – Source