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.”
The documents appear to show that Boeing rejected training pilots on simulators, which would have led to higher costs for the firm.
On Tuesday this week, Boeing reversed its position by recommending 737 Max simulator training for all pilots.