Internal messages between Boeing employees reveal that they mocked the 737 Max, the New York Times reports.
Two of the aircraft crashed in late 2018 and early 2019, killing 346 people.
The messages were part of a number of documents Boeing handed over to the US government.
In one set messages, employees mocked the design of the plane and their own colleagues, writing: “This airplane is designed by clowns, who are in turn supervised by monkeys”.
In another, sent before the first crash in October 2018, one staff member wrote: “Would you put your family on a Max simulator trained aircraft? I wouldn’t.”