Boeing (BA) employees ridiculed the 737 Max‘s regulatory certification progress and crudely expressed doubts about the plane‘s ability to fly safely, according to a trove of newly released internal documents.

The company on Thursday sent the documents — more than 100 pages in all — to the House and Senate committees that have been probing its design of the troubled 737 Max plane, which was grounded last March after two fatal crashes that claimed 346 lives