This time, the messages revealed that Boeing employees successfully persuaded Indonesia's Lion Air to forego forcing their pilots to use a full flight simulator to train them on the 737 MAX 8.

According to Bloomberg, which published unredacted copies of the messages, offering full flight simulator training to Lion Air would undermine a key selling point of the 737 MAX 8: The fact that Boeing advertised the plane as needing no additional training for pilots and crew, apart from a basic computer-based course.

One Boeing employee wrote in June 2017 - a little over a year before the deadly Lion Air crash in October 2018 that helped inspire the universal grounding of the plane by regulators - that "friggin Lion Air was pushing for a "flight sim."

However, the Boeing employee promised his co-workers that he would "unscrew" the situation.

"Now friggin Lion Air might need a sim to fly the MAX, and maybe because of their own stupidity. I'm scrambling trying to figure out how to unscrew this now! idiots," one Boeing employee wrote in June 2017 text messages obtained by the company and released by the House Transportation and Infrastructure Committee.