Text messages between Boeing employees in 2016 indicate that the company was aware of issues with the 737 Max that contributed to two fatal crashes in the last year, Reuters and The Washington Post report. In the text messages, the aircraft’s then-chief technical pilot, Mark Forkner, noted an “egregious” problem with its MCAS plane system. “I basically lied to the regulators (unknowingly),” Forkner wrote to another pilot. The pilot responded, saying Forkner didn’t “lie” because “no one told us that was the case” regarding the system. According to the Post, one of the employees also said the system was engaging “itself like craxy.” In fatal crashes in Indonesia and Ethiopia crashes—which left a total of 346 people dead—the MCAS system is thought to have pushed the nose of those planes down.

Federal officials said Boeing did not turn over the text messages to the Federal Aviation Administration until Thursday. The agency said it found the texts “concerning” and were “disappointed” that the company “did not bring this document to (FAA) attention immediately upon its discovery.” In a statement, the company said it provided Congress with a document “containing statements by a former Boeing employee” and stated it would “continue to cooperate” with a congressional investigation into the 737 Max. Boeing CEO Dennis Muilenburg is slated to be questioned by Congress later this month.