By Michael Hernandez
WASHINGTON (AA) - U.S. aerospace giant Boeing withheld "concerning" information about the safety of its 737 Max aircraft, the Federal Aviation Administration, or FAA, said Friday.
Boeing had "alerted" the Department of Transportation on Thursday to instant messages between two employees that characterized "communications with the FAA during the original certification of the 737 MAX in 2016," the agency said in a statement.
The FAA said it discovered the communications "months ago” and is "disappointed that Boeing did not bring this document to our attention immediately upon its discovery."
"The FAA is reviewing this information to determine what action is appropriate," it said.
Agency administrator Steve Dickson wrote a terse letter to Boeing President Dennis Muilenburg published on the FAA's website demanding an immediate explanation "regarding the content of this document and Boeing's delay in disclosing the document to its safety regulator."
The FAA nor Boeing disclosed what was in the instant messages, but multiple media reports said they centered around a test pilot saying a flight-control system, known as MCAS, was difficult to control.
That software system has been at the center of attention following two devastating crashes that have led to the 737 Max being grounded since March.
The pilot said, in messages published by CNN, that the MCAS system was "running rampant" during simulator testing, and that it has "some real fundamental issues that they claim they're aware of." It is unclear who is referring to in the conversation.
"I basically lied to the regulators (unknowingly)," the employee wrote.
His colleague responded: "It wasnt a lie, no one told us that was the case."
In all, 346 people were killed in the two crashes.