Instant messages between two high-level Boeing employees in 2016 indicate that the company was aware of major problems with an automated feature on the 737 Max jet that has been implicated in two deadly crashes.

The messages, between two top pilots, were about an automated feature known as the Maneuvering Characteristics Augmentation System (MCAS) that investigators say repeatedly — and in error — forced down the noses of planes that crashed in Indonesia and Ethiopia, killing 346 people.

In the messages, Mark Forkner, then chief technical pilot for Boeing's 737, wrote to technical pilot Patrik Gustavsson that the MCAS was engaging "itself like craxy [sic]," calling the problem "egregious."

Forkner, who had a major role in the Max, also indicated that the Boeing employees misled the Federal Aviation Administration. "So I basically lied to the regulators (unknowingly)," he wrote.

"It wasn't a lie, no one told us that was the case," Gustavsson replied.

The messages show the company experts had identified critical safety concerns with the Max years ago, even as Boeing executives have publicly argued since the crashes on Oct. 29 and March 10 that the company had followed the same internal practices and FAA certification procedures that have long produced safe airplanes.

Boeing did not turn the messages over to the Department of Transportation until Thursday, federal officials said. The document "containing statements by a former Boeing employee" was given to Congress on Friday, Boeing said in a statement.

In a letter to Boeing CEO Dennis Muilenburg on Friday, FAA administrator Stephen Dickson said: "I expect your explanation immediately."

The FAA said in a statement that it "finds the substance of the document concerning. The FAA is also disappointed that Boeing did not bring this document to our attention immediately upon its discovery."

The flurry of messages between the pilots came over a 10-minute stretch in 2016 as the company was working with the FAA to obtain the safety certification needed to sell the Max in the United States and around the world. The new plane was critical to Boeing's plans to compete with rival Airbus. The FAA granted Boeing the coveted certification in March 2017.

A copy of the message chain was given to the Department of Justice in February in connection with the criminal probe into the Max, according to Richard Cullen, an attorney at McGuire Woods representing Boeing.

Cullen said the document was produced properly and in a timely fashion "to the appropriate agency."

Boeing said it "will continue to cooperate" with an investigation by the House Committee on Transportation and Infrastructure and "we will continue to follow the direction of the FAA and other global regulators, as we work to safely return the 737 Max to service."

In a call to Dickson Friday, Muilenburg told the administrator that the company is "taking every step possible to safely return the Max" to the air, Boeing said.

Forkner moved to Southwest Airlines last year. Gustavsson was promoted to Boeing's 737 chief technical pilot in 2018, according to a LinkedIn listing. Boeing did not answer a question about Gustavsson's current role.

The existence of the messages was first reported by Reuters.

Rep. Peter DeFazio, chairman of the House Transportation Committee, said the "outrageous" message chain showed "Boeing withheld damning information from the FAA."

"This exchange is shocking, but disturbingly consistent with what we've seen so far in our ongoing investigation," DeFazio, D-Ore., said, pointing to "a lack of candor with regulators and customers."

"This is not about one employee; this is about a failure of a safety culture at Boeing in which undue pressure is placed on employees to meet deadlines and ensure profitability at the expense of safety," DeFazio said.

Forkner set the tone early, writing: "I'm locked in my hotel room with an ice cold grey goose, I'll probably fire off a few dozen inappropriate emails before I call it a night."

Gustavsson asked if Forkner had accomplished anything in the flight simulator, "Or what is the normal chaos there?"

Forkner joked about what would happen if they no longer worked together, and said if Gustavsson left Boeing "I'd ask for a job in sales where I can just get paid to drink with customers and lie about how awesome our airplanes are."

The MCAS feature was "running rampant" in the simulator, Forkner wrote.

MCAS was supposed to compensate for design changes and help make the 737 Max feel the same in the air for pilots used to earlier models of the 737. It would achieve that by automatically adjusting the way the plane was flying by moving the horizontal stabilizer on the plane's tail. The stabilizer makes the aircraft ascend or descend.

The National Transportation Safety Board last month described how in the run-up to the Oct. 29 crash in Indonesia, MCAS automatically pushed the plane's nose down "more than 20 times" in a 6-minute stretch before it plunged into the Java Sea. Investigators say faulty data from a sensor caused the feature, which had been made increasingly powerful over the course of the airplane's development, to repeatedly misfire.

In the message chain, the technical pilots talked about how the plane, in more than one simulated scenario, was aggressively adjusting how much it was heading either up or down, a process known as "trimming." Pilots often do that manually, but MCAS does it automatically in certain cases.

The 737 Max has been grounded since March, shortly after the second crash in Ethiopia. Boeing has been working on a software fix for the MCAS and other problems discovered as part of the recertification process.

It is unclear when the plane will be cleared by the FAA to resume service.