Federal prosecutors investigating Boeing are examining whether the company knowingly misled the Federal Aviation Administration while it was seeking the regulator’s approval for its 737 Max plane, according to two people familiar with the matter who spoke on the condition of anonymity to discuss an active inquiry.
In recent months, prosecutors have questioned several Boeing employees in front of a federal grand jury, with some of their queries focusing on whether Mark Forkner, a top pilot at the company, intentionally lied to the regulator about the nature of new flight control software on the jet, the people said. That software, which is known as MCAS and automatically pushes the nose of the plane down, played a role in two crashes that killed 346 people.
The Department of Justice has been investigating Boeing for months, but the information about the grand jury testimony provides some clarity about how prosecutors could be aiming to hold the company accountable for errors that led to the crashes. Mr. Forkner could face criminal charges of lying to the government. The company could also be held liable for potential wrongdoing by Mr. Forkner, because he was a senior employee responsible for Boeing’s interaction with the F.A.A. group that determined the kind of training pilots would need before flying the Max.
Last year, the company made public an instant message chat between Mr. Forkner and his colleague Patrik Gustavsson. In the exchange, from November 2016, months before the F.A.A. certified the Max, Mr. Forkner said MCAS was acting unpredictably in a flight simulator. “I basically lied to the regulators (unknowingly),” Mr. Forkner said.
In grand jury testimony in recent months, prosecutors asked the Boeing employees an array of questions, but kept returning to the issue of whether Mr. Forkner had, in fact, lied to the agency about MCAS.
“We are cooperating with the Justice Department’s investigation,” a Boeing spokesman, Gordon Johndroe, said in a statement.
The Max has been grounded worldwide for nearly a year. The accidents spurred several investigations, including the criminal inquiry led by the Justice Department, and touched off a crisis that has cost the company billions of dollars and upended the global aviation industry.
Boeing fired its chief executive, Dennis A. Muilenburg, late last year and has temporarily shut down production in its 737 factory in Renton, Wash., jolting the national economy and provoking the concern of President Trump. After months of setbacks, Boeing says it has a fix for MCAS and expects regulators around the world to clear the plane to fly by summer.
Prosecutors are trying to determine whether Mr. Forkner knew about a key change that allowed MCAS to trigger in almost all phases of flight and then did not give that information to the F.A.A.
MCAS was designed to activate only when the plane was making sharp turns at high speeds. But late in the development of the Max, Boeing engineers decided they needed MCAS to operate when the plane was flying at low speeds, too. To have the same effect on the plane at low speeds that it had at high speeds, the engineers gave the system more power.
In the messages from November 2016, Mr. Forkner seems to note that MCAS was triggering at low speeds.
“Oh shocker alert!” he wrote. “MCAS is now active down to M .2,” he added, using a technical term that denotes a relatively slow flying speed.
Mr. Forkner’s lawyers, David Gerger and Matt Hennessy, have said their client was reacting to the erratic behavior of a faulty flight simulator and did not mislead regulators.
“Mark didn’t lie to anyone,” they said in a statement. “He did his job honestly, and his communications to the F.A.A. were honest. As a pilot and Air Force vet, he would never jeopardize the safety of other pilots or their passengers. That is what any fair investigation would find.”
Mr. Forkner never told the F.A.A. group in charge of training that a change had been made to the software, The New York Times reported last year. And in emails with F.A.A. officials, he said MCAS would only rarely activate. Two months after his experience in the flight simulator, Mr. Forkner emailed F.A.A. officials to ask that they remove mention of the software from official training materials because, he said, it was so unlikely that it would ever trigger in normal circumstances.
“Delete MCAS,” Mr. Forkner wrote, “since it’s way outside the normal operating envelope.”
Prosecutors are also looking at whether there were broader cultural issues at Boeing that encouraged employees to lie to regulators. In January, the company released more than a hundred pages of internal correspondence in which employees ridiculed the F.A.A. and suggested that they had concealed information from the F.A.A.
In one particularly blunt message from 2018, a Boeing employee wrote, “I still haven’t been forgiven by God for the covering up I did last year.”