Boeing says instant text messages between company pilots suggesting that it may have had prior understanding of the flaws in its Maneuvering Characteristics Augmentation System (MCAS) on 737 Max aircraft have been misinterpreted, and it was “unfortunate” that they were released without “meaningful explanation”.
The MCAS has been implicated in two fatal crashes: the first in Indonesia in October 2018 and the second in Ethiopia less than five months later, killing a total of 346 people, and leading to the grounding of all 737 Max aircraft worldwide in March 2019.
The revelation of the text messages between former technical pilot Mark Forkner and another employee Patrik Gustavsson on Friday caused Boeing stock to fall 8%, and created yet further uncertainty in the almost year-long 737 Max saga. It is unclear how these developments will affect the FAA's schedule for clearing the still-grounded aircraft to fly.
“While we have not been able to speak to Mr. Forkner directly about his understanding of the document, he has stated through his attorney that his comments reflected a reaction to a simulator program that was not functioning properly, and that was still undergoing testing,” Boeing says in a statement on 20 October.
“We are continuing to investigate the circumstances of this exchange, and are committed to identifying all the available facts relating to it, and to sharing those facts with the appropriate investigating and regulatory authorities.”
Boeing had previously said certification will come in the fourth quarter but industry experts consider this an optimistic timeline. Several airlines, including Southwest – which operates the largest 737 fleet – and Air Canada, have taken the aircraft out of their schedules through mid-February. Boeing has been criticised both for its design of MCAS and for not telling airlines or pilots that the system existed.
The airframer has maintained MCAS is designed to operate in extreme flight conditions, such as when the aircraft is an unusual angle-of-attack. It has said an MCAS failure would resemble a "runaway stabiliser" event, which pilots could counter by following established procedures.
The planemaker handed over the instant messages about the MCAS system to the Federal Aviation Administration earlier this week. In the messages, Forkner, the 737 Max's chief technical pilot at the time, told another Boeing pilot that the MCAS is "running rampant in the sim" – referring to the flight simulator – and that the system's performance was "egregious".
He added: "So I basically lied to the regulators (unknowingly)".
Forkner was Boeing's chief 737 technical pilot from October 2011 to July 2018, according to his LinkedIn profile, and now works at Southwest Airlines.
The FAA issued a statement calling the "substance of the" instant messages "concerning", and fired off a letter to Boeing chief executive Dennis Muilenburg, asking for explanation.
"Boeing President and CEO Dennis Muilenburg called FAA Administrator Dickson to respond to the concerns raised in his letter. In addition, Mr Muilenburg assured the administrator that we are taking every step possible to safely return the Max to service," Boeing said.
In Sunday's statement, Boeing says the messages refer to simulator software that had not been finalised rather than failures of the MCAS.
"The simulator software used during the Nov. 15 session was still undergoing testing and qualification and had not been finalised, but it, too, provided for MCAS operation at low speed," Boeing says. "Separately, a low-speed version of MCAS was installed on the airplanes used for training-related flight testing that the FAA administered in August 2016. And FAA personnel also observed the operation of MCAS in its low-speed configuration during certification flight testing, beginning in August 2016 and continuing through January 2017."
On Friday, further emails from 2016 and 2017 released by the House Transportation Committee show that Forkner asked the US Federal Aviation Administration to remove mention of the 737 Max's MCAS system from a report used to develop training standards for 737 Max pilots. The report ultimately did not mention MCAS, the FAA said.
In an email to an FAA staffer on 3 November 2016, Forkner described his effort to convince overseas regulators to certify the Max as "Jedi mind tricking".
"I'm doing a bunch of travelling… simulator validations, Jedi-mind tricking regulators into accepting the training that I got accepted by the FAA," Forkner wrote.
Boeing says in its statement on Sunday, "We understand entirely the scrutiny this matter is receiving, and are committed to working with investigative authorities and the U.S. Congress as they continue their investigations." It adds it is “committed to continuing to work closely with the FAA and global regulators to ensure the MAX’s safe return to service.”
Boeing chief executive Denis Muilenburg, who was stripped of the company’s chairmanship earlier this month, is scheduled to testify before the House Transportation Committee on 30 October about MCAS and the 737 Max.