Former Boeing chief 737 technical pilot Mark Forkner asked the US Federal Aviation Administration in 2017 to remove mention of the 737 Max's MCAS system from a report used to develop training standards for 737 Max pilots, according to newly-disclosed emails.
The emails, released by the House Transportation Committee, suggest MCAS was initially mentioned in a draft of a Flight Standardisation Board (FSB) report.
That report, part of the 737 Max's 2017 certification, laid out training requirements for pilots transitioning from the earlier-generation 737NG to the new 737 Max.
The report ultimately did not mention MCAS, the FAA confirms.
"We're starting to work on the reverse differences DT, and I noticed a few things that should be changed… that are in the draft FSB," Forkner wrote to an unknown FAA employee in a 17 January 2017 email.
"Delete MCAS," Forkner writes. "Recall, we decided we weren't going to cover it in the FCOM or the CBT, since it's way outside the normal operating envelope."
"DT" likely refers to the "differences table" contained in the FSB report. That table specifies differences between aircraft and explains corresponding training requirements, says an aircraft technical expert.
FCOM likely refers to the flightcrew operations manual, and CBT is likely shorthand for computer-based training, the expert says.
The House Transportation Committee released 10 pages of Forkner's emails to and from the FAA the same day it released a series of 2017 text messages in which Forkner said he unknowingly lied about the Max's systems to regulators.
The emails include those from the FAA's "Seattle Aircraft Evaluation Group", but names other than Forkner's are redacted.
Information in the tweets sent Boeing's stock sliding and led to questions about how the news might affect the FAA's schedule for clearing the still-grounded 737 Max to fly.
Boeing has said certification will come in the fourth quarter.
The company has been criticised both for its design of MCAS – the software that played a role in two 737 Max crashes – and for not telling airlines or pilots that the system existed.
Boeing 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.
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.
His attorney, David Gerger of Houston law firm Gerger Khalil & Hennessy, did not respond to a request for comment from FlightGlobal.
In another email, on 3 November 2016 to an FAA staffer, Forkner describes 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 writes.
Boeing's stock slipped nearly 7% on 18 October following news of the instant messages.
In those messages, Forkner and another employee, Patrik Gustavsson, talk about MCAS. Forkner says the system was "running rampant in the sim", calling it "egregious".
He adds, "So I basically lied to the regulators (unknowingly)".
Boeing says it is fully co-operating with investigations.
"Over the past several months, Boeing has been voluntarily co-operating with the House Transportation and Infrastructure Committee’s investigation into the 737 Max. As part of that co-operation, today we brought to the committee’s attention a document containing statements by a former Boeing employee," the airframer says of the instant messages. "We will continue to co-operate with the committee as it continues its investigation. And we will continue to follow the direction of the FAA and other global regulators."
The FAA issued a statement calling the "substance of the" instant messages "concerning", and it 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 says.
How the newly-released information will impact the FAA's certification of the Max remains unknown.