Boeing Admits Knowing of Software Issues At Least Year Before First Crash

Canary. Photo by 4028mdk09.

[Updates included below]

According to NPR, a newly released statement from Boeing indicates that “Boeing knew there was a problem with one of the safety features on its 737 Max planes back in 2017 – well before the Lion Air crash in October 2018 and the Ethiopian Airlines crash in March. But it did not disclose the issue to airlines or safety regulators until after the Lion Air plane crashed off the Indonesian coast, killing all 189 aboard.”

Boeing said its engineers discovered a problem with a key safety indicator within months of Boeing delivering the first 737 Max planes to airlines. The indicator, called an angle of attack disagree alert, is designed to warn pilots if the plane’s sensors are transmitting contradictory data about the direction of the plane’s nose.

Boeing maintains in their new statement that their software and sensor warning system “did not adversely impact airplane safety or operation,” asserting that “senior company leadership was not involve in the review and first became aware of issues after the Lion Air crash.”

Air speed, attitude, altitude, vertical speed, heading and engine power settings are the primary parameters the flight crews use to safely operate the airplane in normal flight. Stick shaker and the pitch limit indicator are the primary features used for the operation of the airplane at elevated angles of attack. All recommended pilot actions, checklists, and training are based upon these primary indicators. Neither the angle of attack indicator nor the AOA Disagree alert are necessary for the safe operation of the airplane. They provide supplemental information only, and have never been considered safety features on commercial jet transport airplanes.

The Boeing design requirements for the 737 MAX included the AOA Disagree alert as a standard, standalone feature, in keeping with Boeing’s fundamental design philosophy of retaining commonality with the 737NG. In 2017, within several months after beginning 737 MAX deliveries, engineers at Boeing identified that the 737 MAX display system software did not correctly meet the AOA Disagree alert requirements. The software delivered to Boeing linked the AOA Disagree alert to the AOA indicator, which is an optional feature on the MAX and the NG. Accordingly, the software activated the AOA Disagree alert only if an airline opted for the AOA indicator.

When the discrepancy between the requirements and the software was identified, Boeing followed its standard process for determining the appropriate resolution of such issues. That review, which involved multiple company subject matter experts, determined that the absence of the AOA Disagree alert did not adversely impact airplane safety or operation. Accordingly, the review concluded, the existing functionality was acceptable until the alert and the indicator could be delinked in the next planned display system software update. Senior company leadership was not involved in the review and first became aware of this issue in the aftermath of the Lion Air accident.


Boeing said they alerted the FAA a week after the Lion Air crash on November 6, 2018 and that they had issued an ‘Operations Manuel Bulletin” (OMB), adding that is was a day later the FAA issued a “Airworthiness Directive (AD).”

According to the FAA’s website, ADs are defined as “legally enforceable rules issued by the FAA in accordance with 14 CFR part 39 to correct an unsafe condition in a product. 14 CFR part 39 defines a product as an aircraft, aircraft engine, propeller, or appliance.”

According to CNN reporting, “the AOA disagree alert only worked on an aircraft if the airline had purchased an additional, optional feature, known as the AOA indicator, Boeing said.”

The AOA indicator lets pilots know if one of the AOA sensors is not working, while the disagree alert shows if the sensors contradict each other.

Boeing contends the alert function was not necessary for the safe operation of the airplane. But former Boeing engineers and aviation analysts interviewed by CNN criticized Boeing’s original software design for relying on data from a single AOA sensor, claiming that those devices are vulnerable to defects.

Boeing also did not flight test what would happen to the MCAS system if the single AOA sensor failed, CNN previously reported.

Watch: An April 30 CNN investigation of the Boeing 737 Max aircraft uncovers a “history of issues with one component being blamed for two deadly crashes. Boeing insists nothing is wrong with the design, blaming pilots for not following proper procedure.”

Yahoo Finance discusses “what Boeing may have known about regarding the software issue that may be linked to 737 Max 8 plane crashes.”

In Boeing’s rush to get the Max out to compete with Airbus’ new model, the New York Times reported, “In addition to a two-hour iPad course from Boeing” which was then “used to create a 13-page handbook of the differences between the Max and its predecessor.”

Is it ‘just a computer bug,’ or is this really a scandal and cover up about who knew what and when.

Published 15 April 2019

Watch 60 Minutes Australia: Rogue Boeing 737 Max planes ‘with minds of their own.’

Updates 1:

Boeing did not adequately label two key toggle switches that could have disabled the Maneuvering Characteristics Augmentation System (MCAS) in its 737 Max aircraft, according to the Seattle Times in an exclusive report. The MCAS is suspected of causing both the fatal crashes of the Lion Air and Ethiopian Airlines flights, killing 346 people. The change occurred when Boeing was moving from its 737 NG model to the 737 Max, according to the paper, which reviewed flight manual documents. In the new 737 Max cockpit, the switches “became more restrictive.” Boeing declined to comment for the Seattle Times report. Former Boeing engineer Peter Lemme first raised the issue with the new design in a blog in which he questioned why Boeing would “abandon the old setup.”

For further read, see: Seattle Times

Update 2:

CBS obtains audio of American Airlines pilots confronting Boeing official after first Max fatal crash.

For further reading: When the Pentagon’s Door Revolves: “Brass Parachutes”

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