Boeing Knew of 737 Max Sensor Issue Before Lion Air Crash

By Paul Riegler on 6 May 2019
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A grounded United Airlines Boeing 737 Max jet

A grounded United Airlines Boeing 737 Max jet

Boeing said on Sunday that it knew about an issue with the angle-of-attack disagree alert roughly one year before the deadly Lion Air 737 Max 8 crash in October 2018.

Employees at the company, after determining there was an issue, followed internal protocols and the review determined that addressing the issue could wait until a then upcoming update of the display system software.

“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,” Boeing said.

The disagree alert warns pilots when the sensors were sending conflicting data from angle-of-attack sensors, which read the aircraft’s attitude (the angle of the nose referenced to the direction of the plane’s forward motion). Boeing also said that the AoA indicator and the AoA Disagree alert were not threats to the safety of the aircraft..

“Neither the angle of attack indicator nor the AOA Disagree alert are necessary for the safe operation of the airplane,” it said. “They provide supplemental information only, and have never been considered safety features on commercial jet transport airplanes.”

In the new statement on Sunday, Boeing said that, while employees at the company knew about the issue prior to the Lion Air crash, senior management did not.

Last Monday, Boeing said that its 737 Max aircraft were intended to have the disagree alert as standard cockpit feature.

The alert apparently only worked in those aircraft that also had an optional feature activated, the angle-of-attack indicator, even though it was intended to be a “standard, standalone feature.”

(Photo: Accura Media Group)

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