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Boeing Failed To Disclose 737 Max Issue For More Than A Year

Boeing did not tell US regulators for more than a year that it inadvertently made an alarm alerting pilots to a mismatch of flight data optional on the 737 Max.

The US plane maker has been trying for weeks to dispel suggestions that it made airlines pay for safety features, after it emerged that an alert designed to show discrepancies in "angle of attack" readings from two sensors was optional on the 737 Max.

Erroneous data from a sensor responsible for measuring the angle at which the wing slices through the air -- known as the angle of attack (AOA) -- is suspected of triggering a flawed piece of software that pushed the plane downward in two recent crashes.

boeing 737 max
A Boeing 737 Max in flight. Photo: Getty.

In a statement, Boeing said it only discovered once deliveries of the 737 Max had begun in 2017 that the so-called AOA Disagree alert was optional instead of standard as it had intended, but added that was not critical safety data.

A Federal Aviation Administration official told Reuters on Sunday that Boeing waited 13 months before informing the agency in November 2018.

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By becoming optional, the alert had been treated in the same way as a separate indicator showing raw AOA data, which is seldom used by commercial pilots and had been an add-on for years.

"Neither the angle of attack indicator nor the AOA Disagree alert are necessary for the safe operation of the airplane," Boeing said.

boeing max 737 Ethiopian Transport Minister Dagmawit Moges
Ethiopian Transport Minister Dagmawit Moges speaks during a press conference on 'Boeing 737 Max 8' crash in Addis Ababa. Photo: Getty.

"They provide supplemental information only, and have never been considered safety features on commercial jet transport airplanes."

Boeing said a Safety Review Board convened after a fatal Lion Air crash in Indonesia last October corroborated its prior conclusion that the alert was not necessary for the safe operation of commercial aircraft and could safely be tackled in a future system update.

The FAA backed that assessment but criticised Boeing for being slow to disclose the problem.