Boeing knew about missing alarm a year before first crash

Boeing knew about missing alarm a year before first crash

Boeing knew months before a deadly 737 Max crash that a cockpit alert wasn't working the way the company had told buyers of the single-aisle airliner. It was created to warn pilots about the kind of sensor malfunction that occurred in the crash in Indonesia and another five months later in Ethiopia. When the MAX returns to service, all MAX production aircraft will have an activated and operable AOA Disagree alert and an optional angle of attack indicator.

But only 20% of customers had purchased the optional feature, and neither Lion Air nor Ethiopian Airlines had functioning angle of attack disagree indicators on their 737 Max fleets, The New York Times reports.

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 said the 737 MAX's "display system software did not correctly meet the AOA Disagree alert requirements", adding that "software delivered to Boeing linked the AOA Disagree alert to the AOA indicator, which is an optional feature on the MAX" and earlier versions of the 737.

In manuals that Boeing gave to Southwest Airlines, the biggest operator of both the Max and 737s in general, the warning light was depicted as a standard feature just as it is on older 737s, according to Southwest spokeswoman Brandy King.

A review into the pilot warning system glitch had concluded that "existing functionality was acceptable" until a planned software update.

Boeing says its senior leadership wasn't aware of the problem until after the Lion Air crash.

American Airlines pilots submitted written comments to the FAA about their concern that Boeing is not taking adequate steps in new draft training proposals for the 737 MAX. However, Boeing's timely or earlier communication with the operators would have helped to reduce or eliminate possible confusion. At the same time, the company is now working on a software update to tame the over-eager MCAS system.

Ultimately, the company decided that the problem was not severe enough to merit action, and that it "did not adversely impact airplane safety or operation".

Boeing discussed the status of the AOA Disagree alert with the FAA in the wake of the Lion Air accident.

But the new jets were already being delivered, and U.S. regulators were not immediately told as Boeing did not believe the apparent mistake posed any risk.

The sensors malfunctioned during an October flight in Indonesia and another in March in Ethiopia, causing software on the planes to push their noses down. This system automatically pitched the plane downwards to prevent stalls, an unfortunate byproduct of the 737 MAX's aerodynamic design and high-mounted engines.

The panel determined the issue to be "low risk", and said Boeing would have to fix it as part of an overall package of enhancements to the Max in response to the Lion Air accident.

Boeing has admitted it knew about a missing feature on its 737 Max plans a year before the first of two fatal crashes.

"That's negligence from Boeing in regards the AOA system", said Evi Samsul Komar, whose son and nephew were on the fatal flight.

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