A new report has emerged, revealing that aircraft manufacturer, Boeing Co, was aware of a fault on its 737 Max models long before the Lion Air and Ethiopian Airlines crashes that claimed the lives of many passengers and crew members.

Boeing‘s engineers are said to have identified a problem with one of the systems on the 737 Max, but chose to ignore it. In 2017, the 737 Max display system software did not correctly meet the AOA Disagree alert requirements. This discovery was made by Boeing engineers after 737 Max deliveries had already begun.

Also note that the alert system was not operable on all airplanes, and Boeing acknowledged this.

Why the alert system is not operable: According to a CNN report, he airlines need to purchase an additional, optional feature, known as the AOA indicator, for the AOA disagree alert to work.

It was reported that 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.

The role of the disagree alert system: While the alert system is not directly linked to the two crashes, the alert system could have played a role in alerting the pilots of both Lion Air and Ethiopian Airlines of any possible malfunctioning from other systems on the plane.

The pilots could have been informed of a sensor malfunctioning, as the preliminary investigations of both crashes suggested faulty data from a malfunctioning angle of attack (AOA) sensor triggered the aircraft’s anti-stall software, known as MCAS, which consequently pitched down the nose of the planes as pilots struggled for control.

The MCAS system was identified as the primary reason for the Ethiopian Airlines‘ crash, although investigations haven’t been concluded.

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Ethiopian Airlines’ crash could have been preventedBoeing said the senior leadership of the company and the Federal Aviation Administration were only aware of the faulty system (MCAS) after the Lion Air crash. Yet, both parties did not intervene in the fleet’s operations until the Ethiopian Airlines crash in March 2019.

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If the level of effort invested after the Ethiopian Airlines crash was the same after the Lion Air crash, perhaps Boeing‘s aircraft would have been grounded worldwide to detect the fault and fix the problem. Unfortunately, both Boeing and FAA didn’t interfere.

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Why Boeing didn’t attend to detected fault: Boeing concluded that the alert function was not necessary for the safe operation of the air-plane. It did not, however, flight-test what would happen to the MCAS system if the single AOA sensor failed.

Boeing‘s engineers didn’t immediately fix the problem, stating that the then functionality of the plane was acceptable until the next planned display system software update.

“The existing functionality was acceptable until the alert and the indicator could be delinked in the next planned display system software update.”

Boeing‘s original software design was criticised by the company’s former engineers and aviation analysts, for relying on data from a single AOA sensor, claiming that those devices are vulnerable to defects.

All 737 Max models will now have an operable alert system, Boeing said, adding that it will also come with an optional angle of attack indicator. While customers with the already delivered 737 Max planes will be able to activate the alert.

“Boeing said it is issuing a display system software update “to implement the AOA Disagree alert as a standard, standalone feature before the MAX returns to service.

“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.

“All customers with previously delivered MAX airplanes will have the ability to activate the AOA Disagree alert.”


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