NTSB Announces Detailed Critique of Ethiopia Max 8 Crash Results

[ad_1]

Photo: Boeing

Nearly a month after posting comments criticizing the Ethiopian Aviation Accidents Investigation Bureau (EAIB) for its final report into the fatal crash of a Boeing 737 Max 8 in March 2019, the National Transportation Safety Board (NTSB) of the United States released new comments today (January 24) challenging the Ethiopians. Today’s comments offer details implicating the EAIB’s conclusion as to the source of the faulty angle of attack data and insufficient attention to the human performance aspects of the accident.

While the December 27, 2022 Boards Statement acknowledged the role of the Max 8’s much-criticized Maneuvering Characteristics Augmentation System (MCAS) in the crash that killed all passengers aboard Flight 302 d ‘Ethiopian Airlines shortly after takeoff, the NTSB now claims the EAIB report unfairly blamed the manufacturer for electrical issues that caused erroneous angle of attack output.

Today’s statement from the NTSB indicates, in part, that the EAIB wrote electrical anomalies that had existed since the production days of the crashed planes [italics added] caused the AOA sensor heater to fail, causing the AOA sensor to provide erroneous values ​​that caused MCAS to repeatedly pitch the aircraft’s nose down until it hit the ground.

But the NTSB discovered that the erroneous output of the AOA sensor was caused by the separation of the AOA sensor vane due to impact with a foreign object. [italics added], which was probably a bird. During the accident investigation, the NTSB provided the EAIB with evidence to support this conclusion, but this evidence was not included in the final report.

The board further wrote: The function of AOA sensor blade heaters is to prevent the formation of ice which could restrict the movement of the blades. The conditions present at the time of the accident were above freezing temperatures with no moisture present (i.e. ice could not form regardless of the operational state of the heaters). Thus, a loss of electrical current through the vane heater at any time during the accident flight would not explain the event as the loss of electrical current would have had no effect on the output of the AOA sensor.

The NTSB also cited as misleading the EAIB’s findings on Boeings alleging a lack of documentation for flight crews regarding the correct procedures in the event of a sensor failure causing the MCAS system to induce pilot flight commands. automatic nose-down. Boeing had provided the information to all 737 Max operators four months before the Ethiopian Airlines crash, according to the NTSB statement released today.

[ad_2]