How faulty Boeing system eventually led to 737 MAX crashes

The Boeing MCAS system was found to be ineffective in its function and the way it was implemented. Jon Ostrower, editor-in-chief of The Air Current, joined KIRO Nights to discuss the nature of the MCAS system and its issues.

“So in a nutshell, MCAS was determined to be needed by Boeing. It’s called the Maneuvering Characteristics Augmentation System. It’s a mouthful, but the overall design of it is to make the airplane handle in the hands of the pilots the same way as the 737 NG that preceded it,” he said.

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“So what happened was that when Boeing was in the wind tunnel and doing analysis on the initial design of the MAX with its bigger engines that’s a little bit farther forward, they found that they would need some type of additional pilot nudge with the horizontal stabilizer in the back of the airplane to help the airplane … recover from a stall the same way as a 737 NG. And it’s entirely transparent to the pilot.”

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The system functioned erroneously, which is ultimately what led to the crashes. The 737 MAX was grounded worldwide for more than 20 months after two deadly international crashes. Those two crashes led to the deaths of 346 passengers and crew between Lion Air Flight 610 in late 2018, and Ethiopian Airlines Flight 302 in early 2019.

“That kicked off design effort over the years leading up to the 2016 first flight of the airplane, where they essentially programmed the system to rely on a single sensor for activation,” Ostrower described. “And it was expanded actually in flight tests when they found that it was this type of upward nudging that came along with the airplane. … In 2016, they expanded the system and tied it to a single angle of attack sensor to activate. Problem is, in the case of Lion Air 610 and Ethiopian 302, those systems activated erroneously causing the airplane to get significantly out of trim.”

“Which ultimately caused the crews — for many number of reasons that very much related to how they interact with systems and what they knew at the time — caused them to lose control in both fights that crashed in 2018 and 2019,” he added. “That ultimately resulted in the grounding that we had for 20 months on the MAX program.”

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