Anti-stall System Examined As Factor In Boeing 737 Max Crashes

Investigations have pinpointed an anti-stall system installed in Boeing 737 Max aircraft as a potential factor in the crashes of two of the jets in the past five months. In both the March crash in Ethiopia and an earlier one in Indonesia, authorities suspect that faulty sensor data triggered the anti-stall system, contributing to the aircrafts’ failure. All of the Max aircraft in the world are believed to have now been grounded.

According to sources familiar with the matter, Boeing Co. (NYSE: BA) decided to make two significant changes to an automated anti-stall system after the Federal Aviation Administration’s (FAA) initial safety review. The software, known as MCAS, was initially programmed to move the stabilizer of the jet about 0.6 degrees in about 10 seconds in a limited number of situations. The changes bumped that up to 2.5 degrees in less than 10 seconds under a broader array of circumstances.

The FAA did not conduct another safety review of the anti-stall system after the changes were made. Instead of a new review, the agency relied on an earlier assessment of the system. According to the agency’s rules, an additional review is only required if the changes affect how the plane operates in riskier phases of flight. A spokesman for the agency said, “The change to MCAS didn’t trigger an additional safety assessment because it did not affect the most critical phase of flight, considered to be higher cruise speeds.”

While the FAA has a reputation as the gold standard in global aviation regulation, the omission involving Boeing’s 737 Max exposes a glaring regulatory gap. The agency has defended its certification process, saying it has consistently produced safe aircraft. Regarding the 737 Max aircraft, the agency says that it spent more than 110,000 hours reviewing the jets, including 297 test flights.

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