Software that delivers data from exterior sensors to the flight control system in Boeing 737 Max jets did not meet manufacturer’s requirements, but Boeing never disclosed the problem to U.S. regulators until after the crash of Lion Air flight 610 in Indonesia last October.
The software in question compares data from the two angle of attack (AOA) sensors on Boeing’s 737 Max and delivers a “Disagree” alert if the sensors record conflicting information. A report by The Washington Post found that the AOA disagree alert was inoperable when Southwest Airlines and other carriers started flying the new 737 Max planes.
The AOA sensors, which are prone to damage and malfunction, are at the center of investigations into the crash of Lion Air flight 610 in October and Ethiopian Airlines flight 302 in March. It’s highly probable that a damaged or otherwise faulty sensor fed erroneous data to the aircrafts’ flight controls, sending the planes into anti-stall dives when they weren’t needed.
Pilots of both flights battled the 737 Max flight control system starting just moments after takeoff.
Although the investigations will take some time to complete, the deadly crashes cast a spotlight on potential flaws in Boeing’s Maneuvering Characteristics Augmentation System (MCAS), which the company designed to rely on just one of the aircraft’s two AOA sensors.
Boeing maintains that the disagree alert on its 737 Max jets is nonessential to the safe operation of the plane and that its lack of functionality presents a “low-risk” problem.
“Neither the angle of attack indicator nor the AOA Disagree alert are necessary for the safe operation of the airplane,” according to a statement on Boeing’s website. “They provide supplemental information only, and have never been considered safety features on commercial jet transport airplanes.”
However, evidence from the Lion Air and Ethiopian Airlines crash investigations suggests an operable AOA disagree alert could have at the very least enhanced the safety of the flights by giving the pilots a clearer understanding of the problems they faced. For the most part, pilots remained in the dark about the presence, role, and behavior of the MCAS in the 737 Max’s overall flight control system.
When Boeing first discovered the AOA disagree software problem in 2017, it assigned a panel to review the issue. The committee ultimately determined that the planes were safe to fly despite the software problem. But it wasn’t until more than a year later, after the Lion Air crash, that the company disclosed the issue to regulators at the Federal Aviation Administration (FAA).
According to The Washington Post, it’s unclear if Boeing violated a rule or broke a law by not alerting FAA to the problem in a timely manner, but the matter remains under investigation.
The tragic Indonesian and Ethiopian crashes, which killed 346 people, also call into question the efficacy of the FAA’s oversight and the process by which it certifies new airplane models. How much the agency deferred to Boeing in the review and approval of the 737 Max series remains to be seen.
As for Boeing, mounting evidence suggests that sloppy leadership in recent years coupled with profit-maximizing goals have steered the company into the crisis it finds itself today.