As reported by engadget,
Instead, it built a software system — Maneuvering Characteristic Augmentation System (MCAS) — which would automatically kick in to avoid these stalls. MCAS malfunctioned, however, which led to two fatal crashes: Lion Air Flight 610, and Ethiopian Airlines Flight 302. A subsequent investigation found that Boeing employees had raised major concerns about the system’s design and operation. And the FAA added that it had failed in its oversight when originally certifying the plane as safe.
After the crashes, the 737 Max was grounded, with Boeing spending the following 18 months working to fix its problems. This process has turned up a number of additional bugs within the system which have needed their own time to fix, further delaying its return. The FAA re-certified the plane in November (regulators in Europe did the same in October) and American quickly ran a test flight — with the media on board — at the start of December. The airline has affirmed that passengers who do not wish to fly on a 737 Max will be offered “flexible rebooking.”
A number of other airlines expect to return the 737 Max to the skies through 2021, with United Airlines planning to resume service in February. Southwest Airlines, meanwhile, say it’ll resume at some point in the second quarter of 2021, so at least by June. It remains to be seen, however, if a plane that has been held up as an example of how Boeing’s culture has failed, and as a broader calamity, will be able to win over a suspicious public.