It's likely a (deliberate) training fault on the part of Boeing here. The new engines+nacelles change the handling characteristics of the aircraft and add a su

It's likely a (deliberate) training fault on the part of Boeing here. The new engines+nacelles change the handling characteristics of the aircraft and add a substantial pitch-up characteristic. Boeing wanted to brand this as a drop-in replacement for your existing 737 fleet requiring no additional re-training beyond normal ongoing certifications, so they added new systems to address this flight characteristic, and neglected to document this in their flight manuals or any of their training materials. The system activated erroneously in-flight and the pilots could not cancel a system they did not know existed. https://www.seattletimes.com/business/boeing-aerospace/u-s-pilots-flying-737-max-werent-told-about-new-automatic-systems-change-linked-to-lion-air-crash/ https://www.seattletimes.com/business/boeing-aerospace/u-s-p... https://outline.com/t78kad https://outline.com/t78kad https://youtu.be/zfQW0upkVus?t=220 https://youtu.be/zfQW0upkVus?t=220 There are other contributing factors here, there are apparently multiple failure conditions that can activate this system without appropriate degrees of redundancy (which is a design fault and will probably be rectified at some point), but the primary cause here is that Boeing suppressed information about this system's existence in an attempt to make their new aircraft more attractive compared to Airbus's alternatives. The aircraft itself is not faulty in the sense that it cannot be controlled when these failure conditions occur. Boeing was negligent in its training and marketing of these aircraft.