So Boeing produced a dynamically unstable airframe, the 737 Max. That is big strike No. 1. Boeing then tried to mask the 737 dynamic instability with a software system. Big strike No. 2. Finally, the software relied on systems known for their propensity to fail angle-of-attack indicators and did not appear to include even rudimentary provisions to cross-check the outputs of the angle-of-attack sensor against other sensors.