This sounds like a software bug.

Something like - {copy a to b, checksum a--b}

Instead of - {copy a to t, checksum a--t, copy t to b, checksum a--b}

I bet the fix is along these lines, with the caveat of real time systems/etc.

Taking a grain of salt since it's from a movie, but one of the things about Sully setting the plane down in the river was due to his experience of not just the aircraft itself but also situation awareness to realize he was too low to safely divert to an airport. He instinctually "skipped" several steps in the procedures to engage the APU which turned out to be pretty key. The intimated thing being that the procedure was so long that they might not have gotten to the APU in time going step-by-step.

Unfortunately, sometimes they also fail in ways that even a trained crew isn't able to recover the aircraft. That could be a failure that wasn't anticipated, training that was inadequate, design flaws, the human element, you name it. Actions of the crew being put in an accident report isn't an assignment of blame, it's a statement of facts - the recommendations that come from those facts are all that matters.

There is a design flaw though: the sidesticks in modern Airbus planes are independent, so the other pilot didn’t get any tactile feedback when the second officer was pulling back.

Part of the sales pitch of the Airbus is that the computer does A LOT of handholding for the pilots. In many configurations, including the one that the plane was flying in at the start of the incident, the inputs that caused the crash would have been harmless.

In that incident the airspeed feed was lost to the computer and it literally changed the flight controls and turned off the safety limits, and none of the three people in the cockpit noticed. When an Airbus changes flight control modes, it does not keep inputs idempotent. Something harmless under one set of "laws" could crash the plane under another set of laws. In this case, what the pilot with the working control stick was doing would not have caused a crash, except that the computer had taken off the training wheels without anyone noticing.

As a result of changing the primary controls one pilot was able to unintentionally place the plane in an unrecoverable state without the other pilots even noticing that he was making control inputs.

Tack on that the computer intentionally disregarded the stall warning emanating from the AOA sensor as erroneous at a certain point and did not alert the pilots that the plane was stalled. You are taught from day one of flight training that if you hear the stall alarm you push the power in, and push the nose down until the alarm stops. In this case the stall warning came on, and then as the stall got worse, it turned itself off, with the computer under the mistaken belief that the plane could not actually be that far stalled. So the one alarm that they are trained to respond to in a certain way to recover the plane from a stall was silenced. If I was flying and I heard the stall alarm, then heard it stop, I would assume that I was no longer stalled, not that the plane was so far stalled that the stall alarm was convinced it had broken itself.

So yes, the pilots flew the aircraft into the ground, but the computer suffered a partial failure and then changed how the primary flight controls operated.

Imagine if the brake pedal, steering wheel, and accelerator all started responding to inputs differently when your car had a sensor issue. That causes the cruise control to fail. Add in that the cruise control failure turns off ABS, auto-brakes, lane assist, and stability control for some reason. Oh yeah, there's a steering control on the other side of the car on the armrest and the person sitting there can now make steering inputs, but it won't give feedback in your steering wheel, and also your steering wheel still can be manipulated when the other guy is steering, but it is completely disconnected from the tires while the other guy is steering. All of the controls are also more sensitive now, and allow you to do things that wouldn't have been possible a few seconds ago. Also, its a storm in the middle of the night, so you don't have a good visual reference for speed. So now your car is slipping, at night, in a storm, lights are flashing everywhere, nothing makes sense since the instruments are not reading correctly. However, the car is working exactly as described in the manual. When the car ends up in a ditch, the investigation will find that the cause of the crash was driver error since the car was operating exactly as it was designed.

Worth noting that Boeing (and just about every other aircraft on earth) has linked flight controls between the two pilot's positions that always behave in the exact same way so this type of failure could have never happened on a 737 for example.

At the end of the day, this was pilot error, but more in a "You're holding it wrong, I didn't design it wrong" kind of way. After all, there were three people with a combined 20k flying hours, including thousand of hours in that design.

If three extremely qualified pilots that have literal years of experience in that cockpit, who are rigorously trained and tested on a regular basis for emergencies in that cockpit, can fly the thing into the ground due to a cascade from a single human error... maybe the design of the user interface needs a look.

You also conveniently skipped over the parts of the wikipedia article where they charged the manufacturer with manslaughter, and documented dozens of similar incidents, and the entire section outlining the Human Computer Interface concerns.