> The captain was on a break when the co-pilots became confused by faulty air-speed readings. They then mistakenly pointed the nose of the plane upwards when it stalled, instead of down.
Investigators concluded the co-pilots did not have the training to deal with the situation
You allude to the difference between requirements and constraints. What you say is true, but also it's true that the Therac-25 was not designed to not output high power when an operator typed quickly.