The phrase human error can end an investigation before anyone asks why the error was easy to make.

Human error is where investigations stop when they could go further. Naming the person who made the mistake answers who, and it forecloses the more useful question of why the mistake was available to make: the confusing layout, the fatigue, the two controls that look identical. Blame is a satisfying endpoint and a poor explanation.

When something goes wrong, on any scale, push past the person to the conditions. Ask what made the error easy, and whether anyone else would have made it. This is not about excusing people. It is that fixing conditions prevents recurrence and blaming individuals almost never does.