Many times there are authorities that have formalized protocols for systems involving people. For example, the FAA has prescribed thresholds where pilots should

Many times there are authorities that have formalized protocols for systems involving people. For example, the FAA has prescribed thresholds where pilots should be alerted of possible failures when navigation system measurements have exceeded those thresholds. Other times thresholds like those can be found just through user testing and feedback. The goal there is to ensure safety without losing the confidence of the user or overwhelming them with information. There are a number of general Software Assurance protocols. I'm not super familiar with them, but DO-178C is one I hear about often which is a process specifically for assuring/certifying airborne systems.