The crew is an extremely fragile system whose level of performance, the ability to respond efficiently to a given situation depends on the quality of the environment in which it operates.
In aviation, some events may be described as “catastrophic” and are therefore recoverable with difficulty by the crew, engine explosion for example, others are more “simple” and therefore easily detected and corrected by an efficient crew (misreading a checklist or error handling of a device for example)
If the crew is under pressure, tired or weakened by the environment in which it operates, its performance may make it unable to cope with an event called “simple”.
So, what was the quality of the environment in which the crew was operating?