Why is fatigue considered as one of the most treacherous hazards to flight safety?

Fatigue is a state of reduced alertness and decreased performance. It can be caused by a number of factors, including lack of sleep, irregular sleep schedules, and stress.
Fatigue can impair a pilot's ability to make decisions, react to emergencies, and maintain control of the aircraft. This can lead to a number of serious safety hazards, including collisions, runway overruns, and controlled flight into terrain (CFIT).
The problem with fatigue is that it can be difficult to detect. Pilots may not realize that they are fatigued, even when they are making mistakes. This is because fatigue can impair judgment and cognitive function.
As a result, fatigue can be a silent killer. Pilots may not realize that they are making mistakes until it is too late.