Human factors is a combination of aviation medicine, psychology, engineering and ergonomics. It encompasses all of these factors trying to understand the man/machine interface in the aircraft. It has its roots in aviation accident investigations resolving these where no clear technical cause could be found when aircraft became more and more reliable over the years.
As a pilot we need to be alert, healthy and fit so that the flight can be conducted safely. Human fatigue can introduce errors possibly resulting in a disaster.
The FAA has published an Advisory Circular (AC 120-100) regarding pilot fatigue in aviation.
Basics of Aviation Fatigue, 7 June 2010, 30 pages. It is not mandatory or regulation but worthwile to read and learn from.
Excerpt from the document:
This advisory circular (AC): Summarizes the content of the FAA international symposium on fatigue, “Aviation Fatigue Management Symposium: Partnerships for Solutions”, June 17-19, 2008; and describes fundamental concepts of human cognitive fatigue and how it relates to safe performance of duties by employees in the aviation industry.
It also provides information on conditions that contribute to cognitive fatigue; and provides information on how individuals and aviation service providers can reduce fatigue and/or mitigate the effects of fatigue.
To continue reading see the pdf below: