Flight crew fatigue (Part 121)

[TurboS7]

That is why we formed an in house union and one of the work rules is that we will not fly more than a 16 hour day. Some days a 16 hour day can be no problem, other days it can be disaster depending really on you sleep and scedule 48 hours prior. That is where fatigue is dangerous, you cannot define it, higher stress level(kids, job, home, finance) the greater the fatigue.