FAR pt117
Cargo pilots don't get fatigued. The US government say so.
Call in fatigued:
Scheduler can't wont help
You must speak with the DO
Expect a lengthy repetitive interrogation
This is recorded on the DO LOG
Your Fleet Capt will read this
Then they will call you as if they knew nothing, again expect interrogation
The incident will be recorded on your internal file.
So they know exactly how many times you called in sick, fatigued,etc.