I'm sorry that your conversation didn't go well. I think I remember that you normally get along well with your dad?
Hopefully a brief break will do the trick, and things will be back to normal

I wonder why he has so much anger? Is it new? Does your sister have any ideas as to why he is so angry?

I'm sure it will be hard for your father to see his sister now, and it will be a difficult trip for him.
Does he have any sx of dementia himself? If he does, and he is aware of them, that may explain some of the anger...