Do you think a 90 year old person could take a very long flight first class?

I am leaving and my dad is 90. Keeps bouncing back from injuries and illnesses. When I move back to Australia, no one will be able to care for him like I do. I am considering flying him over first class and just taking care of him there. My sister here will say I am crazy but no one here has time for him. Think it’s possible?