I have been following this thread and I am amazed that there is still so much discussion about the problems on a Plane, why ? . I know the OP has the best of intentions but look at the alternatives, the plane idea seems totally unrealistic.
I am pleased that @Sheryl has joined in with her sensible comments especially regarding care in Thailand. As I said before Thailand has been promoted as a perfect place for aged care as the cost is usually less than The Australian age pension.
The number of elderly Parents consigned to the aged care industry in Australia is very sad , nobody seems to want Granny or Granddad any more, they would rather pay or spend their inheritance and visit occasionally .
Regarding costs , if he has sold a property he must have some funds and I would assume he receives some sort of pension so Thai care accommodation should be well within his reach, why send him back to the unknown.
I am from the UK originally via fifty years in Australia, soon to be eighty and luckily married to a Thai Lady who I am sure will look after me until the day I end up in the fire, I'm lucky......