I flew with my RB Milo once. He was in the cabin. It was pretty hard on him, sedated and all. But he did recover. I decided that the long car ride was easier on him, so our return was by car.

As far as the 'under the plane' thing goes, I was never confident with the airlines, that the temperature is maintained. I know that thousands of pets are transported that way, but none of them can tell you how it was. We have to take the word of airline employees.

I'd feel the temp of the carrier by hand and feel the cat right away.

I don't mean to scare you.

Why can't he fly in the cabin?

I'm sure he'll be fine.