You have to preregister, and there is a limit on animals per flight- so don't dawdle. You also have to have a recent clean bill of health from a vet. The fee is between $50 and $100, and the puss can sit under the seat in front of you provided you have a suitable carrier. EZE is a ~10 hour flight, so Felix might wet his knickers, but I would rather have the beast where I can see him than in the hold. Good luck.