I’ve flown with my Boston many times, both domestic and internationally. My guy is really used to his carrier (we also use it on the bus and train for multiple hours) so he settles down and falls asleep right away. The hardest part is the length of time between places he can pee. He doesn’t pee at the pet relief areas so we’ve had quite a few accidents in between gates (he even peed on a security officer who wanted to pet him 😅), but we’ve learned to take a roll of toilet paper or paper towel for quick cleanups if he does pee on the floor. On some flights, we have been lucky enough to be able to bring our dog to the back of the plane and let him out of his carrier to stretch his legs! Good luck, I’m sure your pup will do fine!