Sasha is GREAT in the car and a mess on an airplane.
We fly to Florida from NY every month during the winter.
When I first brought her home from Bonnie Palmer at 12 weeks she was great, but one month later and after that she was not happy.
We gave her benedryl (with my vets advise) and it didn't help her at all.
We give her now a bit of valium and she is better on the plane. She still doesn't sleep, but she is more relaxed. I keep her bag on my lap after take off and until landing and this helps her too.
If anyone has better suggestions, I will be very happy to hear some advise, because as soon as it get cold here in NY we will back and forth to Florida.