I think if your dog gets excited and poops all over the airport you need to somehow decondition her to situations like that. Try taking her into Petco,Home Depot, and any other stores where dogs are allowed on a routine basis. I wouldn't feed her past supper time day before flight, and give her an enema outside ( because she will poo immediately ) morning of flight.
https://www.amazon.com/Pet-Ema-Enema-Dogs-Cats-250/dp/B001BBXD9C?tag=canigivemydog-desktop-20&linkCode=ptl&linkId=0af64891cbde54d3ba6a332f991e5988
If she is so anxious that she is shaking during flight ask your vet to prescribe generic Xanax (Alprazolam) at the dose of 0.02-0.1 mg/kg orally two-four times per day.