You should check with your doc and the airline as well

I travelled on a plane from California to Hawaii. Was 34 weeks going and 35 weeks coming back. I had compression socks, lots of water and made sure to get up often. I was just fine. Definitely impossible to sleep on a plane that far along because there is no way to sleep while crouched over and baby is crammed in my ribs, but other than that no complaints. 

I'm only 8 weeks. So idk if that works the same but I'll be traveling about 9 hours here and back to Minnesota. 

Talk to your doc. I traveled 5 hours by car at 36 weeks. They checked my cervix and just told me to know where a hospital was and "worst case, we can fax your records to another hospital". It's ultimately your decision regardless, but they can give you their opinion/advice. Just be sure you stop and stretch a LOT no matter how you travel.

At 31 weeks I was going to Oklahoma which is 20 hours away and I had to have my cervix checked and an u/s done before I went. I didn't get to go 😔

Def talk to your dr about it, but I know most aren't supposed to travel more than an hour or two away in the third trimester