An interesting question. I started a thread awhile ago regarding travelling and frags, but it didn't touch upon this.
Much as I love to wear juice, I'd wear little or nothing on a train or plane. IMHO, if your neighbors have the unmitigated audacity to not like the fine scent you're wearing, they are really going to have a lousy time, maybe for 12 hours, and I would feel that I was being quite self-centered to be impinging upon their space.
Just think about how lousy the air quality is on a plane to begin with. It's different in public, where people can get away from you.
I know many will disagree with me, and will just HAVE to wear something. We are addicts, after all.
So please, take it easy on the trigger. Maybe spray on your chest so if you want a snort, you can just move your clothes and get a nice personal waft!
Just think... as soon as you get off that plane, and hit the Big City, that's the time to break out your decant of Exotic Scent and go nuts!!!! My current travel faves are Egoiste and Tam Dao, and these are a bit strong for close plane quarters.
Have a good trip!