renzeroThis is true, they will always leave behind a residual smell and if it catches the nose of a flight attendent or nervous passenger, they will be tossed. If it happens before you're in the air, probably no problem. Who knows what they'd say if they realized in flight. I had 2 coming back from a trip to Utah skiing, had to toss 1 but managed to keep the other.
That said, in terms of effectiveness, I love these things. Lasts all day on the mountain, gets to a good temperature... lot to manage with the fluid but you get used to it. I am probably too cheap to increase the price point of these by replacing my confiscated one, but I'm sure I'll be using the lone survivor to walk my dog this winter.
je11yThe purpose of my review was the emphasize that it was empty and not used in days, and still left a residual smell that caused it to not be able to fly. It is not something you can take with you both ways for cold weather travel reliably.