It is technically legal. However, you are not allowed to use it while on the plane. It is important to know that while you know the vape is legal, law enforcement might not see it that way, which would cause problems. You must have the batteries on carry on, it is not allowed in checked baggage, this goes for all vapes, not just hemp ones.Also, remember that this is going by U.S. Federal law, most foreign countries have much lower THC limits, if at all. Make sure you know the laws of the place you are going too, including local American ones. For example, bringing what the U.S. classifies as hemp to a country such as Russia would be considered trafficking, a serious crime in most countries.