I think the answer has already been given for the most part: it's ok to take your pv with you on planes.
I'll share my experiences.
-in 2010, while passing through security in a Canadian airport, on my way to the US, they spotted the
hex copper mod in my back pack carry on and forced me to check it in. From what I understood, if it was a more elegant looking pv, they would have let it through (the copper hex looks like a pipe bomb). I also gave the year because I think with time everyone is getting more used to them and its becoming less of an issue. I would bet that if you went with a hex copper today to the same airport you'd be ok.
This mod attracted attention in a few other airports but after I explained, they were ok with it.
-Just recently on several other international and domestic flights I brought my "less dangerous looking" roughstack. I always put it in my backpack when going through security (why show it to anyone unless they spot it) along with a few spare batteries and cartos, and they let my backpack through without any questions.
-also I vaped on the plane with no issues. In my seat, I simply inhale deeper and hold the vapor longer than blow towards my lap and haven't had any issues. Also in the plane toilette, I vaped quite liberally and blew the vapor towards the floor with no problems ( I was too chicken to blow the vapor towards the smoke detector to test what happens)
vape on.