I've carried both a monopod and a tripod on board on an aircraft a number of times... (In Australia, SE Asia and Europe).. I've never had an issue, i assume if you took it without cameras you would seem a bit suspicious haha. But i personally havent had any problems.
I tend to agree with CR guy though when he says he checks it in... on a recent Indian project I had to travel with a couple of tripods, i simple got a big role of bubblewrap and wrapped it around it, wrapped gaffa around that, and put a fragile sticker on it. Simple, cheap and means your don't have to squeeze it into your suitcases/bags.
Just make sure you insure it if it's a pricey one