Never had a problem carrying a tripod on board pre- or post-9/11 but that was before the crackdown on carry-on bags.
Since around 2009, speaking only from personal experience, airlines have been much stickier about what's allowed on carry-on. Even if it fits the size requirement, I've been denied. Baggage fees have become a BIG revenue generator for airlines in the last 2-3 years so they're doing everything they can to force you to pay. Air Crapada has about the worst customer service going so be prepared to have to gate check the bag. Aeroplan has no sway so pay no attention to what they tell you. It's all up to the idiot at the gate. Want to avoid the possibility of any hassle? Ship your photo gear to destination via FedEx or similar. Hotels will accept packages for guests due to check in over the next day or so.
