Flying from Kathmandu to Vancouver (HELP! Please)

Tibet's entry requirement is different from the rest of Mainland China in a way that all tourists are required to have a Tibet Travel Permit plus a valid Chinese visa. Not so sure whether this also applies to a two-hour stopover (conflicted information on the internet) but don't be surprised if the airline refuses to take you when you are checking-in. Also keep in mind that even if you somehow made the flight, you may be questioned extensively by the border officer who has the authority to send you back for not having a visa or a TTP. You'd better change your flight to avoid the hassle.