I have carried many knives along when traveling, firearms etc. So long as you follow the rules, which vary a bit between carriers so I always check their web site or call to get verification in print before I head to the airport. The couple times I have been questioned I then showed the printed instructions to the gate person and there was no issue. In those cases the agent was not aware of the airlines policy but when reading it and verifying with a supervisor I moved through the process.