I know most people have no issues and I have seen plenty of backpacks onboard, but I never want to have to deal with gate checking (as noted) with expensive optics and other things that are not well protected. I read (I think) someone say they even brought trekking poles onboard. That seems...
Definitely an issue for speed with several carriers if you wanted really quick access during a bear encounter. But that is probably even true with a shoulder sling if not routinely practiced. A rifle may not be a first choice for this type of fast action, close encounter (assuming it happens...
What, use real science. This is such a slippery slope and just the beginning. Well not really, we as hunters just need to be more aware and active. It is not someone else's problem, it is all of our problem.