I regularly fly with my 45L pack as carry on and have never had an issue (for either domestic or international flights).
I have flown with my mountain pack (a very generous 55L pack) before too, and again I haven't had any issues, though for this one I take out the aluminium back stays and waistbelt.
It doesn't matter what size the back is, the trick is to keep it light (or at least looking like it is light), and not make it full. If you have a full 45 you won't get on, but if you have an empty 60 you may have no problems at all. |