I carry a small one every day to work. First one I got was a lemon - closed up with a finger tap on the spine. This one locks solid - plus the LAWKS for extra measure. I have large hands, and it is small and not real smooth to open - but the bead blasted plain edge is very innocuous for office use. I relpaced a serrated Delica that I used to take to work (sheepy IT area). I haven't used it on a plane yet, but I imagine it would be fine.
BTW, I have taken a Delica and multi-tool on planes in my carry-on. I always take a daypack for "stuff" - cameras, paperback book, diagonal cutter for cutting tiewraps off my checked luggage, hat, etc. I put my 'tools' in there, never a look.