One cleaning error and the cabin depressurizes. Rembember that you have a CONSTITUTIONAL right to have a gun so king George doesn't invade. That means that the dumbest f*** in the world can own one. Now let's put us in a hypothetical situation where a bunch of terrorists tries to hijack the plane and this time there are no really dumb f***s on board. So a few guys with guns start shooting the terrorists. It only takes one bullet through the window and it's bye-bye aircraft. I'd rather take my chances and stab a hijacker or two with a pen.