You can ban the guns on planes and fine people if anyone spots them. That should discourage open carry zealots. You could also ban carry-on bags, so it's harder

You can ban the guns on planes and fine people if anyone spots them. That should discourage open carry zealots. You could also ban carry-on bags, so it's harder to hide them. I guess people could bring on knives, pistols, or box-cutters; I don't know if there's a technical way to make planes resistant enough to these to give the pilot a chance to land in an emergency. There's still room for disagreement even after all of these, though.