If you want to get technical, there are a couple of exception to this “rule”. Two of those exceptions are airports and hotel lobbies, since they are public places. Those are the only two places I wear the hat, since I am forced to at my current employer. When I was at XJT, I bought two hats. The FO hat, which was brought to IOE and promptly left at home for the next 12 years.....and the CA hat, which I promptly returned after one hour of wearing it to work.