Hat/Cap/Cover/Headgear?

[Mitchell 1969]

And not just not covered, but also if not in uniform. If you recognize a superior officer that happens to be wearing civilian clothes while you're in uniform and covered, then you render a salute and give the proper greeting of the day. An officer doesn't stop being an officer when they're in civilian attire.

Maybe in the USMC but this is not the case with the AF.

AFMAN 36-2203 3.6.7. Civilians may be saluted by persons in uniform. The President of the United States, as Commander in Chief of the Armed Forces, is always accorded the honor of a salute. Also, if the exchange of salutes is otherwise appropriate, it is customary for military members in civilian clothes to exchange salutes upon recognition.

Although not regulatory, both The Officers Guide and The Air Officers Guide circa 60's-70's mentioned that salutes could be rendered tocivilians, with particular mention of when being introduced to ladies. I have t seen recent versions of those books - do they still print them?