Which hat?

[Camas]

My mistake.  I could have sworn I remembered it being long-sleeve only.  You are both correct. 
Of course, totally aside from what's allowed, the propriety of wearing a short-sleeve shirt with what amounts to a suit coat is abjectly lacking.

I believe the Marine Corps requires a longsleeve shirt with service jacket (Service Alphas) but that's not the case with the Air Force.

[Eclipse]

It's very "Dilbert" and or NASA circa 1965.

If you've got a gut, it looks terrible.

[Luis R. Ramos]

Eclipse-

What is "Dilbert-like" or "NASA?"

Wearing a short sleeve-tie combination?

Flyer

[Eclipse]

Yes.





At least in most of these pics they are wearing the tie the proper length - the worst way to wear a
short sleeve shirt with tie is the "1-inch above" look", which accentuates your gut.



Long sleeves with the tie at, or below the beltline tends to make the person appear taller.
If you've got  nothing to "hide", well so be it, but most of the people I see on a regular basis wearing
a short-sleeved shirt with a tie have plenty to hide.

[abdsp51]

I have both a flight cap and service cap.  And I wear both depending on my mood and the nice thing it can do double duty for both CAP and my day job