The short answer is no; the long answer is what kind of hat are you wearing?
In short, a personal item and carry-on consists of hand baggage. Thus, a hat under, in my opinion, counts as head baggage.
On a recent trip, I attempted to bring back a gorgeous, hand-painted and handcrafted Vietnamese straw hat that I knew wasn't going to fit into my personal item or carry-on luggage.
This is certainly not like bringing a typical backpack or briefcase!
(Besides, why would I want to check in? No one wants to check in.)
Though all airlines have guidelines and regulations-and headware generally doesn't count-it's worth keeping in mind that airport security and the checkpoint are usually the places you don't have to worry about.
In my experience, it is the gate where policies are usually enforced.
Boarding my flight from Danang International Airport (DAD) and Taiwan Taoyuan International Airport (TPE), I wasn't questioned at all. It wasn't until I made it to Los Angeles International Airport (LAX) that I encountered a lot more resistance, probably, because, in addition to the hat, I was also wearing a fanny pack.
After some discussion, the gate agents would let me through if I put the fanny pack in my carry-on bag, which I was able to.
He is wearing a hat to escape detection.
The key part of this is that most passengers will probably have to wear it boarding the plane (plus, nobody wants to carry their hat around).
I also saw plenty of people wearing hats throughout the journey, but more of the baseball-hat variety.
Obviously, just because my hat didn't fit in the overhead bin doesn't mean yours won't. I had significant size restrictions, but in short, this may be something to keep on your body.
In my humble opinion, all hats should be created (and treated) equally. DEI this.
