How to carry oversized Vietnamese conical hats (non la) as hand luggage on the plane?

You can stack the conical hats inside one another and carry them as hand luggage in a large bag or cover — many travelers do this without issues.

No special packaging is required — just stack the hats and put them in a bag or cover.

If the airline has strict rules on the number of carry-on items, staff may ask you to combine the hats with your main carry-on bag instead of treating them as a separate piece — worth checking in advance.