I am under the impression that hand carrying a guitar onto the plane is not allowed anymore due to terrorism issues.
I am also under the impression that unless the flight is not full, you are most probably going to have difficulty stowing the guitar onboard the cabin.
so what I do with my guitars is, I check them in as fragile. all my guitars have hard cases, so that makes it easier.
what you should do is, wind back the string a bit so that the tuning goes flat. you don't have to remove the strings, but just make sure you ease it off on the tuning. this ensures that the neck isn't under as much tension/stress when it is being stowed. also, I'm sure you will travel with socks and underwear, yah? stuff them around the guitar. wrap the bottom/base of the guitar with an underwear/soft cloth, so as to make the fit around the case more snug, and also to give it some extra cushioning. and oh, throw some silica gel into it as well. wrap it in a tissue paper or some paper envelope, and just chuck them into the guitar case. you do not want to know how much moisture can actually form on the instrument whilst being stowed in the luggage compartment!
last but not least, ensure your guitar case is securely fastened/clasped down. also make sure that it gets placed into the fragile/unusually shaped items cage. it should normally be to the side of the check in counters of most major airports.
and when you get to the country of destination, do not take it out of the case immediately. allow it to sit in the case overnight, so as to allow the instrument to acclimatise to the climate. you can open the case to see if there's any moisture that has formed as a result of the journey, and if so, quickly wipe it off with a soft cloth. but don't do anything with the guitar for a few hours until the instrument settles down.
these are the tips that have been handed down to me by many many luthiers/guitar techs in Australia.
have a safe flight!