Great info from Timfitz63. I will print a copy out and keep it handy.
Depending on the plane and when you board, the overhead bins may not be big enough to hold a guitar or there may not be room left in the overhead bins. Because of this you should prepare your guitar to go as checked baggage. My suggestion on packing the guitar is to:
1) Take pictures of the guitar and how it's packed in case you need to make a claim.
2) Tune the guitar down a half-step from where it is normally tuned, this reduced the tension but still provides some, the neck should be stable this way.
3) Fill all open areas in the case with loosely crumpled up packing paper. This is important, do not tightly crumple the paper or put pressure from the guitar to compress the paper. You can use news paper but risk ink getting on the guitar. When the guitar is packed you should be able to shake the case (hopefully you have a case and not a gigbag) without hearing the guitar move. All this applies for a gigbag too but the risk is obviously greater.
4) Put a few 'Fragile' stickers on the outside of the case.
5)Once all this is done you are at the mercy of the baggage handlers and conveyor belts. For the most part, neither of these will show a guitar and mercy. I try to carry the guitar as far as possible. Try to avoid checking it at the counter. You are better off Gate Checking it if possible, less handling by the airline. Also, when you Gate Check an item it is delivered to you on the Jetway ramp when you deplane, avoiding additional handling by the airline.
6) Good luck!
If you go through security with the guitar, if possible, watch it on the monitor when they scan it. I think it looks pretty cool.
