You will almost certainly have to check the guitar. I have a very valuable guitar that I brought form Dallas to Boston, I wrote to the guitar maker and was told that the guitar and case were made to stand the rigors of air travel. He said DO NOT LOOSEN THE STRINGS ... and the only additional precaution he suggested was that I pack the head with crumpled newspaper, above and below, to keep it from rattling.

I followed these instructions, and insured the guitar for its full replacement value. The guitar and I chnaged planes (twice RT) and we both survived without incident! I was most concerned about temperature changes, and watched it sit on top of the baggage vehicle on the tarmack at Cleveland for 15 minutes in 95 geree sun, before the 'ramp rat' tossed it onto the conveyor belt and into the belly of our craft. Except for a new nasty scratch on the case, everything was fine.

As a famous American once said, "Trust but verify" I would let the airline carry the instrument, but pay the extra cash to insure its full value! Good Luck!