I fly all the time, and am planning to take a guitar along this summer when I cross the country for a wedding. I asked the TSA guys in Jacksonville last week what the rules were regarding guitars in cases as carry-on. Their response was "We see them all the time, no problem." So security has no issues. The next step is to give the airline a call, and check on their carry-on policy. Every airline is different, and each type of aircraft has different capacities.

DON'T assume you can just put it in the closet up front. They are not nearly so accomadating as they used to be, as this has been abused. In the summertime, you MIGHT get it in, if you are very polite and smile nicely,(Depending on the airline, that is.) In Winter, forget about it. That closet is not for luggage, but for the coats of people in first class, and it gets filled up fast! The flight attendants will offer to gate check your instrument,if it doesn't fit in the overhead, which is much better than using baggage checks. It will be hand carried to the baggage department, and will be delivered to the entrance of the plane on your arrival. On smaller puddle jumper type aircraft, this is an almost certainty. So buy some insurance... give the guy taking your case $5 and ask him to pack it gently. You'd be suprised what a good investment that is.

Good luck,
Blues