Yes. You can fly with your guitar as carry-on. And it's the law. In 2012, President Obama signed into law the ‘‘FAA Modernization and Reform Act of 2012,’’ which, along with provisions for enhancing runway safety and easing restrictions on transporting lithium batteries, contains the following text:
SEC. 403. MUSICAL INSTRUMENTS.
(a) IN GENERAL—Subchapter I of chapter 417 is amended by adding at the end the following:‘‘§ 41724. Musical instruments
‘‘(a) IN GENERAL—
‘‘(1) SMALL INSTRUMENTS AS CARRY-ON BAGGAGE.—An air carrier providing air transportation shall permit a passenger to carry a violin, guitar, or other musical instrument in the aircraft cabin, without charging the passenger a fee in addition to any standard fee that carrier may require for comparable carry-on baggage, if—‘‘(A) the instrument can be stowed safely in a suitable baggage compartment in the aircraft cabin or under a passenger seat, in accordance with the requirements for carriage of carry-on baggage or cargo established by the Administrator; and
‘‘(B) there is space for such stowage at the time the passenger boards the aircraft.