As of March 6, 2015, it’s official and no longer at the discretion of the various airlines. According to the U.S. Department of Transportation, musicians who board planes must be allowed to carry on their instruments provided they fit in the overhead bin. If this space isn’t large enough, the musician is also permitted to purchase a second seat in which to stow their musical companion. One caveat: the airlines don’t have to prioritize musical instruments ahead of any other carry-on luggage, so if the bins are full, you’ll still have to check your instrument at the gate. To remedy this, the DoT suggests that musicians may want to pay the airline’s fee for priority boarding to ensure that there will be room for their gear.