Traveling on airplanes with musical instruments of any kind can be a challenge, particularly if we're considering professionals who are carrying fine violins as opposed to a child traveling with an inexpensive student violin. But violins are not double basses, just as piccolos are not sousaphones. Size matters.
As does the particular carrier you are flying with, as well as the interpretation of the rules by each plane's flight crews. The rules on United Airlines might be different from those on Spirit, American, Southwest, Alaska and JetBlue airlines. Even the time you board your flight can make a difference.
But at least there are, since 2015, U.S. Federal Aviation Administration rules that bring a semblance of order and universal rules - and prevent last-minute price gouging that plagued musicians for a long time.
The following provides a quick run-down of the rules and recommendations for violinists, violists, cellists, double bassists, and, of course, musicians who play the viola da gamba:
Small enough to carry on board (no seat) - Violins and violas are usually deemed small enough to carry on board on most flights. Tip: Pay for early boarding, as that makes it more likely you'll get space in the overhead bins near your seat.
Carry on board with a seat - While the rules are left to the discretion of each airline, it is possible to purchase a seat for a larger instrument (cellos and basses). Of course it makes sense to make that purchase in advance to ensure you and your instrument will be on the same flight. There is some judgment that may be left up to the flight crew as to whether your cello needs a seat in coach or first class, further emphasizing the need to work this out in advance.
Must check with baggage - When on-board space does not allow (which might happen with smaller regional carriers), it may be necessary to check your instrument. This is why your local violin shop recommends a sturdy case, even though many violinists would never consider checking their instrument; at such times, particularly in lieu of shorter regional distances, travel by car or train might make more sense.
Humidity issues - Planes as well as destinations might have a very low humidity factor. This is potentially an issue for the instrument if you originate in a humid environment. Humidifiers in the form of sponges in specially constructed containers are available to release moisture in a controlled fashion; ask your violin maker about whether he or she carries these in their violin shop.
TSA screening - Minimize any additional items inserted into your violin's case, as it might prompt the Transportation Safety Authority employee to open and handle the instrument in order to examine it. It is more likely to sail through x-ray screening hands-free if the instrument and bow alone are contained in the case.
Non-stop, direct, connecting and smaller (regional) planes - If you have to change planes on a trip it means repeating the boarding procedures and possibly educating a new flight crew on what you're doing. Or if you have a larger instrument that is checked in baggage, it's one more opportunity to be mishandled or lost. So choose your itinerary to be as direct/non-stop as possible.
So is travel worthwhile, given all these factors? Only you can decide. But the greatest musicians travel the most - follow their lead and learn to adapt.