The Answer is Use a Good Flight Case
If you hope to get the instrument into the cabin, remember that some companies, RK for example, make flight cases that are designed for shipping instruments. Because the shipping case is shorter than a standard around-town case (there is no place for the bow) it is less likely to catch the eye of airline personnel. Keep in mind that some rack cases may still be slightly longer than the allowable size, and you'll need a case for your bow so you can carry it on board with you.
If you must ship your instrument, or stow it in the cargo hold, I recommend doing so only in a suspension case. The pads that support the top and bottom of the case's back go a long way toward protecting the instrument from shock. The shell that the case is built around should be strong, not flexible (plywood is better than Styrofoam). If the box is crushed, the case should be able to withstand the impact.
Rack case for violin
Take good case of your Musical Instrument during Transit,RK shares some important tips for traveling with your Musical Instrument.