I have a decent solution sorted out that has worked for me going across the world. (No, it's not basses in every country ! LOL)
Wooden guitar cases and even the sturdier road cases(that are still wooden underneath) are not the best solution. My favorite thus far is a molded case that is made by SKB. I have taken this case across the world(literally) and have had no issues with the guitars inside. From Germany to Ireland, Canada to California, this case has weathered many flights and arrived unscathed. TSA can open it and look inside and lock it back up with ease. (There is also a *certain* gig bag that holds two basses that will fit comfortably inside this case.)
Here is the link to SKB's website for the dimensions etc of the case,
and Happy Flying!!!!