A strong case is essential, fill all voids with socks and underwear, loosen strings, add a strap to case so if it comes unlatched it still will not open, and don't count on "special handling", be there at the baggage shoot so you can catch your beloved instrument as it flys out.
That's my winning formula since 9/11 and I really would miss my old 5-string banjo.

Cheerily,
Charley Noble