Legally it will probably suffice, but I value my guns a little more than that, but not as much as others...
I prefer a box that has double locks and good hinges on it.. A metal box would be best...
Sig supply's a pretty good box but is all plastic.. (See attached)
When I carry something longer, I have a Bow case I carry (also plastic) that has two locks, and a metal pin through the hinge, but I also run a Cable lock around the whole case and through the handles. Is all this required??? No, of course not, but it provides some additional insurance (at least in my opinion / head).
So, how much security do YOU want around your gun while it is out of your sight and traveling with thousands of other bags through possible multiple cities?? It's your choice. It might be worth spending a few dollars for something a little more substantial..