The main problem is not strength of the case but locking.
Read this to see what can happen to instruments on airlines:
http://www.justinhayward.com/happeni...hives_027.html
In the US there is a standard security lock that airport security personnel have access to. You can get equipment cases that have that lock so you can lock it and they can unlock it with their key.
It makes it a bit more secure.
In the UK this is not possible so you can't lock anything.