You have the right to be present and observe when your bag is inspected and then to lock your bag with any sort of lock you want after the inspection is complete. Just ask when you check in.
Sometimes, a ticket counter clerk will say, "Sorry, but you can't lock your bag and you can't watch the inspection."
Your response is, "Oh yes I can." And if they persist, ask for a supervisor.
Clerks will sometimes deny this because it causes them extra work and they're lazy or because they're busy and it takes extra time. But, just insist.
I have done this in every major and many minor airports around the country. Coming back from Bladeshow this year with a valuable cargo, I told the ticket clerk that the bag was locked and I wanted to observe the inspection. Her response was, "Knife show, eh? Just take your bag down to that counter with the sign that says, 'oversized bags.'"
When I got to the oversized bags area, the TSA person said, "Sir, that's a standard bag. You can just check in for your flight nor..."
"It's locked."
"Oh, knife show I suppose. Ok, just put it up here." And that was that.
No airport has been built since 9/11 and so no airport is architecturally designed to accomodate the new bagage inspection requirments. As a result, every airport has figured out some way to shoehorn the new bagage inspection requirements into their available space. This means that the exact procedure for you to observe the inspection and then lock the bag vary from airport to airport.
It's a good idea to arrive plenty early if you intend to do this. In a few airports, you have to actually be escorted downstairs into the bagage handling area to do this (and now you know why the ticket counter clerk may initially deny that this is permitted). Here in Portland, at PDX, it's very simple: everyone at PDX has to carry his bag from the ticket counter to the inspection station (some airlines have skycaps who do this for first-class passengers, but I wouldn't know much about that). At the inspection station, you just tell the TSA technician that your bag is locked. They wil say, "Stand over there please," and you stand in a designated area until the technician says, "Your bag is clear Mr.... ah... mmmmm.... Ghoulnack?" "That's close enough, thank you." And off you go.
As for packing, while I don't doubt that some theft from bagage happens, I suspect that the majority of knives that "disappear" from checked bags simply slip out. Pocket knives are small and tend to have slippery surfaces. They can easily slip out unnoticed. So, pack your knife in a way that won't fall out. A favorite trick of mine is to put it into the back pocket of a pair of pants, the kind which has a button (or, better yet zipper or velcro) that holds the pocket shut.
When theft from bagage does happen, the thief generally has to act in a split second. He has just enough time to insert a hand, grab something, and pull it out. So, bury the knife deep inside of your bag. The idea of putting it inside of a pocket of a pair of pants serves this well.
The ultimate solution is to carry a gun. No, you don't shoot the baggage handlers. You just put the gun in your bag along with your knife. Be sure to follow the very specific requirements for guns in checked baggage. Then, when you check in, tell the clerk that your bag has a gun in it. Now, you are legally required to be there for the inspection and legally required to lock the bag after the inspection. And, your bag will receive special handling all the way. You'll even have to collect it at the airline's baggage office instead of off the carousel. The disadvantage of this method is that it will cause you considerable delay because such bags are handled separately -- usually last -- and there is extra paperwork to be done concerning them. But, for example, for a knifemaker or dealer traveling to a show with a considerable number of valuable knives, this extra security will be worth the extra delay. By the way, the gun doesn't have to be anything special; a cheap, little .22 is all you need.
