So you're flying off on a wilderness backpacking vacation and you need to get your backpack to your destination. There are 4 ways to chosse from, which we'll discuss in order of the least safe to the most safe way to get it there.
1. Simply treat it like any piece of luggage. Cinch down all the straps, buckle up all the buckles, and say goodbye to it. I've actually done this countless times without my backpack being damaged but there is always a risk that some strap will get snagged in the conveyor belt.
2. Same as above but put it inside a clear bag of strong plastic. Some airlines will do this for you, sometimes without even asking.
3. Put your pack inside a duffel. If your duffel is too small to accomodate your packed pack, then take everything out and repack when you get there. If you have a duffel, or if you do this often enough to make it worthwhile to buy a duffel (which are pretty cheap at surplus stores), this is probably the easiest and safest.
However, methods 1 - 3 all run the risk that your baggage ends up someplace different than you do. To avoid that risk you can:
4. ship your bag via UPS to your destination. Of course there needs to be a location you can ship it to, and if you're getting right on the trail you might not have one. But if you do and you want to make absolutely sure you have the pack, this is the way to go and worth the expense.