Squeeze anything protruding from the backpack, stuffed in exterior pockets or clipped to the outside of the pack all the way into the pack or into a separate piece of luggage. This includes sleeping bags, water bottles, extra pairs of shoes and sleeping pads. If you don't take this precaution, items might become lost, damaged or incur oversize luggage fees.
Pack only items that are not on the TSA's list of prohibited items (see Resources section). If you're using your backpack as a carry-on, remove any liquids greater than 3.4 ounces from it and place these in your checked bags or throw them out; they won't be allowed through the carry-on security checkpoint. Items like aerosol bug repellent and stove fuel won't be permitted through security checkpoints in checked or carry-on bags, so properly dispose of these before entering the airport. You'll have to purchase new items when you arrive at your destination.
Pack all your liquids, gels and creams--including bug repellent--that you're planning on taking through the security checkpoint and that are less than 3.4 ounces in size into one clear, quart-sized, zip-close plastic bag. This requirement is the same for backpackers as it is for all other travelers. Pack the quart-sized baggie of liquids near the zipper of your backpack so it's easily accessed, and send it through the X-ray machine separately from your backpack.
Fasten all buckles and straps before placing the backpack on a conveyor belt, whether for the checked luggage line or carry-on luggage.
Place your backpack in a large plastic bag, a rain cover put on backwards or even a large duffel bag if you're planning on checking it. This will help prevent the straps and buckles from getting caught in the conveyor belt and badly damaged. Some airlines will provide large plastic bags for your backpack or a plastic bin in which it can ride the conveyor belt, but never count on these amenities, as they're not guaranteed.
