Flying on a commercial flight has changed tremendously over the past few years. If you're thinking of flying someplace to go on a hike there are a number of things to remember, and things can change at any time. TSA has a listing of prohibited items, but what they say, and what they actually mean aren't always clearly spelled out. Listed below are some things I've found that you'll want to remember. REMEMBER, TSA will x-ray your bags and open them if they see something. If you're worried about something put it on top to hopefully prevent them digging open your whole pack.
LITHIUM BATTERIES - Spare lithium batteries are not allowed in checked baggage. When they are in the device they power they are not considered spare batteries. You may carry spare lithium batteries in your carry on bags. Check the link below for any changes.
OTHER BATTERIES - Other types of batteries can be carried with you, but not in checked bags so they can be monitored to prevent fires. Leave them in the original package if possible, otherwise insulate the ends and pack so the ends won't contact each other, or from coming in contact with metal. I once put a small watch battery in my pocket with spare change. I found the change got pretty hot after awhile. TSA has a hole page on batteries other than lithium. Check them out at the following link. Expect that it could change at any time.
STOVES - TSA states that you can carry a camping stove, but only if it's empty of all fuel, and cleaned so there are no vapors or residue left. No matter how good you clean your stove, someone at TSA may think otherwise. According to the Alaska Fish & Game, a number of people have showed up at local stores looking to buy a new stove after theirs was confiscated by TSA. You'd be better off buying a new stove and fuel bottle for your trip. For the return trip you take a chance of your stove making it home or, mail it home. There are reports of people using stove that utilize removable fuel canisters can make it through.
FUEL - Don't even think of taking fuel. This includes canisters of fuel. You can always buy fuel when you reach your destination. Its not allowed on Amtrak either but I haven't been able to find anything on the Alaska Railroad's website prohibiting fuel.
LIGHTERS - Not allowed! Buy some when you land.
MATCHES - One book of safety matches is permitted for carry on only. None in checked bags.
AEROSOLS - This includes bug sprays. You can't carry or these items as they are considered hazardous. You can take 4 ounces of personal care items, but why would anyone want to take hair spray backpacking? Don't laugh. I've seen items like this in bear boxes at Merced Lake High Sierra camp. Someone carried them in and didn't want to carry the weight out.
NOTE: you can take bug juice, just not the aerosol types. If you have 3 ounce or smaller you can carry it on, otherwise check it in.
FLARES AND FLARE GUNS - I can't see taking these items backpacking, but I guess someone might. Flares are not allowed in check or carry on baggage. Flare guns may be checked, but must be unloaded, packed in a hard-sided case, and declared at check-in.
KNIVES & TOOLS - You can't carry these items in you carry on luggage. This includes scissors. Put them in your checked bags and wrap them so TSA doesn't hurt themselves.
ANIMAL REPELLENTS - You can take chemical repellents, but less than 4 ounces, and the active ingredient is less than 2%. Good luck finding a bear repellent this small so buy some when you arrive at your destination.
FISHING GEAR - Fishing rods are permitted as carry-on and check baggage, but check with your carrier to confirm that it fits their limitations. Check your tackle equipment and reels.
UMBRELLAS - I've been looking at using an umbrella for hiking. It keeps the rain off, and you'll sweat a lot less. You can carry them once they've been inspected.
ICE AX - Checked bags only
SKI/HIKING POLES - Checked bags only.
HATCHETS/HAMMERS - Not on my list! But who knows? Checked bags only.
For a full list of prohibited items check out TSA's website. Remember that it could change at any time. Also check in with the airline you're flying with to see if they have any further restrictions.