With regulations constantly changing as threat levels rise and fall, you have to keep up with the rules on what you can and can't take onto an airplane. Don't get caught by surprise at the security checkpoint. Do your homework before you leave, and travel knowing you're in the clear.
Visit the TSA website for the latest list of prohibited items. As threat levels change, the Transportation Security Administration's security procedures change with them. TSA lists are a good guide for what you can't pass through security with in domestic airports. Don't ignore them, or you could end up throwing away prohibited items, at best, and raising security red flags at worst.
Check each airline's regulations by visiting its website. While most airlines have similar rules, carry-on requirements do vary, even if only slightly. Make sure your carry-on luggage fits the size and weight requirements for each airline on your itinerary, and don't get caught trying to carry on two bags if an airline only allows one. You can't talk your way out of a regulation on a crowded flight.
Know all international requirements. If you're traveling overseas, you may not be able to carry on the same items that you would be able to in the States. Check the regulations for each airport you plan to travel through, even if you may only be in the airport for a short layover. You should easily be able to find any information you need on each airport's website.
Call the airport or airline you're flying from or to and ask if you have doubts about any items. Security regulations can change at a moment's notice, so always double check just before you leave on your trip to make sure the threat level hasn't risen.
