What Can I Not Take on a Commercial Airplane?
Commercial airlines each have their own lists of prohibited items, but the authority of the TSA, or the Transportation Security Administration, supersedes that of individual airlines in preventing certain items from being carried on an airplane in the U.S. Although many sharp or potentially hazardous personal items, like toiletries, are confiscated at the security checkpoints in airports, most of these items can be transported in a passenger's checked baggage and are merely prohibited as carry-on baggage. However, the TSA's prohibited items are not allowed in either cabin baggage or checked luggage.
Lithium Batteries
Although many types of batteries are allowed on commercial airliners, you may not pack a lithium-metal battery with over two grams of lithium. Smaller lithium-metal batteries and various sizes of lithium-ion batteries are allowed in your carry-on baggage but not in checked luggage.
Ammunition
You may be surprised that many airlines allow passengers to carry ammunition in their checked luggage. Check with your airline to verify the types and amounts of ammunition that may be carried in the luggage hold. However, the TSA restricts the transport of flares and gun powder in either checked or carry-on luggage for all commercial airline passengers.
Explosives
No explosives may be carried on board or stored in the checked luggage compartment of a commercial airplane. The TSA's list of prohibited explosives includes fireworks, dynamite, blasting caps, grenades, plastic explosives, flares and even any realistic replicas of explosives. The TSA specifies that not all prohibited items are listed by name, so if you have explosives not specifically named, they will be confiscated from your baggage as well.
Chemicals
Disabling chemicals like chlorine, bleach, tear gas, spray paint and large canisters of compressed gas are also prohibited. The TSA makes an exception for "small compressed gas cartridges," but you should inquire before bringing any gas cartridges aboard.
Flammable Liquids
Any type of fuel, whether liquid or gas, is prohibited on commercial airlines by the TSA. There are some exceptions for limited quantities of small, personal aerosol cans; check with airport officials for specifics. Lighters completely drained of fuel are allowed in your checked baggage, but never in your carry-on. Any other flammable materials, like paint, paint thinner and matches, are also prohibited.