Air transportation security in the United States is regulated by the TSA , an agency of the US Department of Homeland Security . Passengers must provide a valid federal or state-issued ID in order to be allowed onto a flight . A person must also go through a pat-down procedure or a body scan before boarding a flight to ensure that they have no prohibited items . These security policies have been adopted by the US government ever since the 9/11 Terrorist Attacks in which terrorists managed to hijack several commercial airliners . Items that are prohibited on airplanes include firearms , tools , or other objects that can be used as weapons , explosive or flammable materials , and other dangerous or debilitating chemicals or substances
9/11 Terrorist Attacks
September 11 attacks
Air transportation in the United States