Southwest Airlines is a TSA PreCheck participant, meaning that at participating U.S. airports, qualified travelers can take advantage of accelerated security screening. To be eligible for PreCheck benefits, Southwest TSA  PreCheck you must input your Known Traveler Number (KTN) while making your travel reservation. Shorter lineups are usually available in the TSA PreCheck lane, and travelers are spared from taking off their laptops or liquids from their baggage, as well as having to take off their shoes, belts, and light coats. Both domestic and some foreign flights can use this service. To ensure a smooth booking and check-in experience, make sure your KTN is preserved in your Southwest Rapid Rewards profile.