After several brazen airplane hijackings in the early 1960s, the federal government established a small program to protect air travel with specially trained law enforcement officers. Since 9/11, the number of air marshals has grown dramatically, and today these federal agents are charged with keeping flight crews and passengers safe aboard civil aircraft. The transportation security administration also deploys air marshals to patrol railways and other public transport systems as part of its Visible Intermodal Prevention and Response (VIPR) teams, as well as conduct investigative work on the ground.

To become a federal air marshal, applicants must first pass a rigorous screening process that includes written applications, a medical exam, physical training, a psychological assessment, a polygraph, and other tests. Candidates also must have a bachelor's degree and be between the ages of 21 and 36. Those with advanced degrees can stand out in the hiring process and may command higher salaries than those without a college degree.

During their training, new air marshals are expected to work undercover and blend in with airline passengers. Once they have completed their training, they are tasked with investigating terrorist activities, human trafficking, and narcotics smuggling. They also assist FBI Joint Terrorism Task Forces and other local law enforcement agencies.

Due to the nature of their work, federal air marshals are on call 24/7 and must be ready to fly with little notice. They must also be prepared to relocate to other geographic areas as the need arises.