Several U.S. federal agencies regulate the activities of foreign airlines in the U.S. and of U.S. airlines worldwide.
DOT regulates the "business" of operating an airline. It has extensive regulations concerning advertising, passenger rights, the rights of passengers with disabilities, and more.
The FAA regulates all aspects of private and commercial aviation activity in the U.S. and provides air traffic control services. FAA regulations affect aircraft operators and repairers and manufacturers of aircraft, engines, and parts.
Agencies: DHS (TSA, CBP)
The Department of Homeland Security also regulates aviation extensively through the Transportation Security Administration and, for international flights, U.S. Customs and Border Protection.
Separate webpages on economic regulation and safety & security regulation provide details of the Firm's expertise.