Code Share Agreement and Fly America
Code sharing is a commercial agreement between two airlines that allows an airline to put its two-letter identification code on the flights of another airline. In these arrangements, a U.S. air carrier may sell a seat on a flight that is actually operated by a foreign air carrier under a different flight number or code.
Compliance with the Fly America Act is only satisfied when the U.S. flag air carrier's designator code is present in the area next to the flight numbers on the airline ticket, boarding pass, or documentation for an electronic ticket identifies the U.S. flag air carrier's designator code or flight number.