***Link*** :: [Part 121 Operating Requirements: Domestic, Flag, and Supplemental Operations](https://www.ecfr.gov/current/title-14/chapter-I/subchapter-G/part-121?toc=1) ***Description*** :: `= this.link` ***Author*** :: [[FAA]] These are the FAA's rules for operating an airline. These are the rules United Airlines lives by. Airlines must have an "Air Carrier Certificate" to operate under Part 121. Pilots flying for a Part 121 airline must have an Air Transport Pilot certificate. #source #far