What does 14 CFR Part 121 primarily regulate?

14 CFR Part 121 primarily regulates the operating requirements for domestic, flag, and supplemental operations of U.S. air carriers and commercial operators. This encompasses a wide range of safety and operational standards, particularly related to large aircraft operations. Within this regulatory framework, one significant focus is on crew qualifications and training, as safety in airline operations hinges on well-trained personnel.

The regulation mandates specific training protocols, operational procedures, and maintenance standards that aircraft operators must adhere to ensure safe air travel. By establishing requirements for crew training, 14 CFR Part 121 aims to ensure that flight crews are competent and prepared to handle various operational scenarios as well as emergencies. Hence, the emphasis on crew qualifications and training directly relates to maintaining safety and operational integrity in commercial aviation.