Applicability

This regulation introduces the subpart that establishes who can serve as flight crew and what qualifications they must have for Part 121 operations (scheduled airlines and commercial operators). It applies to all certificate holders operating under Part 121, meaning every airline must follow these crewmember requirements regardless of their size or specific operation type.

In practice, this matters because it sets the stage for detailed regulations that follow, covering pilot qualifications, flight engineer requirements, flight attendant duties, training programs, and recent experience requirements. When you see regulations numbered 121.383 through 121.453, you'll know they all fall under this umbrella—they're defining who can work as crew on airline flights and what standards they must meet.

For pilots transitioning to airline operations, this subpart contains the core professional requirements you'll need to satisfy beyond your basic pilot certificates, including airline-specific training, checking, and currency standards.

*This is a plain-English summary for study only. The official 14 CFR text on this page is controlling — always read the current regulation and consult a CFI.*