Applicability

This regulation introduces Subpart N of Part 121, which covers flight operations requirements for air carriers. It establishes that the rules in this subpart apply broadly to all Part 121 certificate holders (scheduled airlines and certain commercial operators) unless a specific regulation within the subpart states otherwise.

In practical terms, this means when you're operating under Part 121, you must comply with all the flight operations rules that follow in Subpart N—covering areas like crew duties, flight planning, weather requirements, and operational procedures—regardless of which type of Part 121 operation you're conducting. The "except where otherwise specified" language simply acknowledges that some individual regulations within this subpart may carve out exceptions for specific types of operations (like domestic versus flag operations) or aircraft configurations. This applicability statement serves as the foundation for understanding which operational rules you must follow as a Part 121 pilot or operator.

*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.*