Applicability

This regulation identifies who must follow the rules in this particular subpart of Part 121. It applies specifically to certificate holders conducting supplemental operations—these are air carriers that operate on-demand or charter flights rather than scheduled service.

The subpart establishes the framework for how these supplemental operators must obtain FAA approval for the geographic areas and specific routes they want to fly. This is a critical administrative requirement because supplemental operators can't simply fly anywhere they choose; they need prior authorization for their operational areas and flight paths.

In practical terms, if you work for or fly with a Part 121 supplemental carrier (like a charter airline), this subpart governs how your company gets permission to operate in different regions and along different routes. The approval process ensures the FAA can verify that operators have adequate planning, support, and safety measures for their intended operations.

*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.*