Which Part addresses Domestic, Flag, and Supplemental Operations?

• A. 14 CFR Part 121
• B. 14 CFR Part 135
• C. 14 CFR Part 93
• D. 14 CFR Part 73

Answer: (A)

The key idea here is identifying which regulation governs large U.S. air carrier operations that are scheduled and international in scope. The part that matches the description “Domestic, Flag, and Supplemental Operations” covers the rules for these scheduled air carriers, including how the certificate is issued, what aircraft and equipment are allowed, crew qualifications and rest requirements, flight operations procedures, maintenance programs, manuals, training, and overall safety oversight. It sets up the framework for operating and maintaining large, scheduled service—whether it stays domestic or extends to international routes under a U.S.-registered carrier.

That’s why this choice is the best: the phrase “Domestic, Flag, and Supplemental Operations” is exactly how this regulation is described in the CFR, and it targets the certification and operation of the major scheduled air carriers. The other options refer to different regulatory areas: on-demand air taxi and charter operations have their own rules, general aviation operations fall under general operating rules, and the remaining choice concerns special use airspace rather than carrier certification and operations.