14 CFR Part _____ requires all passengers to comply with crewmember instructions.

• A. Part 135
• B. Part 121
• C. Part 91
• D. Part 145

Answer: (B)

Following crewmember instructions is essential for flight safety, guiding passengers through boarding, safety briefings, seat belt use, and actions during turbulence or emergencies. This explicit requirement is part of 14 CFR Part 121, which governs scheduled air carrier operations. Part 121 sets the rules for how passengers must behave aboard carrier aircraft and the authority crewmembers have to enforce those instructions. The other parts cover different operations—Part 135 for on-demand air service with smaller aircraft, Part 91 for general aviation and noncertified operations, and Part 145 for maintenance facilities—so they don’t carry this specific passenger compliance mandate in the same way as Part 121.