Final answer:
According to Part 91, Subpart F of the Federal Aviation Regulations, if an airplane is required to have signs indicating that smoking is prohibited and seat belts must be fastened, the crew must turn on those signs.
Step-by-step explanation:
According to Part 91, Subpart F of the Federal Aviation Regulations (FARs), if an airplane is required to have signs indicating that smoking is prohibited and seat belts must be fastened, the crew must turn on those signs.
These signs serve as visual cues for passengers to follow safety regulations. When the signs are turned on, passengers are expected to refrain from smoking and fasten their seat belts.
By complying with these regulations, the crew ensures the safety and well-being of everyone on board the aircraft.