Under which FAR section does it state that pilots must not operate under the influence of drugs or alcohol?

FAR 91.17 explicitly prohibits pilots from operating an aircraft while under the influence of drugs or alcohol. This regulation outlines specific limits for alcohol consumption and mandates that pilots must not fly within a certain time frame after consuming alcohol, ensuring the safety of both the pilots and the passengers. The regulation aims to maintain high standards of safety in aviation by preventing impairment that could impact a pilot's ability to operate the aircraft safely.

The other options refer to different regulations within the FARs. For example, FAR 91.19 deals with carrying drugs and alcohol on commercial flights, while FAR 61.47 outlines requirements for pilots who are receiving training from an instructor. FAR 91.15 addresses the prohibition on the use of drugs and alcohol by passengers, rather than pilots. Each of these regulations plays a different role in ensuring safety and compliance within aviation operations, but FAR 91.17 is specifically focused on the conduct of pilots regarding drugs and alcohol.