Which regulation outlines the requirements for IFR operations?

The regulation that outlines the requirements for Instrument Flight Rules (IFR) operations is FAR Part 91. This part is essential as it provides the foundational rules for all types of flight operations in the United States, including general aviation, and specifically addresses the requirements for conducting flights under IFR.

FAR Part 91 includes regulations regarding pilot qualifications, aircraft equipment requirements, and operational procedures necessary for flying in instrument conditions. This means that pilots must adhere to specific regulations set forth in this part to operate their aircraft safely and legally when visibility is limited or during adverse weather conditions.

Other parts such as FAR Part 121, FAR Part 135, and FAR Part 141 pertain to different categories of operations. Part 121 governs commercial airline operations and large aircraft, Part 135 covers commuter and on-demand operations, and Part 141 relates to pilot schools and the certification of those schools. Therefore, while these parts are important within their respective scopes, they do not specifically address the comprehensive set of rules applicable to IFR operations as outlined in FAR Part 91.