What does IFR stand for in aviation terms?

In aviation, IFR stands for Instrument Flight Rules. This set of regulations governs the procedures for flying aircraft in weather conditions generally less than the minimums required for visual flight rules (VFR). Under IFR, pilots rely on instruments to navigate and maintain control of the aircraft rather than visual references outside the cockpit.

The IFR framework is crucial for maintaining safety and efficiency in controlled airspace, especially when visibility is limited. It entails specific flight procedures, communication with air traffic control, and adherence to airspace structure. Pilots operating under IFR are required to have specific training and ratings, which equip them to handle the complexities of navigating solely using instruments, such as altimeters, headings, and navigational aids.

The other options provided do not pertain to established aviation terminology, making them incorrect within the context of aviation rules and practices.