What do Instrument Flight Rules (IFR) require of pilots?

The requirement for pilots operating under Instrument Flight Rules (IFR) is to use instruments for navigation and control. IFR is a set of regulations under which a pilot operates an aircraft in weather conditions generally poor enough to require reliance on instruments for navigation. This means that pilots must be proficient in interpreting instruments like altimeters, artificial horizons, and navigation displays, and they must make decisions based on the data these instruments provide rather than visual references outside the aircraft.

This framework promotes safety and allows pilots to operate in a wider range of weather conditions, as they can rely on their instruments to guide them safely to their destination when visibility is compromised. It contrasts with visual flight rules (VFR), where pilots are allowed to navigate by sight.

The other options represent scenarios or requirements that do not align with the principles of IFR. Flying by sight alone relates to VFR operations, flying only during daylight hours does not accurately reflect the capabilities and regulations under IFR, and the obligation to land immediately during emergencies is not a specific requirement of IFR. Instead, IFR provides structured protocols for managing emergencies while remaining in instrument flight conditions.