What is one of the key requirements for RNP?

One of the key requirements for Required Navigation Performance (RNP) is continuous flight path monitoring. This requirement ensures that the aircraft is consistently adhering to its intended flight path, which is vital for maintaining accuracy and safety in navigation. RNP involves specific navigation criteria that rely on the aircraft's ability to navigate with a certain level of precision. Continuous flight path monitoring allows for the detection of deviations from the planned route, enabling timely corrective actions. This is essential for operations in airspace where high levels of precision are necessary, such as in en-route phases or approaches to closely spaced runways.

Other requirements within RNP procedures may include system performance, crew training, and adherence to designated operational capabilities, but continuous flight path monitoring stands out as a fundamental component for ensuring that the aircraft remains on the planned trajectory throughout its flight.