What is the RNP value for enroute navigation used in the U.S.?

The RNP (Required Navigation Performance) value for enroute navigation used in the U.S. is RNP 4.0. This value represents the standard for lateral navigation accuracy that is required for enroute operations within the National Airspace System.

RNP 4.0 indicates that an aircraft must be able to stay within a path that is defined by 4 nautical miles (NM) of the intended route 95% of the time. This standard is part of the FAA's efforts to improve navigation precision and safety while maintaining efficiency in the airspace.

When comparing RNP 4.0 to other values, such as RNP 0.3, RNP 1.0, and RNP 3.0, it's important to note that lower RNP numbers imply higher navigational accuracy, which is not required for general enroute navigation in the U.S. Instead, RNP 4.0 is suitable for the enroute phase of flight, while lower values are generally reserved for terminal operations or specific precision approaches where tighter tolerances are necessary. Thus, RNP 4.0 effectively balances safety and operational efficiency for enroute navigation.