An RNP level or type is applicable to a selected airspace, route, or procedure. The applicable RNP is expressed as a value that represents a distance in nautical miles from the intended position to the actual position of an aircraft. It is within this distance that an aircraft would normally be expected to operate. For general RNAV approach procedures, RNP-0.3 is required.
Aircraft meeting RNP criteria will have an appropriate entry, including special conditions and limitations, if any, in the Aircraft Flight Manual (AFM) or itssupplement. This will only occur when it has been determined that the aircraft complies with the appropriate provisions of certification.
Some aircraft have RNP approval in their AFM without a GPS sensor. The
lowest level of sensors that the FAA will support for RNP service is DME/DME. However, necessary DME NAVAID ground infrastructure may or may not be available at the airport of intended operations. For those locations having an RNAV chart published with LNAV/VNAV minimums, a procedure note may be provided such as “DME/DME RNP-0.3 NA”; this means that RNP aircraft dependent on DME/DME to achieve RNP-0.3 are not authorized to conduct this approach. Where FAA flight inspection successfully determines the availability and geometry of DME facilities will support RNP-0.3 and that the DME signal meets inspection tolerances, a note such as "DME/DME RNP-0.3 Authorized” will appear on the chart. And where DME facility availability is a factor, the note may read “DME/DME RNP-0.3 Authorized; ABC and XYZ Required”; meaning that ABC and XYZ facilities have been determined by flight inspection to be required in the navigation solution to assure RNP-0.3.