We’ll call the above usage of RNAV and RNP the colloquial definitions. The Pilot/Controller glossary defines RNP as a “statement of the navigational performance necessary for operation within a defined airspace.” For example, enroute navigation requires a rather loose RNP, while a precision approach requires a much tighter RNP. It’s the performance requirements that are expressed as required navigational performance (RNP) and the minimum RNP varies based on the type of usage. Remember that performance-based navigation (PBN) is a generic term that simply says you can have any box you want as long as it meets the performance requirements. Obviously, an old-school LORAN-C won’t have the accuracy of a WAAS-enabled GPS, or even an old rho-theta VOR/DME box. Simply put, RNAV is a generic name for any box that allows point-to-point navigation.Ī problem with this definition of RNAV is that it doesn’t address performance requirements. From the Pilot/Controller Glossary:ĪREA NAVIGATION (RNAV)-A method of navigation which permits aircraft operation on any desired flight path within the coverage of ground− or space−based navigation aids or within the limits of the capability of self-contained aids, or a combination of these. This is like saying, “I don’t care if you use Google maps, Apple maps or Mapquest, as long as you make it to the destination.” The problem arises with what to call this when performance is what matters and all we’ve used in the past is device-specific nomenclature.Įnter area navigation (RNAV). If you had an approved navigation device that met the performance requirements, regulators wouldn’t dictate what system to use. The idea behind PBN is simple: equipment used doesn’t matter performance does. The FAA has been articulating a performance-based navigation (PBN) strategy since 2003. These are generally referred to as global navigation satellite systems (GNSS). ![]() There are other satellite-based navigation systems such as GLONASS, Galileo and Beidou, and Garmin already makes devices that receive signals from multiple constellations. Peering into the future, GPS is too limited a moniker. The result is the term “GPS” that is now associated with multiple MOPS. GPS itself (TSO-Ĭ129) as a supplemental navigation system wasn’t good enough for approaches, so approvals as a normal navigation system (TSO-C145), incorporation of SBAS and selective availability awareness were added. It also means the localizer and glideslope receivers meet the minimum operational performance standards, or MOPS, of TSO-C36e and TSO-34e, respectively.Īll was fine until aviation got too smart for its own good. For example, an ILS approach means the localizer is transmitted on a VHF frequency and glideslope on a paired UHF frequency. Thus, a system used for an approach incorporated two aspects, how navigation information was received (the box) and the required performance of the system. ILS, VOR, NDB, GPS, etc.Įach individual system performed to a common standard. ![]() Approaches were designated based on the system used for lateral guidance in the final approach segment, e.g. We don’t make these up we just explain them.) When area navigation was first used for approaches, a standard and straight-forward naming convention already existed. The controversy surrounds defining RNAV/RNP and what those terms mean to pilots. ICAO wants to re-name RNAV approaches RNP and the FAA is balking at the idea-as are many other countries. The meanings that words convey are particularly important in aviation and are the genesis of a food-fight between ICAO and the FAA. But this is an over-simplification because changing the subject would make the quote non-sense: That which we call a fish by any other name would smell as sweet. Shakespeare elegantly downplays the importance of naming in Romeo and Juliet, writing: “What’s in a name? That which we call a rose by any other name would smell as sweet.” What matters is the subject and not what the subject is called.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |