scope:

PURPOSE.

This notice proposes interim guidance for approving the installation of global positioning system (GPS) equipment to be used as a primary means of navigation for oceanic/remote operations (including minimum navigation performance specifications (MNPS) airspace). To clarify terminology, this guidance adopts the term "primary means of navigation" as opposed to "sole means of navigation" to identify navigation equipment which provides the only required means on the aircraft of satisfying the necessary level of accuracy, integrity, continuity and availability for a particular area, route, procedure or operation. The failure of a primary means of navigation may require reversion to a non-normal means of navigation (e.g., dead reckoning). Examples of systems which can provide a primary means of navigation include: very high frequency omnidirectional range (VOR) for domestic en route, terminal, and nonprecision approach where it is available; VOR/distance measuring equipment (DME) for domestic en route above flight level 240, terminal, and nonprecision approach where it is available; Omega for oceanic operation; and inertial navigation systems (INS) for oceanic operation. The GPS installations which revert to another long-range navigator, such as Omega or INS, need not apply for GPS primary means approval; they may utilize GPS under supplemental Instrument Flight Rules (IFR) approval.