Description / Abstract: This document spans a decade of work by two RTCA Special Committees (151/171). During this period, alternative technologies to the Microwave Landing System (e.g., satellite navigation) have evolved. Yet the need for precision, near-airport area navigation continues. Whatever the navigation source for an operational capability, much of the material in this document is germane to any precision, terminal-area navigation system. The philosophy used in preparing the document was to provide guidance for any terminal area navigation system, although the specific performance requirements and test procedures assume the MLS Random (Area) Navigation (RNAV) sensor inputs.