Description / Abstract: This document reports on the Global Positioning System (GPS) and related parameters, for operation and use of a GPS-based navigation system by civil users of the airspace. The report considers the use of GPS both as a supplemental and as a sole means system for en route, terminal area, and non-precision approach operations. Integrity monitoring requirements are presented with a discussion of suitable methods for determining GPS integrity and broadcasting this information to civil aeronautical users. Coordinated with EUROCAE.