The Benefit of Alternative Position, Navigation, and Timing (APNT) to Aviation and Other User Communities for Precise Time and Frequency Services

Positioning, Navigation, and Timing (PNT) services are the key basis for the provision of both essential (safety and security) and economically beneficial applications worldwide in the 21 century. Whether users are groundbased or sea-based or in the air, their primary/go to source of P and N and T is a Global Navigation Satellites System (GNSS). While the transition of various users/modes of transport from legacy PNT aids to GNSS is at varying stages, it is of concern that the ability of users to revert from the highly accurate positioning, area navigation (RNAV), and precise time provided by GNSS back to previous methods, which may provide lower levels of performance, will require higher levels of user skills, knowledge, and abilities – capabilities that may no longer be available when needed without significant investment in equipment sustainment and upgrade and in-depth training and practice.