Purpose: This document identifies and specifies the aircraft avionics functions necessary for operation in the emerging CNS/ATM environment. These capabilities are intended to satisfy long-term CNS/ATM operational objectives. The baseline for this document is post ACARS and FANS-1/A applications.

This document emphasizes broad use of data link communication, GNSS navigation and various surveillance capabilities to improve flight deck situational awareness. Advanced avionics equipment architectures, functional definition and functional allocation are included. The recommendations contained herein are intended to represent a high-level system view that can be broadly disseminated to airspace planners, data link service providers, airframe designers and other who participate in the avionics development process. This document represents broad airline and industry consensus.

ARINC Report 660A is an outgrowth of the original ARINC 660 document. It focuses on long-term CNS/ATM objectives including Free Flight. The architectures recommended by this document reflect current, evolving and end-state configurations. The architectures have been developed specifically to reduce software modification cost and software development time. By focusing on software development, airlines desire to expand onboard avionics functionality through planned software upgrades. The architectures are intended to enable incremental upgrades and incremental software approvals. In this respect, the software development and certification process must change. The airlines, airframe manufacturers and avionics suppliers must coordinate their efforts to convince the regulatory authorities of the need to simplify the certification and operational approval process without compromising safety.

The challenges to the industry set forth by this document require an unprecedented degree of cooperation within the industry. The benefits that the airlines expect are reduced avionics acquisition costs, reduced life cycle costs, early attainment of operational benefits, flexible software revisions, fleet commonality and additional avionics system growth capacity.