SAE ARP5628

This document recommends design criteria for the flight deck Final Approach Spacing System (FASS). The FASS is a combination of hardware and software that is required to perform the Final Approach Spacing Function. The FASS is designed to enhance the operational efficiency of flight by providing the crew with a means to obtain a precise aircraft-to-aircraft arrival interval at the runway threshold during instrument approach operations. The FASS provides operationally acceptable speed guidance, appropriate crew alerting, and must be highly reliable and thoroughly responsive to the operational requirements and environment.