Human Systems Integration Division @ NASA Ames

A primary feature of the NextGen is trajectory based operations (TBO). Under TBO aircraft flight plans are known to computer systems on the ground that aid in scheduling and separation. FANS is presently the primary flight deck system in the US supporting TBO, but relatively few aircraft are FANS- equipped. Thus any near-term implementation must provide TBO procedures for non-FANS aircraft. Previous research has looked at controller clearances, but any implementation must also provide procedures for aircraft requests. The research presented here aims to surface issues surrounding TBO communication procedures for non-FANS aircraft and for aircraft requesting deviations around weather. Procedures were developed to stringently follow TBO principles, in particular minimizing the discrepancy between flight plans stored in a ground based system and the flight plans actually flown. Three types of communication were explored: Voice, FANS, and ACARS. ACARS is a digital communication system widely used in the US for communication between aircraft and their Airline Operation Centers (AOCs); it differs from FANS primarily in that FANS allows the uplinked flight plans to be automatically loaded into the FMS, while ACARS delivers the flight plans in a text format that must then be entered manually into the FMS via the CDU. These procedures were used in a medium fidelity simulation. Sixteen pilots (eight two-person flight decks) and four retired controllers participated in 20-minute scenarios that required the flight decks to navigate through convective weather as they approached their top of descents (TODs). In this context, the rate of non-conformance across all conditions was higher than anticipated, with aircraft off path in excess of 20% of the time. Controllers did not differentiate between the ACARS and FANS datacom, and were mixed in their preference for Voice vs. datacom (ACARS and FANS). Pilots uniformly preferred Voice to FANS, liking ACARS least.