Tightly coupled GPS/IRS navigation for ADS-B

The FAA has proposed challenging requirements for the ADS-B navigation sensor FAA´s recent Notice of Proposed Rulemaking (NPRM) for ADS-B concludes WAAS meets the proposed requirements but says the FAA is considering whether tightly coupled GNSS/IRS navigation is an acceptable alternative. Navigation systems that tightly integrate GPS with an Inertial Reference System (IRS) are indeed an excellent positioning source for ADS-B. Air transport and business aircraft are beginning to use such systems for a variety of reasons unrelated to ADS-B, for example to improve availability for RNP 0.1 operations. This trend will accelerate over the coming decade. This paper describes tightly coupled GPS/IRS navigation systems and the benefits they provide. It shows they not only meet the ADS-B NPRM requirements for horizontal positioning, but they also offer several additional benefits that enhance ADS-B´s capability to maintain air traffic flow under challenging conditions that would otherwise impede it.