Correction of Inertial Navigation with Loran C on NOAA's P-3 Aircraft

Abstract

The National Oceanic and Atmospheric Administration (NOAA) maintains two Orion WP-3D aircraft based in Miami, Florida, and used for atmospheric and oceanographic research in support of NOAA projects and missions. Good navigation is essential to such research and we show that Loran C combined with inertial navigation results in substantial improvements. In particular, a method based upon symmetric filters can, in postprocessing, correct for inertial navigation errors in position, velocity, and horizontal winds. To test this method, data are compared with a high-precision, ground-based laser system operated by the National Aeronautics and Space Administration. Results show that errors in position and ground speed can be reduced to 0.2 km and 0.1–0.3 m s−1, respectively, in regions of good Loran C coverage. In addition, errors in heading are analyzed, and a method for partially correcting errors, based solely upon Loran C data, is presented. Results show that wind calculations are adversely affected and errors may be fully corrected only with another, more accurate source of heading, or with a Kalman filtering approach.