Influence of Local Area Augmentation System Decorrelation Errors on the Inertial Coasting Performance

Andrey Soloviev and Frank van Graas

Abstract:	The paper addresses the use of Inertial Navigation System (INS) as a backup to the Local Area Augmentation System (LAAS) to improve the continuity for precision landing operations. Particularly, the paper evaluates the influence of LAAS decorrelation errors on the inertial coasting performance from the Category II (CAT II) decision height to rollout completion. The paper develops a mechanism of propagation of LAAS spatial decorrelation errors into errors of INS. The mechanism developed is based on a conservative approach that formulates the error propagation for the worst-case geometry scenario. The decorrelation error propagation mechanism is employed to evaluate the influence of tropospheric and ionospheric gradients of the INS coasting performance. Evaluations performed show that the tropospheric decorrelation contribution into the INS coasting error budget stays below the margin that is allocated to LAAS decorrelation errors after accounting for the contribution of inertial error sources (sensor errors and gravitational anomalies). Inertial drift caused by the ionospheric spatial decorrelation can however exceed the LAAS decorrelation error margin. A modification of the worst-case geometry error propagation approach into a geometry-dependent propagation of LAAS decorrelation errors and the use of relative carrier phase Receiver Autonomous Integrity Monitoring (RAIM) techniques are recommended to reduce the impact of iono gradients on the inertial coasting performance.
Published in:	Proceedings of the 63rd Annual Meeting of The Institute of Navigation (2007) April 23 - 25, 2007 Royal Sonesta Hotel Cambridge, MA
Pages:	372 - 382
Cite this article:	Soloviev, Andrey, van Graas, Frank, "Influence of Local Area Augmentation System Decorrelation Errors on the Inertial Coasting Performance," Proceedings of the 63rd Annual Meeting of The Institute of Navigation (2007), Cambridge, MA, April 2007, pp. 372-382.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In