The Impact of Measurement Biases on Availability for Category III LAAS

Jason H. Rife and Sam P. Pullen

Peer Reviewed

Abstract: This paper examines the availability impact of biases on the Local Area Augmentation System (LAAS). An upper limit for tolerable LAAS biases is determined using an ideal error bound based on an improved LAAS messaging structure. Simulating Category III (CAT III) LAAS installations in the conterminous United States (CONUS) subject to an availability requirement of 0.999, the modified message structure permits biases as large as 40–78 cm for a typical airport (but only 8–18 cm for a worst-case airport). Sigma-inflation techniques provide a means to bound unknown biases without requiring any modification to the LAAS message. Standard closed-form techniques for sigma inflation are overly conservative and tolerate biases only half as large as the ideal case. Position-domain inflation techniques that provide better bias tolerance are described. These techniques achieve nearly identical performance to the ideal case without requiring modification of the LAAS message.
Published in: NAVIGATION, Journal of the Institute of Navigation, Volume 52, Number 4
Pages: 215 - 228
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