GNSS Autonomous Integrity Monitoring with Barometric Pressure Measurements and Weather Data

Abstract

Vertical navigation is essential for new aviation operations like precision approaches and automatic landing which are expected to be primarily based on Global Navigation Satellite Systems (GNSS). However, achieving tighter vertical requirements with GNSS is challenging due to the inherent geometrical limitations. Current Aircraft-Based Augmentation Systems (ABAS) developments focus on proving that Advanced Receiver Autonomous Integrity Monitoring (ARAIM) is able to provide a robust operation for horizontal services and vertical guidance via the use of Multi-frequency and Multi-constellation GNSS. Although ARAIM can achieve high levels of integrity, the availability and continuity of the system may be compromised by the loss of satellites or high presence of cycle slips. For this reason, the support of onboard sensors like barometers is essential to guarantee all the vertical navigation requirements and extend the achievable accuracy and integrity for future even more stringent operations. This paper aims at augmenting GNSS navigation with geodetic altitude obtained from aircraft barometric pressure measurements and external weather data within a robust navigation architecture based on ARAIM. The present work describes the derivations of the threat and error models that are required for the inclusion of this barometric geodetic altitude into ARAIM. The improvement in availability is simulated world-wide with respect to the expected uncertainty of the geodetic barometric altitude. Then, real flight data is used to show the benefit of the barometer augmentation on the integrity of the navigation solution under real operational scenarios. The error models are obtained from several hours of flight data collected during a flight tests campaign performed in 2018 with the German Aerospace Center’s (DLR) Dassault Falcon aircraft.