Precise GNSS Product-Aided Flight Inspection System

Y. Wang, X. Shi, P. Wang

Abstract:	As any other electronic devices, radio navigation aids (VOR, ILS, NDB, VASI, DME, etc.) could fail, lose strength or accuracy, be out of tolerance or provide wrong information, with a prospective disas-trous impact on aviation safety. Aviation authorities induce a process called Flight Inspection (FI) to periodically check, verify and certify radio navigation aids and procedures, complying with interna-tional standards. Besides, FI process also support accident investigation, restoration of facilities with unscheduled outages, reported malfunctions, site evaluation, commissioning inspection of new facili-ties or procedures, etc. Aircrafts equipped with dedicated hardware called Flight Inspection System (FIS) are usually employed to achieve FI process. The Flight Inspection System with dedicated anten-nas, computers, monitors, receivers/transceivers and sensors is an inflight evaluation tool used for in-vestigation and evaluation of air navigation aids and instrument flight procedures to ascertain or veri-fy compliance with established tolerances and safety of flight. To FIS, the real aircraft position is es-sential and obtained by GPS-based technologies (standalone GPS and RTK) mainly in current FIS products. However, the limited valid coverage of RTK and performance limitation of standalone GPS make current FIS fail to cover the whole RNAV procedure flight inspection and flight validation, espe-cially GNSS RNAV procedures. For an effort to replace the current FIS to an enhanced system with a larger operating envelope while maintaining or improving its efficiency and accuracy, in this paper, Precise GNSS Product-Aided Flight Inspection System (PPAFIS) is introduced, which overcomes shortcomings (mentioned above) of cur-rent flight inspection systems. In PPAFIS, predicted precise satellite ephemerides (about 5cm, 95%) and clock (about 3ns, RMS) from IGS Ultra-Rapid data are applied to achieve precise positioning dur-ing the whole procedures. In this system, a special module containing one dual frequency GPS receiver, a data storage and calculation unit, perform PPP-like positioning over the whole inspection flight. This special module can converge fast with aiding information from RTK in initial flight phase, and main-tain continuous precise position output by “Rotational Fast Converging” strategy during other phases far away from RTK operation envelope. The PPAFIS concept has been verified in both mathematical and physical simulations. IGS Ultra-Rapid satellite ephemerides and clock, real ground observation da-ta (RTK + a dual frequency GPS receiver), real flight inspection data taken from Collaborative Flight Inspection System (CFIS) in cooperation with the Flight Inspection Center of CAAC are all involved in the analysis work. The results confirm that the strategy and algorithm are feasible, and able to produce position output meeting GNSS RNAV procedure flight validation and inspection requirements suffi-ciently. And potentially, PPFIS has the prospective ability to not only enhance ILS flight inspection, along with other facilities in and around airfields, but perform new generation GNSS flight testing, such as COMPASS.
Published in:	Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013) September 16 - 20, 2013 Nashville Convention Center, Nashville, Tennessee Nashville, TN
Pages:	292 - 300
Cite this article:	Wang, Y., Shi, X., Wang, P., "Precise GNSS Product-Aided Flight Inspection System," Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013), Nashville, TN, September 2013, pp. 292-300.
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