A Critical Look at the IMO Requirements for GNSS

J.O. Klepsvik, P.B. Ober, and M. Baldauf

Abstract:	The IMO Resolutions A. 915(22) and A. 953(23) form the backbone of IMO’s requirements for Maritime Radionavigation Systems. A.953(23) gives the formal requirements and procedures for accepting new systems as ‘components of the World-Wide Radionavigation System (WWRNS)’, while A.915(22) must be viewed as a ‘positioning’ document related to requirements for future developments of GNSS to be considered within the framework of A.953(23). However, none of the existing and planned GNSS seem to be able to comply with the IMO requirements, particularly the requirements for integrity and continuity, as reported in several recent studies. The paper examines the IMO requirements in view of the Galileo design requirements, notably the aviation (Level A) integrity and continuity requirements for the Safety of Life service. The Level A risk allocations have been translated to the maritime scene of operation using risk exposure times appropriate for critical maritime navigation elements. In order to arrive at a consistent set of requirements, two different approaches have been analysed: a top-down approach based on a Target Level of Safety (TLS) requirement and a bottom-up approach based on a translated set of Galileo allocations. Both approaches seem to indicate that a total risk exposure time of 15 min or less will be required as a normalising risk period in order to allow present and future GNSS to comply with IMO requirements.
Published in:	Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007) September 25 - 28, 2007 Fort Worth Convention Center Fort Worth, TX
Pages:	1931 - 1942
Cite this article:	Klepsvik, J.O., Ober, P.B., Baldauf, M., "A Critical Look at the IMO Requirements for GNSS," Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007), Fort Worth, TX, September 2007, pp. 1931-1942.
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