Derivation of CNS/ATM System Requirements for the JPALS Shipboard Relative GPS System

Dennis King, Joseph Hansen, Dean Rudy and Frank Allen

Abstract:	The Navy’s Joint Precision Approach and Landing System (JPALS) Shipboard Relative GPS system (SRGPS) provides complete Navy-Specific CNS/ATM capability for shipboard operations. This includes Air- Ship, Ship-Air, Air-Air Communications; Navigation, Guidance and Control, Surveillance, and Air Traffic Management for all phases of flight including flight deck operations. Naval-specific CNS/ATM requirements prevent direct application of civil requirements, making system-level allocation a challenge. The paper describes a Target Level of Safety approach to the problem, resulting in performance allocations to all SRGPS functions and to all phases of flight, providing civil levels of safety, but supporting military-specific operations that do not have a corresponding precedent in existing civil standards. The methodology described in the paper would apply to the derivation of requirements for any safetycritical GPS-based CNS/ATM system or sub-function. The paper describes the overall allocation process, starting with the definition of operational requirements for the SRGPS system. These were then developed into a set of functional requirements for Navigation, Data Linking, Guidance and Control, Surveillance, Collision Avoidance, and Air Traffic Management. Basic performance requirements for all of these functions were derived, and then a detailed risk analysis and allocation process was performed, allocating risk to all phases of flight and all functions. The result was a set of performance allocations which meet an overall Target Level of Safety in line with civil safety standards, yet which allow operations which are undefined in the Civil Aviation community.
Published in:	Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002) September 24 - 27, 2002 Oregon Convention Center Portland, OR
Pages:	1985 - 1995
Cite this article:	King, Dennis, Hansen, Joseph, Rudy, Dean, Allen, Frank, "Derivation of CNS/ATM System Requirements for the JPALS Shipboard Relative GPS System," Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002), Portland, OR, September 2002, pp. 1985-1995.
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