Establishing Safety Case Strategies for Mission Planning or Situational Awareness Systems

Martin, B.J. and Reinhardt, S.L.D.W.

Mission Planning and establishing Situational Awareness are important risk management strategies in complex and hazardous military aircraft operations. Software based Mission Planning Systems (MPS) and Situational Awareness (SA) tools supporting operational decision making in circumstances that impact safety are now common place, and are becoming increasingly functional. Operational approvals for such systems are typically based on satisfactory technical specification compliance and user trials with criteria of: effectiveness, workload reduction over manual methods, sufficiently intuitive interface, verified outputs for selected operational test cases; and qualified user workforce. However, a conundrum remains for the structure of the system safety case argument, which would, in safety-related software theory, rely heavily on technical design assurances. The origin of many of the software tools forming part of a MPS is sometimes outside the environment where high integrity design assurance practices are common place. Often referred to in system safety literature as Software of Unknown Pedigree (SOUP). In this situation, the determination of a safety criticality / integrity level or hazard analysis activities do not typically drive system design requirements or design assurance activities. Therefore there are often substantial limitations in design development artefacts or other evidence that the software's integrity is likely to support the determination of safety criticality. Instead, from consideration of instituted MPS and SA tool approvals processes, it may be construed that system Human Machine Interface (HMI) look-and-feel evaluation and user operational procedures are largely responsible for achieving adequate operational safety. Yet, rarely are effective human error or critical task analysis activities employed for these tools and functions, nor are workload assessments used to validate in-mission operators abilities to detect and correct errors before mishaps occur. Examination of the limited literature or case studies identified of notable mission planning or situational awareness system related accidents, appears to weigh strongly towards user input or data related failures, and errors in correct system use due to incorrect initialisation or inadvertent reversion to default data values. These factors may be attributable to both technical and operational procedure design issues, although in some circumstances the causal factors have heavily favoured one over the other. Where then, should the strength of argument and emphasis of safety case resources be invested for maximum safety return? What is an effective safety case assessment methodology for MPS or SA systems approvals? This paper examines the current use of Mission Planning Systems, related accident history and causal factors, current regulatory requirements, and proposes a basis and methodology for architecting the safety case for MPS and SA systems.

Cite as: Martin, B.J. and Reinhardt, S.L.D.W. (2011). Establishing Safety Case Strategies for Mission Planning or Situational Awareness Systems. In Proc. Australian System Safety Conference 2011 (ASSC 2011) Melbourne, Australia. CRPIT, 133. Cant, T. Eds., ACS. 49-66

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