Assuring Safety through Operational Approval: Challenges in Assessing and Approving the Safety of Systems-Level Changes in Air Transportation
Name
Weibel - PhD ICAT Report.pdf
Size
17.01 MB
Format
Adobe PDF
Checksum (MD5)
549ef9c00b62a1dbd81478c3309fdd89
Author(s)
Hansman, R. John
Weibel, Roland E.
Date Issued
October 1, 2009
Series/Report no.
ICAT;2009-04
Abstract
To improve capacity and efficiency of the air transportation system, a number of new systems-level
changes have been proposed. Key aspects of the proposed changes are combined
functionality across technology and procedures and large physical scale of deployment. The
objective of this work is to examine the current safety assessment processes for systems-level
changes and to develop an understanding of key challenges and implications for the assessment
and approval of future systems-level changes.
From an investigation of current U.S. and international safety regulatory policies and processes,
a general model was created describing key processes supporting operational approval. Within
this model, a framework defined as an influence matrix was developed to analyze key decisions
regarding the required scope of analysis in safety assessment. The influence matrix represents
the expected change in levels of risk due to changes in behavior of elements of a system. It is
used to evaluate the appropriate scope of analysis in safety assessment. Three approaches to
performing safety assessment of systems-level changes were analyzed using the framework: the
risk matrix approach, target level of safety approach, and performance-based approach. Case
studies were performed using eight implemented and pending systems-level changes.
In this work, challenges expected in safety assessment of future systems-level changes were
identified. Challenges include the large scope of proposed changes, which drives a need for a
broad and deep scope of analysis, including the multiple hazards and conditions and complex
interactions between components of a change and the external system. In addition, it can be
expected that high safety expectations will increase the required accuracy of models and
underlying data used in safety assessment. Fundamentally new operational concepts are also
expected to expand the required scope of safety assessment, and a need to interface with legacy
systems will limit achievable operations. The large scope of analysis expected for future
changes will require new methods to manage scope of safety assessment, and insights into
potential approaches are discussed.
Subjects
systems-level
safety assesment
air transportation
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