Quantitative safety assessment of air traffic control systems through system control capacity

Jingjing Guo, Purdue University

Abstract

Quantitative Safety Assessments (QSA) are essential to safety benefit verification and regulations of developmental changes in safety critical systems like the Air Traffic Control (ATC) systems. Effectiveness of the assessments is particularly desirable today in the safe implementations of revolutionary ATC overhauls like NextGen and SESAR. QSA of ATC systems are however challenged by system complexity and lack of accident data. Extending from the idea “safety is a control problem” in the literature, this research proposes to assess system safety from the control perspective, through quantifying a system’s “control capacity”. A system’s safety performance correlates to this “control capacity” in the control of “safety critical processes”. To examine this idea in QSA of the ATC systems, a Control-capacity Based Safety Assessment Framework (CBSAF) is developed which includes two control capacity metrics and a procedural method. The two metrics are Probabilistic System Control-capacity (PSC) and Temporal System Control-capacity (TSC); each addresses an aspect of a system’s control capacity. And the procedural method consists three general stages: I) identification of safety critical processes, II) development of system control models and III) evaluation of system control capacity. The CBSAF was tested in two case studies. The first one assesses an en-route collision avoidance scenario and compares three hypothetical configurations. The CBSAF was able to capture the uncoordinated behavior between two means of control, as was observed in a historic midair collision accident. The second case study compares CBSAF with an existing risk based QSA method in assessing the safety benefits of introducing a runway incursion alert system. Similar conclusions are reached between the two methods, while the CBSAF has the advantage of simplicity and provides a new control-based perspective and interpretation to the assessments. The case studies are intended to investigate the potential and demonstrate the utilities of CBSAF and are not intended for thorough studies of collision avoidance and runway incursions safety, which are extremely challenging problems. Further development and thorough validations are required to allow CBSAF to reach implementation phases, e.g. addressing the issues of limited scalability and subjectivity.

Degree

Ph.D.

Advisors

Marais, Purdue University.

Subject Area

Aerospace engineering|Systems science

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