International Journal of Mathematical, Engineering and Management Sciences

ISSN: 2455-7749

Sneak Circuit Analysis: Lessons Learned from Near Miss Event

James Li
Centre of Competence for Mass Transit, AME, Bombardier Transportation, Kingston, Canada.


Received on September 06, 2016
Accepted on October 24, 2016


Sneak Circuit Analysis is intended for critical applications which are essential to mission success and safety. A sneak condition will occur when a designed circuit inhibits a wanted function or results in an unwanted function. Sneak conditions originate from one of the four following scenarios: a sneak path resulting in a flow of electrical current along an unexpected route; a sneak timing that may cause the activation of some desired/designed functionality at an unexpected time; a sneak indication in monitoring functions that may result in an ambiguous or false display of system operating conditions; and lastly, a sneak label which may induce operator error due to inappropriate instruction. This paper introduces a near miss event that occurred in the Sao Paulo monorail which was caused by a sneak time condition. Root cause analysis and design modifications are also discussed in the paper.

Keywords- Sneak circuit analysis (SCA), Sneak timing, Door enable, Door inhibit, Propulsion enable.


Li, J. (2017). Sneak Circuit Analysis: Lessons Learned from Near Miss Event. International Journal of Mathematical, Engineering and Management Sciences, 2(1), 30-36.

Conflict of Interest



MIL-HDBK-338B, Electronic Reliability Handbook, Notice 2 (pp. 468-480). Air Force Research Laboratory Information Publishing, 2005.

MIL-HDBK-785B, Reliability Program for System and Equipment Development and Production (p. 37). Department of Defense Publishing, 1980.

RADC-TR-82-179, “Sneak Circuit Analysis Application Guidelines”, Rome Air Development Center (RADC) Technical Report, June 1982.

RADC-TR-89-223, “Sneak Circuit Analysis for the Common Man”, Rome Laboratory, 1989.

RADC-TR-90-109, “Integration of Sneak Circuit Analysis with Design”, Rome Laboratory, 1990.

Rankin, J. P., Origins, Application and extension of sneak circuit analysis on space projects Hazard Prevent. 33(2), 2nd Q, 24-30 (1997).

Scappaticci, A., Benson, R., Foley, D., & Kellner, D. (2016, January). Sneak circuit analysis: Lessons learned for beginners based on a successful application. In 2016 Annual Reliability and Maintainability Symposium (RAMS) (pp. 1-6). IEEE.

SCAT: Sneak Circuit Analysis Tool, Version 3.0, RL-TR-95-232.

Sneak Circuit Analysis Guideline for Electro-Mechanical Systems, NASA Practice No. PD-AP-1314, Oct, 1995.

System Reliability Toolkit (p. 577). Reliability Information Analysis Center (RIAC) and Data Analysis Center for Software (DACS) Publishing, 2005.

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