ECSS-Q-TM-40-04 Part 1A and Part 2A: Sneak analysis

These Technical Memoranda replace the discontinued standards:



The aim of sneak analysis is to identify sneak circuits, i.e. unexpected paths for a flow of mass, energy, data or logical sequence that under certain conditions can initiate an undesired function or inhibit a desired function. Sneak circuits are not the result of failure, but are latent conditions, inadvertently designed into the system.
This Technical Memorandum establishes a procedure for performing sneak analysis and specifies the required output.
The Technical Memorandum is composed of two parts:

  • Part 1 (i.e. this document ECSS-Q-TM-40-04 – Sneak analysis – Methods and procedures) that contains the methods and procedures for performing sneak analysis;
  • Part 2 (i.e. the document ECSS-Q-TM-40-04 – Sneak analysis – Clue list) that contains a basic clue list to be used during sneak analysis.


This technical memorandum is applicable when the performance of sneak analysis is required by ECSS-Q-ST-40 or by the business agreement between the customer and the supplier.

Alternative sneak analysis procedures proposed by the supplier may be accepted by the customer provided that equivalence, for the intended application, with the one presented in this Technical Memorandum is shown by the supplier.
This Technical Memorandum may be tailored for the specific characteristic and constrains of a space project in conformance with ECSS-S-ST-00.


This document was re-confirmed by the ECSS Technical Authority on 7 December 2022.



These Technical memoranda support following ECSS Standard: ECSS-Q-ST-40C – Safety (6 March 2009).