Software Design FMEA for Functional Safety Systems


Functional safety is important for safety critical applications in any industry where active monitoring is required on safety critical operations. The active monitors either prevents or mitigates the failure that causes safety goal violations of the system. The failures are categorised as Systematic failures and Random hardware failures. Software design failures come under the systematic failures. Software design failure mode effect analysis (SW DFMEA) identifies all possible failures of the software and its severity, occurrence and controllability, also computes risk priority number that helps in prioritise the failures that need to be handled at highest priority.

This document provides guidelines on how to identify software failure modes and perform failure mode effect analysis.


[ISO 26262:9- 8.1, 8.2]

The scope of this document is to provide process, and guidelines to perform software design failure mode effect analysis (safety analysis).

The objective software safety analysis is to analyse software failures that impact system safety and provide a mechanism to prevent the failure, mitigate the failure, or reduce the impact of failure on system safety.

The safety analysis also finds ineffectiveness of existing safety mechanisms in handling anomalies such as latent faults, multiple-point faults, common cause failures and cascading failures.

This document covers safety analysis for software failures appear in software development phase. It is called design failure mode effect analysis (DFMEA).

Note: This document prepared with the references ISO26262 and J1939.