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Functional Safety - Overview of ISO 26262

Updated: 4 days ago

What is ISO 26262?


ISO 26262 is an international standard for the functional safety of electrical and electronic (E/E) systems in road vehicles. It ensures that E/E systems in road vehicle - cars, trucks, and motorcycles remain safe even when faults occur. The standard defines a risk-based approach using Automotive Safety Integrity Levels (ASILs) to classify hazards, evaluate the risk of hazards, and methods to mitigate risks - from concept and design to production, operation, and decommissioning.


The ISO 26262 standard is structured around three key aspects.

  • Organizational aspect - It outlines what an organization/company, as a whole, should do to ensure safety.

  • Technical aspect - This focuses on how to achieve safety in the product itself, and what technical solutions can be implemented to make the product safe.

  • Process aspect - This defines the processes that should be followed to maintain functional safety.


What are the contents of ISO 26262


The ISO 26262 standard is divided into 12 chapters, each chapter focusing on a different aspect of product development. Below is a breakdown of each chapter.

Part​

Title​

Summary​

Part 1​

Vocabulary​

This chapter defines key terms and abbreviations for consistent understanding throughout the standard.​

Part 2​

Management of Functional Safety​

This chapter explains how to plan, coordinate, and manage functional safety across the entire vehicle lifecycle. It also describes what an organization needs to do to ensure good safety culture​

Part 3​

Concept Phase​

This chapter is the beginning of the technical work for a project. It explains how to perform an Item Definition, Hazard Analysis and Risk Assessment (HARA), creation of safety goals and the functional safety concept (FSC).​

Part 4​

Product Development at System Level​

This chapter covers derivation of Technical Safety Concept and system architecture design. It also provides insights on what type of safety analyses has to be performed - Inductive analyses (e.g. Failure Mode Effect Analysis) and Deductive Analysis (e.g. Fault Tree Analysis)​

Part 5​

Product Development at Hardware Level​

Chapter 5 details hardware design, safety analysis, and verification activities to meet safety requirements. It also describes how certain hardware architectural metrics can be calculated. Some of the commonly used hardware architectural metrics include - Probabilistic Metrics for Hardware Failure (PMHF), Single Point Failure Metric (SPFM), Latent Failure Metric (LFM).​-

Part 6​

Product Development at Software Level​

This chapter specifies software development, design, and verification processes for safety-related systems.​

Part 7​

Production, Operation, Service, and Decommissioning​

This chapter ensures safety is maintained during manufacturing, operation, maintenance, and decommissioning.​

Part 8​

Supporting Processes​

Chapter 8 defines supporting activities such as configuration management, change control, and tool qualification.​

Part 9​

ASIL-Oriented and Safety Analyses​

Chapter 9 describes ASIL determination, decomposition, and safety analysis methods like FMEA and FTA.​

Part 10​

Guidelines on ISO 26262​

This chapter provides practical guidance and examples for consistent interpretation and application of the standard. - Examples of HARA, Hardware metrics like PMHF, SPFM, and LFM.​

Part 11​

Guidelines on Semiconductors​

This chapter adapts ISO 26262 for semiconductor components and integrated circuit development. It provides examples for Dependent Failure Analysis (DFA), fault models and safety mechanisms for semiconductor components like memory, programmable logic devices (PLDs) etc. ​

Part 12​

Adaptation for Motorcycles​

This chapter tailors ISO 26262 processes and terminology for motorcycle applications. It introduces the concept of MSIL (Motorcycle Safety Integrity Level) and the equivalence between ASIL and MSIL. ​



What should Safety engineers/ managers focus on?


As a new safety engineer, ISO 26262 can feel intimidating. The standard is large and often written in vague language. Here’s a concise cheat sheet highlighting what engineers can focus on:

  • System Safety Engineers: Focus on Chapters 3, 4, 7, and 8.

  • Software Safety Engineers: Focus on Chapters 6 and 8.

  • Hardware Safety Engineers: Focus on Chapters 5, 8, and 11.

  • Motorcycle / Two-Wheeler Applications: Focus on Chapter 12.

  • Safety Managers / Leads: Should have a solid understanding of all chapters and associated work products to effectively plan and execute safety activities.


This breakdown helps new engineers prioritize their niche and work while navigating the full ISO 26262 standard.


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