ISO 26262-9:2018

Overview

ISO 26262-9:2018 - "Road vehicles - Functional safety - Part 9" defines the framework and requirements for Automotive Safety Integrity Level (ASIL)-oriented and safety-oriented analyses of safety‑related electrical/electronic (E/E) systems in series‑production road vehicles (excluding mopeds). It supports the ISO 26262 safety lifecycle by specifying how to analyse hazards, decompose requirements by ASIL, evaluate coexistence of elements, and identify dependent failures. The part is intended to be integrated into a company‑specific development framework and complements other ISO 26262 parts.

Key topics and technical requirements

• ASIL‑oriented analyses: Guidance on structuring safety analyses and tailoring requirements according to ASIL (automotive safety integrity level) assignments.
• Requirements decomposition: Methods to decompose system‑ and item‑level safety requirements while preserving ASIL targets and enabling ASIL tailoring.
• Criteria for coexistence of elements: Rules and examples for how multiple elements can coexist without violating ASIL assumptions.
• Analysis of dependent failures: Framework and recommended activities to identify and mitigate dependent and common‑cause failures between elements.
• Safety analyses: Expectations for safety analysis activities (inputs, prerequisites, work products) used across the safety lifecycle.
• Tailoring and integration: How to apply ISO 26262-9 when altering existing production systems or integrating systems developed outside ISO 26262 processes.
• Scope limitations: Focuses on hazards caused by malfunctioning behaviour of E/E systems; excludes unrelated hazards (electric shock, fire, toxicity, etc.) unless directly caused by E/E malfunction.
• Supplementary material: Informative Annexes (e.g., Annex A overview, example architectures, dependent‑failure framework) to support practical implementation.

Practical applications and users

Who uses ISO 26262‑9:

• Automotive functional safety engineers and system architects
• OEMs and suppliers designing safety‑related E/E systems
• Safety managers and safety assessors preparing compliance evidence
• Integration teams tailoring safety lifecycles for legacy or third‑party components
• Verification, validation and reliability engineers performing safety analysis

Typical uses:

• Performing ASIL decomposition from item to element level
• Documenting coexistence assumptions for integrated systems
• Conducting dependent‑failure and common‑cause failure analyses
• Tailoring safety activities when modifying production systems
• Preparing safety work products and evidence for audits and assessments

Related standards

• ISO 26262 series (other parts covering management, concept, system, hardware, software, validation)
• IEC 61508 (sector‑agnostic functional safety standard) - ISO 26262 adapts IEC 61508 principles for automotive use

Keywords: ISO 26262-9, ASIL, functional safety, automotive safety integrity level, E/E systems, safety lifecycle, dependent failures, requirements decomposition, safety analysis.