Automotive Safety Integrity Level

Also known as: ASIL

ASIL is a four-level risk classification scheme (ASIL A, B, C, D) defined in ISO 26262 for the functional safety of road vehicle electrical and electronic systems, adapted from the SIL concept in IEC 61508.

Last updated: April 2026

Key Facts

Term: Automotive Safety Integrity Level
Abbreviation: ASIL
Defined by: ISO 26262
Number of levels: Four (ASIL A, B, C, D) plus a non-safety QM level
Highest level: ASIL D
Lowest level: ASIL A
Determination method: Hazard Analysis and Risk Assessment (HARA)
Determination factors: Severity (S0 to S3), Exposure (E0 to E4), Controllability (C0 to C3)
Parent concept: Safety Integrity Level (SIL) under IEC 61508
Industry: Road vehicles (passenger cars, motorcycles, trucks, buses, semiconductors)

What is ASIL?

ASIL is determined through Hazard Analysis and Risk Assessment (HARA), which evaluates each potential vehicle-level hazard against three factors: Severity, Exposure, and Controllability. The combined assessment maps to one of four ASIL levels plus a QM level.

ASIL D corresponds to systems where malfunction could cause severe or fatal injury. ASIL A applies to lower-risk systems. The assigned ASIL determines the rigour of design, verification, and validation required by ISO 26262. Higher ASIL levels demand higher test coverage, mandatory traceability, and comprehensive documentation.

ASIL Levels and Typical Examples

ASIL	Risk Level	Typical Example	Rigour
QM	Quality Management (no safety requirement)	Interior lighting control	Standard quality processes
ASIL A	Lowest	Rear lights	Basic safety requirements
ASIL B	Low to medium	Headlights, brake lights	Informal modelling
ASIL C	Medium to high	Cruise control, partial brake loss	Semi-formal modelling, prototyping mandatory
ASIL D	Highest (life-threatening if malfunctioning)	ABS, electronic stability control, airbags, steering	Highest test coverage, mandatory traceability, semi-formal modelling highly recommended

How ASIL Differs from SIL

SIL (IEC 61508): Probabilistic targets across four levels. Used in process, machinery, rail.
ASIL (ISO 26262): Qualitative hazard analysis across four levels plus QM. Used in road vehicles only.
Mapping: ASIL D is broadly comparable to SIL 3 in rigour. ASIL A is comparable to SIL 1. The two are not formally interchangeable.

How Automotive Training Providers Deliver ASIL Workshops

Automotive training providers deliver ASIL determination and verification as a focused module within ISO 26262 curricula, often as a half-day to two-day workshop.

Practical instruction typically combines case studies from ADAS, powertrain, braking, and steering systems with hands-on HARA exercises. Delegates include functional safety engineers, system architects, hardware and software developers, and project leads at OEMs and tier suppliers. Providers run ASIL workshops as in-house corporate cohorts during product development phases and as public open-enrolment courses for individual practitioners. Delivery needs cohort scheduling tied to client project timelines, branded corporate portals, identity verification at exam, and verifiable certificates accepted by OEMs and certification bodies.

Common Questions

How is ASIL determined?

Through Hazard Analysis and Risk Assessment (HARA), which combines Severity, Exposure, and Controllability ratings into a single ASIL classification. Each safety goal inherits the ASIL of the hazard it addresses.

What is the difference between ASIL and SIL?

ASIL is the automotive equivalent of SIL, defined in ISO 26262. SIL (defined in IEC 61508) uses probabilistic targets and applies broadly. ASIL uses qualitative hazard analysis specific to vehicle scenarios. The two are computed differently and not formally interchangeable.

What does ASIL D require that ASIL B does not?

ASIL D mandates higher test coverage, traceability across requirements, semi-formal modelling, and executable validation through prototyping or simulation. ASIL B can rely on informal modelling. The cost and effort step between ASIL B and ASIL D is significant.

Who needs ASIL training?

Functional safety engineers, system architects, hardware and software developers, ADAS engineers, and assessors at automotive OEMs and tier suppliers. Most teams take ASIL training as part of broader ISO 26262 certification.