High-Flying Concepts: Understanding ARP4761A and the Aviation Safety Assessment Process

In one of our previous blogs about Dependant Failure Analysis, we have opened up the topic of crossover between aviation and automotive safety processes. This time, we are taking it a step further in aviation direction, unpacking the safety assessment approach behind ARP4761A and exploring the core concepts that ensure smooth operations.

Why aviation leads in safety

Aviation is acknowledged as one of the safest forms of transportation. This reputation is the result of decades of rigorous regulation and proactive safety management. It is committed to continuous improvement.

Every aspect of aviation is a subject to safety assessment, the primary objective of which is to uncover and evaluate potential hazards. This in turn enables the prevention of these hazards, or at least their detection and/or mitigation, ensuring the protection of aircraft, crew and passengers.

The building blocks of aviation safety assessment

A safety assessment in aviation is a systematic scrutiny which includes:

• analysis of functions and architectural design;
• allocation of a development assurance level (DAL);
• selection of components;
• application of appropriate mitigation techniques;
• monitoring;
• maintenance, and
• configuration control throughout the operational life of the system.

Only by executing a comprehensive and iterative safety assessment process aligned with industry standards, we can ensure development that complies with the necessary safety–related requirement.

ARP4754B and ARP4761A: The Cornerstones of Modern Aviation Safety

Two key SAE International documents lie at the heart of state-of-the-art safety assessment methodologies in aviation:

• ARP4754B: Guidelines for the Development of Civil Aircraft and Systems, providing a framework for system-level development;

• ARP4761A, Guidelines and Methods for Conducting the Safety Assessment Process on Civil Airborne Systems and Equipment which outlines the detailed safety assessment methods used to identify hazards, analyse risks, and verify compliance with safety objectives.

Neither document is a regulatory standard with mandatory requirements. Rather, they are recommended practices that provide guidance for safety regimens and support for the certification process of aircraft and systems under regulatory standards (such as EASA CS-25 and FAA FAR Part 25).

Six Phases of Safety Assessment in ARP4761A

ARP4761, published in December 1996, defined the foundation of aircraft safety assessment and was widely used. However, aviation technology and certification practices have evolved significantly since then. ARP4761A was published by the end of 2023, designed to reflect modern aircraft systems and development approaches.