Delineating the History, Purpose, and Current Context of Avionics Safety

As the aviation industry looks to recover, safety is again – and as alway, paramount. ARP4761A aviation safety assessments and protocols have illustrated that the concept of avionics safety does not rely on magic numbers, luck, or any sort of ‘’good fortune’’, but rather on calculated and quantifiable answers.

Following the same line of reasoning, Safety should never be categorised as an accident, but efficacious Safety should indubitably prevent accidents from happening.

In the very old days- of space shuttles, commercial jets with four engines, moon landings, etc, the principle of aircraft safety was predominately addressed using brains and refinement. Capable engineers proactively took measures to prevent any accident from happening, and- where those measures were unsuccessful, a corrective refinement process was followed .

Back then, however, computer horsepower was a lot less powerful than it is today, and engineers’ schedules were a lot ‘fatter’. Despite this, aircraft safety was generally quite successful- with space shuttles having an 98.5% chance of not exploding and commercial aircraft vehicles experiencing fatal crashes only a couple of times per annum.

‘’As the times started to change, the ‘’very old ways’’ didn’t work as well anymore. Field critics argued that engineers were not smart enough to be solely responsible for aviation safety, whilst others brought forth concerns of computers eventually becoming too smart’’- Vance Hilderman, Founder and Current CEO of AFuzion.

There was a widely accepted consensus that a much more ‘’formalized’’ safety procedure should be mandated, and thus the creation of SAE ARP4754 was published in late 1996.

It’s sibling ARP4761 (Guidelines and Methods for Conducting the Safety Assessment Process on Civil Airborne Systems and Equipment) was published a month later, in December 1996.

Below we will discuss the findings of a recent whitepaper released by AFuzion- a leading boutique company that specialises in aviation safety consultancy, which delineates the origins and purpose of ARP4754A.

ARP4754A Today: An Analysis

The amended version of the ARP4754A is officially titled ‘’Guidelines for Development of Civil Aircraft And Systems’’ and it viscerally covers all the development cycle for avionics and aircraft systems.

There are two main points that should be understood before even starting to open the pages of ARP4754A according to Vance.

Firstly, despite the title incorporating the world ‘’guidelines’’, this should in no way be interpreted so as to suggest that there is an element of subjectivity; not complying with ARP4754A protocols may reduce safety and will greatly reduce your chances to achieve certification. 

Secondly, as a result of a plethora of organisations previously treating ARP4754- ARP4754A’s predecessor, as ‘’optional’’, current certification organisations worldwide are beginning to formally mandate compliance with the latest version (ARP4754A). 

‘’For experienced, proficient developers…ARP4754A reads like a book for maintaining a good personal health: make a plan for health, understand healthy living, be safe, eat well, reduce stress, sleep, get regular check-ups to prove you followed your health plan, and repeat’’- explains Vance.

ARP4754A: Purpose

Before exploring the complexities and specifics of ARP4754A, you should first understand why it was initially created, and why it still exists.

A couple of decades ago- when avionics systems were a lot more simple and uncomplicated in nature, it was much easier for engineers to conceive safety systems entirely mentally and instantly proceed with the implementation process. Today, however, the variety, number, and complexity of systems has continued to proliferate exponentially.

Indubitably, the sphere of avionics is a lot more specialised and complicated than commercial brick and mortar buildings, but it would be considered completely unreasonable to begin building a commercial building without first conducting a thorough: foundation design, earthquake analysis, and plan for all of the inspections that will follow.

Of course, it is likely that among the best builders in the world, some do exist that could safely build a property without any blueprints, detailed plans, and inspections, but allowing for such an exception would mean that there would be no ‘’standardised’’ and accepted way to fully verify the building’s greatness in a safety context.

Suggested Video for you by Afuzion:

Final Words: The Original ARP4754

As briefly touched on above, the original ARP4754 standard was initially published in 1996; its main purpose was to assist avionics development organisations and enable them to think beyond bare software and hardware.

DO-178 (and its European alternative ED-12) was in fact published over a decade prior to 1996 so as to provide sufficient guidelines in the sphere of avionics software.

By the early 1990s, it was unequivocally clear that both safe software and safe certification required knowledge of both: a) confirmation of system level safety aspects, and b) holistic knowledge of the system.

ARP4754 was primarily focused on all aircraft system failures that could reasonably be predicted to significantly affect the safety of an aircraft or of its occupants.

ARP4754 is actually not concerned with specific components of the aircraft, but rather with entire systems. These generally have very complicated and specialised interactions with other systems on and off the aircraft, and consequently tend to evolve significantly over time- as they are developed by a plethora of different persons. 

 ARP4754, therefore, was seen as the best means of ensuring the implementation of safe, standardized codified development processes which were based upon deterministic safety.