Overarching Properties

The Overarching Properties initiative seeks to provide flexibility and efficiency in the certification process. “Overarching Properties,” previously known as “Meta Objectives working group,” was first publicly discussed at the 2016 FAA “Streamlining Assurance Processes Workshop.”

What is the “Overarching Properties” initiative?

The Overarching Properties initiative seeks to provide flexibility and efficiency in the certification process across multiple levels of aircraft system design and disciplines. The FAA first discussed this publicly at the 2016 FAA “Streamlining Assurance Processes Workshop.” Initially the team working on this were referred to as the “Meta Objectives Working Group.” After several meetings, the name evolved from Meta Objectives into Overarching Properties.

“Overarching Properties” is sort of an odd terms so let’s look at this one word at a time. The term “Overarching” implies that it is bigger in scope that just hardware, or software, or systems. The word “Properties” refers to the concepts that guide the development assurance processes. Thus, the result of this initiative is an overarching set of properties that teams can apply at all levels of their design to demonstrate compliance to safe airborne system development practices under CFR Title 14 Parts 23/25/27/29/31/33.

The Overarching Properties Initiative may substantially change the way compliant development is done. It could even potentially replace or at least substantially increase the flexibility of DO-178C, DO-254, ARP 4754A and other processes typically used today under the concept of aircraft certification.

Overarching Properties Committee

The committee forming the Overarching Properties Initiative consists of about 20 industry experts. The FAA explicitly invited Tammy Reeve to participate and she has been an active contributing member since its very first incarnation several years ago.  The initial idea behind the initiative was to provide an “alternative means of compliance” to DO-254, DO-178C, and ARP 4754A, such that at all levels of development, any team on any project could demonstrate compliance to a consistent set of development assurance objectives. (Of course the activities associated with meeting those objectives would vary depending on the program and level of design).

After a number of meetings involving much debate and lively discussion, the committee came up with three Overarching Properties that should be met at any/all levels of design. Each Overarching Property contains the following:

  • Statement capturing the property
  • Definition
  • Pre-requisites
  • Constraints
  • Assumptions

The initial rollout of this at the 2016 FAA “Streamlining Assurance Processes Workshop” was met with confusion and concern. The concerns were tied mostly to the issues of training, consistency, oversight, acceptance by other authorities, and actual cost savings.  The committee has continued fine tune their efforts.

Overarching Properties

As of November 2017, the three overarching properties are:

  1. Intent
  2. Correctness
  3. Acceptability

In the context of each property, the design team must meet certain criteria, such as planning, coverage, evidence, process assurance, configuration management/change control, and interaction with safety assessment.

In a shift from their initial indications, the FAA has clarified that their goal is to publish these overarching properties as a “means of compliance” similar to what exists for DO-178C, DO-254, and ARP4754A. The FAA now want this to be an “acceptable means” as opposed to an “alternative means” of compliance to the regulation.

Numerous non-USA certification authorities still have some reservations as to how they can recognize this new method within their regulatory process or if they can recognize it at all. This discrepancy between authorities creates the potential for significant technical differences with regard to certification across countries. Authorities must resolve discrepancies between certifying agencies before the FAA publishes Overarching Properties as policy.