Start with the document's purpose
An avionics announcement can compress several documents into one reassuring sentence. The references may be accurate while leaving the reader uncertain about what actually happened. Before judging a software-assurance claim, establish which document does which job. FAA AC 00-69, issued on 21 July 2017, describes itself as complementary best-practice information for ED-12C/DO-178C and AC 20-115D. It explicitly distinguishes that information from guidance. Its topics include software change impact analysis, relationships between software components, and handling foreseeable errors during design.
That makes the circular useful for asking better questions about engineering work. Citing it identifies relevant practices; the citation alone does not establish that a particular product followed them.
Separate recognition from project evidence
AC 20-115D has a different role. It describes an acceptable means, among possible alternatives, of showing compliance with applicable airworthiness requirements for the software aspects of type certification or Technical Standard Order authorization. It is not itself a regulation; the FAA says anyone using its described means must follow the applicable provisions. The circular recognizes ED-12C/DO-178C alongside documents addressing software tools, model-based development, object-oriented technology and formal methods. Applicable supplements accompany the base document rather than operating independently.
For a reader, this suggests two separate questions: what assurance approach is being used, and what evidence shows its application to the claimed software? A list of document numbers answers only part of that inquiry.
Find the review behind the statement
FAA Order 8110.49A addresses the certification staff and designees involved in reviewing software. It discusses examination of development processes and associated records, and inspections that connect tested software and hardware configurations to the approved design. Those subjects help interpret milestone language. A review, a completed test campaign and an approval are descriptions of different activities. A public announcement is more informative when it names the relevant activity, the configuration concerned and the organization making the determination.
Readers do not need access to every engineering record to notice this distinction. A statement that identifies a completed review and its scope offers a clearer basis for assessment than an unexplained claim of meeting aviation standards.
Keep the article and installation in view
The FAA's Technical Standard Order explanation provides a concrete example of scope. A TSO defines minimum performance criteria for a type of article. A TSO authorization includes design and production approval for that article; it does not by itself approve installation and use on an aircraft. The FAA explains that installation needs a separate approval addressing the particular aircraft's requirements. This matters when a supplier announcement moves from an approved component to a broad claim about a complete platform.
For defense-industry readers, the editorial question remains specific: which authority, product and approval basis does this announcement identify? A civil aviation reference by itself does not answer that question for an unnamed defense project.
Read a claim as a chain of evidence
Consider a hypothetical announcement saying that a new avionics software release draws on AC 00-69 and DO-178C. There is useful information in those references, but the statement leaves several things open: which release, which functions, what work was completed and what outcome was recorded. Our reading approach is to follow the chain from the document's role to the project activity and then to the evidence supporting the stated result. This is a way to interpret public claims, not a substitute for a project's certification process.
Ask three questions: Is the document being used as supplementary information or as part of the stated assurance approach? What specific software and configuration does the claim cover? Does the announcement describe work underway, completed verification or an authority's decision?
This explainer interprets the stated roles and scope of public FAA documents. Its hypothetical announcement is illustrative; it does not assess a named product or determine a project's certification basis.
Read the evidence.
- 01AC 00-69 — Best Practices for Airborne Software Development AssuranceFederal Aviation Administration · 21 Jul 2017
- 02AC 20-115D — Airborne Software Development AssuranceFederal Aviation Administration · 21 Jul 2017
- 03Order 8110.49A — Software Approval GuidelinesFederal Aviation Administration · 29 Mar 2018
- 04Technical Standard Orders: article authorization and installationFederal Aviation Administration