STANAG 4671 compliance matrix for a military UAS: AEP-4671

A STANAG 4671 compliance matrix is the table that lists every applicable paragraph of the Unmanned Aircraft Systems Airworthiness Requirements, the USAR published as AEP-4671, states whether and how each applies to the aircraft, names the means of compliance and points to the compliance document that carries the evidence. In a European military programme it sits inside the certification programme that EMAR 21.A.15(b) requires, and its rows come from a certification basis the national military airworthiness authority establishes under EMAR 21.B.80, usually by tailoring the EMACC criteria and designating the USAR. This guide explains what the standard is, how the basis is built, the columns and seven steps that produce a matrix the programme can be run from, and which of those steps an AI teammate can draft. It quotes no USAR text: the AEP is published by the NATO Standardization Office and your programme works from the edition your nation ratified.

What STANAG 4671 is

STANAG 4671 is the NATO standardization agreement for the airworthiness of military unmanned aircraft systems. The NATO Standardization Office lists Edition 3 as promulgated on 2 April 2019, non classified, with the Joint Capability Group on Unmanned Aircraft Systems as its sponsor, and records one covered standard: AEP-4671 Edition B Version 1, "Unmanned Aircraft Systems Airworthiness Requirements (USAR)". The agreement is the political instrument; the AEP holds the requirements. The first edition was issued in September 2009, and the EDA's EMACC Guidebook describes how it was built: from EASA CS-23, supplemented by the JAA and Eurocontrol UAV Task Force report, the Italian RAI-UAV standard, the Australian UAV design standards, Defence Standard 00-970 Part 9 and the USICO stall demonstration review item.

The same guidebook states the scope: fixed-wing military unmanned aircraft with a maximum take-off mass between 150 kg and 20,000 kg, with the aim of a level of airworthiness design equivalent to manned general aviation aircraft that fly in all classes of airspace under VFR and IFR. Three kinds of difference from CS-23 matter to the matrix. Paragraphs for configurations that unmanned aircraft do not have, such as skis, amphibians and seaplanes, were removed. Paragraphs for the utility, aerobatic and commuter categories were removed. Paragraphs were added for features CS-23 aircraft do not have, above all the command and control data link and its loss strategy, and automatic take-off and landing. The numbering follows CS-23, so that the EMACC cross-references read as 4671.1309 or 4671.601, with the added unmanned-specific paragraphs carrying a U prefix, such as 4671.U1703.

One caution comes before any row is written. The EMACC Handbook says that with respect to the cross-referencing of NATO STANAGs, nations should examine their ratification status for each STANAG before assuming the document applies. A ratification can carry reservations that modify paragraphs for that nation's programmes. The matrix header must name the edition and the ratification status, and the rows must reflect the reservations.

Where the matrix sits: EMAR 21

EMAR 21 is the European Military Airworthiness Requirement for certification of military aircraft and for design and production organisations, developed by the Military Airworthiness Authorities Forum under the European Defence Agency and adopted into national military regulation by the participating nations. Edition 2.0 was approved on 30 March 2021 and its AMC and GM Edition 2.0 on 4 October 2022. Its Section A follows EASA Part 21 point by point, so that an engineer who knows 21.A.15 and 21.A.20 in the civil rule will recognise them here, with military additions where they are needed.

The military additions are visible in the AMC. The list of kinds of operation under 21.A.15(b)(3) includes air-to-air refuelling, low-level flight, ship-based operations and the carriage or release of weapons and stores, and each of them can bring EMACC criteria into the basis that CS-23 never contained. Under 21.A.15(b)(4) the AMC adds a sentence that has no civil counterpart: when the certification basis is established using EMACC, the justification for the de-selection of criteria and for the mapping of specific requirements to each selected criterion shall be documented. That sentence is what makes a military matrix wider than a civil one, because it needs a column for the tailoring.

Building the basis from EMACC

The EMACC Handbook, Edition 3.1 of September 2018, states its purpose as establishing the airworthiness certification criteria to be used in determining the airworthiness of all manned and unmanned, fixed and rotary wing aircraft systems, as a foundational document for the authority to define the certification basis. Each criterion is a paragraph of engineering intent with considerations and a block of information sources: 14 CFR paragraphs, EASA CS paragraphs, Defence Standard 00-970 references and STANAG paragraphs. For a military UAS the STANAG column points into AEP-4671, and the handbook's own caution applies: the references are a guide, not a substitute for citing the requirement.

Section 1.2.1 sets four tailoring rules that the matrix has to show it followed. Identify each criterion as applicable or not, considering complexity, type, data and intended use, and document the rationale for any non-applicable finding. Do not delete applicable criteria; where a portion does not apply or is modified, identify the applicable and non-applicable portions and the modification, and document the rationale, keeping the intent and context. Supplement applicable criteria with specific measurable parameters where they add value. Develop additional criteria for capabilities or systems the handbook does not fully address. The handbook adds that tailoring is not an exercise intended to relax the criteria, that for military operations it may produce a more demanding basis, and that the basis should be built top-down so that the effect of one system on others is captured. The Guidebook's worked example shows the mechanics: for EMACC criterion 13.1.2 on the electromagnetic environmental effects of non-flight-critical equipment, applied to a new video system on a UAS, it selects STANAG 4671 as the airworthiness code and lists the USAR paragraphs, some CS-23 derived and some U-prefixed, that carry the requirement.

The columns of a military matrix

The civil columns stay. The military basis adds three.

• Requirement reference, with the AEP-4671 edition and the national ratification reference in the header; special conditions and EMACC-derived requirements numbered in the same series.
• EMACC criterion, the handbook section the row traces to, so that the top-down tailoring can be audited from the criterion to the USAR paragraph and back.
• Tailoring status and rationale, as applicable, not applicable, partially applicable or modified, with the justification EMAR AMC 21.A.15(b) requires, separate from the applicability rationale for the design.
• National reservation, where a reservation touches the row, with the reference.
• Applicability against the type design and the kinds of operation, with its rationale.
• Means of compliance, as MC codes, and the compliance demonstration item with its novelty, complexity and criticality flags.
• Compliance document, by number and issue, and owner and status with a column for the authority's findings.

Seven steps to build the matrix

1. Confirm the edition and the national ratification status. Record which edition of STANAG 4671 and AEP-4671 the authority has designated, and how your nation ratified it, with any reservation. The EMACC Handbook warns that nations should examine their ratification status for each STANAG before assuming it applies, and a reservation can change or remove paragraphs for your programme. Put the edition, the ratification reference and the reservations in the header of the matrix before the first row.
2. Agree the certification basis with the authority. Under EMAR 21.B.80 the authority establishes the type-certification basis and notifies it to the applicant: the airworthiness codes designated at the date of application, any special condition under 21.B.75, and dedicated requirements established by tailoring the EMACC criteria for products or kinds of operation the codes do not cover. Your proposal under 21.A.15(b)(4) is what the authority works from, so submit it with the USAR paragraphs, the EMACC criteria and the tailoring justification already written down.
3. Enumerate the USAR down to the lettered sub-paragraph. One row per paragraph and sub-paragraph of AEP-4671 at the designated edition, including the paragraphs the USAR added for unmanned systems and any paragraph a national reservation modifies. Section headings are not rows. Where the basis also carries EMACC criteria or a special condition, give them rows in the same series so that the matrix has one requirement list, not three.
4. Decide applicability and write the rationale, including the tailoring. Mark each row applicable, not applicable or partially applicable against the type design description and the kind of operations under 21.A.15(b)(1) to (3). EMAR AMC 21.A.15(b) requires that, where the certification basis is built with EMACC, the justification for de-selecting criteria and for mapping requirements to each selected criterion is documented; the EMACC tailoring rules add that applicable criteria may not be deleted and that a modified criterion keeps its intent. The rationale column is where both live.
5. Assign the means of compliance and group the rows into compliance demonstration items. Give each applicable row one or more codes from the Appendix to EMAR AMC 21.A.15(b), MC0 to MC9, the same codes EASA uses. Group related rows into compliance demonstration items under 21.A.15(b)(5) and state, for each item, the novelty, complexity and criticality information the authority needs to set its level of involvement under 21.A.15(b)(6) and 21.B.100.
6. Link every row to a numbered compliance document. Under EMAR 21.A.20(c) the applicant records the justification of compliance within the compliance documents referred to in the certification programme. Reference each document by number and issue on the row it supports. A row that carries a code and no document number is an open item; the matrix is the register that shows where the programme still has open items.
7. Keep the matrix current and close it with the declaration. EMAR 21.A.15(c) requires the certification programme to be updated when the project changes any of its seven elements, and 21.A.20(b) requires the applicant to report difficulties that affect the risk assessment or the programme. When every row is closed, including the inspections and tests under 21.A.33 and the flight tests under 21.A.35, the applicant declares under 21.A.20(d) that compliance has been demonstrated and that no feature makes the product unsafe for its intended uses, and submits the declaration under 21.A.20(e).

What AI can draft and what the engineer decides

The mechanical part of a military matrix is larger than a civil one, because the basis has three sources and the tailoring has to be traced in both directions. That is work a language model does well when it works only from the designated edition of the AEP, the EMACC criteria, the special conditions and the type design description, and cites the paragraph behind every proposal. The judgement, and the declaration, stay with people.

Two conditions are specific to military work. The corpus the AI teammate answers from has to be limited to what the programme is cleared to hold, and it has to run where the programme's data may go, which for most military design organisations means on their own hardware with no outbound connection; the guide on on-premise and air-gapped AI covers what that requires. The general conditions are the ones in Can AI be trusted for aviation compliance documentation?: a controlled corpus at the right edition, citations at paragraph level, a boundary on who can change the corpus, and a review record. The civil counterpart of this guide, for EASA Part 21 and the FAA, is the guide on the certification-basis compliance matrix.

Five mistakes that produce findings

• A basis with no ratification reference. The rows follow the AEP as published, and the nation's reservation has modified two of the paragraphs the design relies on. Record the ratification status first.
• EMACC criteria de-selected without a written rationale. EMAR AMC 21.A.15(b) requires the justification to be documented, and the EMACC rules do not allow applicable criteria to be deleted. A blank tailoring column is a finding in itself.
• Three requirement lists instead of one. The USAR rows, the EMACC rows and the special conditions kept in separate tables with different numbering, so that nobody can show the basis is complete. One series, one matrix.
• Civil rows carried over unchanged. A CS-23 or SC Light-UAS matrix renamed for the military variant, with applicability decided for another operation and no rows for the data link, the control station or the kinds of operation the military AMC lists.
• A matrix that stops at the type-certification basis. EMAR 21.A.15(c) requires the programme to be updated when the project changes, and the declaration under 21.A.20(d) rests on the matrix as it stands on the day it is signed.

How Wingman360 Teammate builds one

The compliance-matrix workflow in Wingman360 Teammate starts from the designated edition of AEP-4671, the EMACC criteria, the special conditions and the type design description that the organisation's administrators have ingested, and from nothing else. It enumerates the requirements to sub-paragraph level in one series, proposes the tailoring mapping, the applicability and a means of compliance for each row with a citation into the source, and produces the matrix in the columns above for engineering review. Engineers accept, edit or reject every proposed row; the declaration of compliance is written and signed by the applicant. The same approved knowledge base answers questions during the programme, so the matrix and the answers share one controlled source. Each deployment is a dedicated single-tenant instance on the organisation's own hardware, offline where the programme requires it, with a local model so that no design data leaves the network. What else it drafts for a military UAS programme is on the UAS manufacturers and operators page, and for a military design organisation on the design and production organisations page.