AEP-2333 combat clothing performance and protective properties

What it is

AEP-2333, Combat Clothing Performance and Protective Properties and Trial Guidance, is a NATO Allied Engineering Publication (AEP). Edition A was promulgated in December 2021, replacing separate NATO material on waterproof clothing (the former STANAG 4364), arctic clothing (the former STANAG 4573) and the 1992 ACCP-01 heat-transfer methodology, now Annex A. Like every AEP, it is not a ratified agreement in its own right: it is covered by STANREC 2333, a Standardization Recommendation, so nations are invited to use it rather than obliged to ratify it.

A NATO recommendation, not a ratified agreement

The document is explicit about how much room a National Authority has. Its water-resistant clothing chapter states plainly that "NA may choose to apply other test methods and/or to define other pass/fail criteria" than the ones it recommends (clause 2.1), and the mechanical strength requirements repeat the same point: "As mechanical strength has an implication on weight and price, NA may decide to apply other requirements" (clause 2.8.3(c)). AEP-2333 reaches a manufacturer only when a National Authority's own tender or contract selects specific thresholds and test methods from it. Outside that contract, it functions as a shared reference nations draw on when writing their own procurement specifications, not a requirement in itself.

Six chapters, one climate and threat at a time

The document works through combat clothing by environment. Chapter 1 sets out the general Combat Clothing System: a "mix-and-match" layered system whose garments can be added or removed by activity and temperature (clause 1.6), with camouflage requirements matched to the background's infra-red reflectance, colour and luminance (clause 1.5), and a table of sixteen properties every candidate garment is measured against, including breathability, water resistance, thermal insulation, ultraviolet protection at a minimum factor of UPF 30, wear resistance (with a stated minimum service life of six to eight months of military use) and functionality. Chapter 2 covers water-resistant clothing, Chapter 3 tropical field clothing, and Chapter 4 extreme cold weather clothing across a range the document defines as "temperature variations between +10 °C and -50 °C" before wind-chill (clause 4.3). Chapter 1 states directly that the general Combat Clothing System "does not cover specialist clothing such as clothing for Armoured Fighting Vehicle crewmen etc." (clause 1.3(d)).

What the performance tables actually require

Chapter 2's water-resistant clothing tables are typical of how the document works: recommended thresholds for water penetration on fabric, cross seams and the whole garment, water-vapour resistance, mechanical strength (breaking load, tear strength, abrasion cycles), dimensional change (not exceeding plus-or-minus 3 percent after five wash or dry-cleaning cycles, clause 2.8.4) and resistance to delamination, each tested new and after specified wash, dry-cleaning, flex and contamination pre-treatments. The test methods named are almost all civil textile standards obtained from their own publishers, chiefly ISO (ISO 811, ISO 4920, ISO 11092, ISO 13935-2, ISO 12947-2, ISO 4674-1, ISO 1421, ISO 3175-2, ISO 9865, ISO 6330, ISO 5077, ISO 7854) with DIN 53359 and EN 14360 alongside them. Tropical field clothing (Chapter 3) has to protect "to enable use in a UV index 11+ environment" (clause 3.4(d)) while staying lightweight, air-permeable and fast-drying. Extreme cold weather clothing (Chapter 4) is a multi-layer system, underwear, middle layer, outer garment, mittens, headgear and eye protection, each with its own characteristics, referencing ISO 11079 for assessing cold stress and required clothing insulation.

Flame and heat protection for mounted and dismounted personnel

Chapter 5 addresses flame resistant clothing for both dismounted soldiers and mounted personnel such as combat vehicle crews and helicopter crews (clause 5.3), against threats from burning fuel, exploding ammunition, vehicle penetration and improvised explosive devices. Outer-layer fabric should self-extinguish when tested to ISO 15025 or ASTM D6413 (clause 5.8(b)(1)), and complete garments should be tested by instrumented manikin to ISO 13506 or ASTM F1930 with a 3-second flame-exposure threshold and a 5-second objective, after which "the predicted burn injury (2nd and 3rd degree) should not exceed 35% of the manikin body area" (clause 5.8(b)(3)). Thermal shrinkage measured to ISO 17493 "should not exceed 10%" (clause 5.8(b)(4)). Design details such as covering fasteners, keeping metal off the skin, and tucking layers into each other are specified to limit chimney effects and skin exposure at the neck, wrists and ankles.

Troop trials before large-scale fielding

Chapter 6 is a separate discipline from the performance tables: guidance on running user evaluations of clothing and equipment before large-scale fielding. It describes four types of trial (laboratory, controlled field, uncontrolled field and operational, clause 6.5) suited to different project stages, and requires linking any evaluation to a Statement of Requirements through a Pattern of Analysis (clause 6.8). Trials involving people need ethics review: "Typically ethical reviews shall occur prior to the beginning of any field trial, and usually involve the collection of informed consent from trial participants" (clause 6.6(b)). Sampling ranges from five to ten hand-selected users per size category for a fitting trial up to twenty to thirty for a broader human-factors trial (clause 6.7(c)). Annex A, the revised 1992 ACCP-01, supplies the underlying science: a four-stage evaluation programme and the equations used to predict a clothing ensemble's thermal resistance, water-vapour resistance and effect on the wearer, including a note that the commonly used Pandolf load-carriage equation "under-predicts the metabolic rate of contemporary military load carriage" (Annex A, paragraph 9.8).

What auditors and buyers actually look for

AEP-2333 names no accredited certification body and no NATO-run scheme for certifying combat clothing against it. Compliance is checked by whichever National Authority is procuring the clothing, against the test methods and pass/fail thresholds that authority has chosen from the document, since both clause 2.1 and clause 2.8.3(c) let it substitute its own. A reviewer working from this document should expect to see test reports for each individual property in Table 2, not a single blanket compliance statement, and should expect the specific thresholds actually in force to be named in the contract rather than assumed from the AEP itself.

Standards it references

• STANAG 4370Background
• AECTP-230Background
• STANAG 4296Background