AECTP-230 climatic conditions for defence materiel

What it is

AECTP-230, Climatic Conditions, is a NATO Allied Environmental Conditions and Test Publication. It is a catalogue of data, not a set of requirements in its own right: it describes the natural (meteorological) climatic conditions found worldwide and the induced conditions that transport, storage and a host platform add on top, identifies the damage each can cause, and gives advice on choosing a test method. A project uses it to write the climatic clauses of its own Environmental Requirements Document or Life Cycle Environmental Profile, and to pick test severities from its companion publication, AECTP-300. The current edition is Edition B, Version 1 (June 2025). It carries no technical change from the previous edition: the record of significant changes states that "no technical content within the AECTP-230 leaflets of Edition B Version 1 has been modified or changed," the changes being an updated introduction, a corrected table value, and refreshed climatic-category maps.

The Allied Environmental Conditions and Test Publications family

AECTP-230 is one of two documents carried by STANAG 4866, which is what gives it force among nations that ratify it: "the agreement of nations to use this publication is recorded in STANAG 4866." Its companion under that same STANAG is AECTP-300, which holds the test methods AECTP-230's data feeds. The wider AECTP family covers other environments the same way in pairs of a conditions document and a test document: mechanical conditions under STANAG 4867 (AECTP-240 and AECTP-400), and electrical and electromagnetic conditions under STANAG 4868 (AECTP-250 and AECTP-500). AECTP-230 and AECTP-300 were both previously carried by STANAG 4370, and AECTP-230 still says it "should be used in conjunction with STANAG 4370," which now carries the general environmental guidelines document AECTP-100.

The eight deployment contexts

Most of AECTP-230 is organised around where materiel physically sits, because that changes which climatic conditions actually reach it. After a general section on the mechanisms involved (temperature, humidity, air pressure, hydrostatic pressure, icing, dust and sand, wetting, and erosion by impact), separate leaflets work through transportation by road, rail, air and sea; handling and storage; man-mounted and portable equipment carried by troops; installation on land vehicles; deployment on aircraft, including the aerodynamic heating a supersonic weapon or high-speed aircraft skin experiences; deployment on ships and submarines; and air and surface weapons, from launch through free flight to target-activated systems such as mines. Each leaflet follows the same shape: what induced conditions occur there, what damage they cause, and which AECTP-300 test method and severity to select. The numbers are concrete and specific to context, for example a temperature of -21 °C to -57 °C assumed for parked materiel across the cold climatic categories, or 90 to 95 percent relative humidity assumed inside a conditioned aircraft compartment during descent into a tropical airfield.

The fourteen worldwide climatic categories

A separate part of the document (Section 2311, in three leaflets) defines fourteen climatic categories used throughout: three hot-dry land categories, three hot-humid land categories, five cold land categories, and three marine categories. For each one it gives a diurnal cycle of temperature, humidity and solar radiation recommended as a design criterion. For a hot category the design value is the temperature "attained or exceeded at the hotter locations in the category, on average, for a total time of approximately 7.4 hours (i.e., 1 percent of one month) during the hottest period of the year"; the cold categories use the mirror image of that same 1-percent-of-a-month definition. Each category also carries the highest or lowest value ever reliably recorded. A companion leaflet covers other factors that do not fit neatly into temperature and humidity: atmospheric pressure at altitude, ozone concentration, wind and gust speed, precipitation intensity, hail, ice accretion, snow load, and blowing sand and dust concentration.

Validating a test severity against your own data

Rather than only offering fixed fallback numbers, AECTP-230 also sets out a method (Section 2310) for an asset manager to turn their own field measurements into a defensible design or test value, using a statistical method based on recorded daily maxima. It is explicit about the limits of this: "it is not recommended that induced environments be calculated where less than five years of recorded data are available, and should not be calculated if less than one year of data are available." Where that data does not exist, the same section gives fallback induced diurnal cycles for every climatic category to use instead.

What a design reviewer or customer audit looks for

AECTP-230 names no certification, audit or inspection body, and it should never be described as something a supplier is "certified against." What actually gets checked later is whether a design was tested to the severities the project's own requirements document set, using the named AECTP-300 method, and whether that test record can be produced: the specific climatic category cited, the clause the severity came from, and the resulting test report. Whether that check is a government quality assurance surveillance, a design review, or a customer audit is set by the contract and the customer's quality clause, not by this document.

What it does not cover

AECTP-230 explicitly excludes climatic effects arising from accident, hostile action, or nuclear effects. Its own leaflets state that they "are not intended to be comprehensive," and the 2311 series states plainly that it does "not prescribe tests or trials schedules." Nowhere does the document set a pass or fail threshold: every severity is offered "where possible" or "in the absence of measured data," with specifically measured data from the actual application always the preferred source.

Standards it references

• STANAG 4370Background
• AECTP-100Background
• AECTP-600Background
• AECTP-300Background
• STANAG 4867Background
• AECTP-240Background
• AECTP-400Background
• STANAG 4868Background
• AECTP-250Background
• AECTP-500Background
• STANAG 2805Background
• STANAG 4194Background