IWXXM
Summary of ICAO Meteorological Information Exchange Model (IWXXM)
IWXXM is an information model designed for the operational exchange of meteorological information for aviation. Expressed in Unified Modelling Language (UML), the logical model of IWXXM utilizes the Geography Markup Language (GML) defined by the Open Geospatial Consortium (OGC) to express geographical features of meteorological phenomena.
The XML/GML Schema serialized from the UML model, together with a set of Schematron Rules, constitute the official representation of meteorological information required by International Civil Aviation Organisation (ICAO) Annex 3 to the Convention on International Civil Aviation - Meteorological Service for International Air Navigation as well as Procedures for Air Navigation Services – Meteorology (PANS-MET) and is documented in the World Meteorological Organization (WMO) No. 306 Manual on Codes - International Codes, Volume I.3.
IWXXM includes representations for most of the reports in Annex 3 and PANS-MET, such as METAR/SPECI, TAF, SIGMET, AIRMET, Tropical Cyclone Advisory, Volcanic Ash Advisory, Space Weather Advisory, WAFS Significant Weather Forecast, Volcano Observatory Notice for Avition and Quantitative Volcanic Ash Concentration Information.
Unlike the Traditional Alphanumeric Code (TAC) forms of the ICAO Annex 3 and PANS-MET, IWXXM is not intended to be directly used by consumers like pilots. IWXXM is designed to be consumed by software acting on behalf of the consumers, such as display software.
References
- Manual on Codes (WMO-No. 306), Volume I.3. Part D - Representations derived from data models
- Manual on the Digital Exchange of Aeronautical Meteorological Information, ICAO Doc 10003
Latest release* of schema files
https://schemas.wmo.int/iwxxm/2025-2/
Package compatibility
The following table shows the versions of IWXXM and its individual packages (e.g. METAR/SPECI) and their relationships to ICAO Annex 3 requirements. If more than one version are indicated for an IWXXM report, it means the information model of the report has not been changed across the versions and either one of them can be used. After IWXXM 3.0, a new version scheme has been adopted in which individual package will maintain its own version number instead of inheriting the version number from IWXXM. This eliminates the need to advance the version number of a package with no apparent change with its schema.
| IWXXM Version | 1.1 | 2.1 | 3.0 | 2021-2 | 2023-1 | 2025-2 |
| METAR and SPECI | 1.1.0 | 2.1.1 | 3.0.0 | 3.1.0 | 3.1.0 | 3.2.0 |
| TAF | 1.1.0 | 2.1.1 | 3.0.0 | 3.0.1 | 3.0.1 | 3.0.2 |
| SIGMET | 1.1.0 | 2.1.1 | 3.0.0 | 4.0.0 | 4.0.1 | 4.0.2 |
| AIRMET | 2.1.1 | 3.0.0 | 3.1.0 | 3.1.1 | 3.1.2 | |
| Tropical Cyclone Advisory | 2.1.1 | 3.0.0 | 3.1.0 | 3.1.0 | 3.1.1 | |
| Volcanic Ash Advisory | 2.1.1 | 3.0.0 | 3.1.0 | 3.1.0 | 3.2.0 | |
| Space Weather Advisory | 3.0.0 | 3.0.1 | 3.0.1 | 3.1.0 | ||
| WAFS SIGWX Forecast | 1.0.0 | 1.1.0 | 1.2.0 | |||
| Quantitative Volcanic Ash Concentration Information | 1.0.0 | |||||
| Volcano Observatory Notice for Aviation | 1.0.0 | |||||
| ICAO Annex 3 Amendment | 76 | 77 | 78 | 79-80 | 79-81 | 82 |
| PANS-MET Edition | first |
*See the IWXXM release communication plan
WMO Abbreviated Headings and Related Specifications Relevant for the Exchange of Aviation Data over ICAO AFS
https://community.wmo.int/ahls-aviation-data-over-icao-afs
Development areas
- The IWXXM repository contains XML schema and schematron files.
- The IWXXM modelling repository contains UML model of IWXXM and tools that were used for preparing schemas, schematron rules and associated files in this repository.
- The IWXXM codelists repository contains code lists for use with IWXXM which are also uploaded to the WMO Codes Registry for online access.
- The IWXXM translation repository has resources related to Traditional Alphanumeric Code (TAC) to IWXXM translation, including equivalent TAC/IWXXM pairs and a list of translation software.
Connect
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This page was last updated on 26 November 2025