VAAC London Quantitative Volcanic Ash 1.0
Current JSON

Abstract

The Quantitative Volcanic Ash information service provided by the London Volcanic Ash Advisory Centre supplies meteorological gridded data and spatial polygon data in response to tailored API requests submitted by an end user. Data is provided under the remit of the International Civil Aviation Organisation (ICAO) and in accordance with ICAO Annex 3 – Meteorological Service for International Air Navigation and ICAO Doc 10157 PANS-MET – Procedures for Air Navigation Services – Meteorology.

Applications:

  • Volcanic ash hazard awareness and avoidance, for eruptions in the VAAC London area of responsibility (primarily Iceland);
  • Predicting dosages of Volcanic Ash for aircraft engine and airframe service scheduling.

Forecast data is available to download per unique volcanic eruption (for significant ash eruptions only) from two API endpoints, and organised in three collections:

1. The VAAC London QVA Gridded Data API provides two collections in netCDF format:

  • The probabilistic collection forecasts the likelihood of ash concentration exceeding four set thresholds in mg/m3: ≥0.2, ≥2.0, ≥5.0 and ≥10.0. It includes four separate datasets (one per threshold).
  • The deterministic collection forecasts the expected ash concentration as a deterministic gridded forecast for a specific timestep. It includes one dataset.

2. The VAAC London QVA Products API provides the ash polygon features in XML format as per the QVA IWXXM schema. Data consists of sets of polygons that represent the ash concentration when it exceeds each of the four following four thresholds in mg/m3: ≥0.2, ≥2.0, ≥5.0 and ≥10.0, where the ash plume is present in the atmospheric layer between FL000 and FL600. This collection has one dataset.

In addition, users can subscribe to receive notifications when new payloads are ready to collect from the APIs. Notifications are filtered based on 'topics’ to which they have subscribed.

Key features:

  • Adheres to the EUROCONTROL Technical Infrastructure Yellow Profile and the OGC-EDR framework.
  • Gridded data is accessible through its own API endpoints; IWXXM data is available through its own, separate API endpoints.
  • Metadata in JSON format at collection level relating to the description and operation of the APIs.
  • Both APIs can handle multiple different erupting volcanoes simultaneously, and each volcano is listed as a unique location within each collection.
  • Only the most recently published set of data for each volcano is available through the APIs.
  • Published data covers the period T+0 to T+24 at 3-hourly intervals.
  • 0.25-degree horizontal resolution gridded data sets. Gridded data is provided as 5000ft thick horizontal slices for FLs: 000-050, 050-100, 100-150, 150-200, 200-250, 250-300, 300-350, 350-400, 400-450, 450-500, 500-550, 550-600. 
  • IWXXM data includes vertical levels where the ash plume is present in the atmospheric layer between FL000 and FL600. 
  • Forecasts encompass the entire ash plume, however large and wherever it extends, for volcanic eruptions in the VAAC London area of responsibility (Iceland).

In the event of operational issues, from December 2025 the VAAC Toulouse Quantitative Volcanic Ash API service operated by Météo-France will provide backup.

The QVA service is available from 28 July 2025 for testing and set up, and for operational use from 27 November 2025.

Service Type
SWIM_COMPLIANT
Life Cycle
OPERATIONAL
Business Activity Type
AIRSPACE_ORGANISATION_AND_MANAGEMENT
Intended Consumer
AERONAUTICAL_INFORMATION_SERVICE_PROVIDER
AIR_TRAFFIC_SERVICE_PROVIDER
CIVIL_AIR_NAVIGATION_SERVICE_PROVIDER
CIVIL_AIRSPACE_USER
NETWORK_MANAGER
PROVIDER_OF_DATA_SERVICES
REGULATED_METEOROLOGICAL_SERVICE_PROVIDER
Information Exchange Category
AERONAUTICAL_INFORMATION_EXCHANGE
METEOROLOGICAL_INFORMATION_EXCHANGE
Application Message Exchange Pattern Entity
SYNCHRONOUS_REQUEST_REPLY
State ICAO Nationality Letters
EGRR
ICAO Region
EUR
In-Operation Date
28-Jul-2025
Provider
Met Office

The Met Office is the sole Air Navigation Service Provider (ANSP) certificated by the UK Civil Aviation Authority to provide and disseminate a range of aviation forecast products and services, in accordance with ICAO Annex 3 to the Chicago Convention, Meteorological Service for international Air Navigation.

ICAO’s Annex 3 provides the main regulatory framework against which the UK is obliged to provide meteorological services, and which the Met Office delivers Met Services against. This ensures that the UK meets its obligations to ICAO to provide safe, efficient and regular air travel.

These services fall into the following main categories:

a) UK services.

b) The World Area Forecast System (WAFS), as provided by World Area Forecast Centre (WAFC) London, in coordination with WAFC Washington.

c) SADIS (Secure Aviation Data Information Service).

d) The Volcanic Ash Advisory Centre (VAAC) London.

In addition to the ICAO Annex 3 determined services, a range of discretionary services that are determined as a requirement in the UK are also provided. Specific services such as Aviation R&D and the provision of information to NATS are examples of this.

Provider Type
REGULATED_METEOROLOGICAL_SERVICE_PROVIDER
Support

To report incidents on services in operation, contact the 24/7 Weather Desk at [email protected] or +44 330 135 0000

Point of Contact
Operational needs for the Quantitative Volcanic Ash Service

As part of its responsibilities as the London Volcanic Ash Advisory Centre (VAAC) the Met Office is required to provide services related to volcanic ash as defined in ICAO Annex 3 Meteorological Service for International Air Navigation, and from 27 November 2025 ICAO Doc 10157 PANS-MET – Procedures for Air Navigation Services – Meteorology

The requirement to provide Quantitative Volcanic Ash Forecasts (QVA) is introduced with Amendment 82 to Annex 3, applicable 27 November 2025.

Data type

Responses to API requests are formatted as either:  

- JSON. These describe the operation of the EDR API and the 'Collections’ which are available to download from the latest model update (which include a list of available datasets under each 'collection’ for the latest available model update).

- For the VAAC London QVA Gridded Data API, as NetCDF. These files contain the actual forecast data as grid points for the two gridded data collections:  

  • "qva_probabilistic": forecasts about the likelihood of ash concentration exceeding set thresholds (≥0.2, ≥2.0, ≥5.0 and ≥10.0 mg/m3)  
  • "qva_deterministic": forecasts about the expected ash concentration in mg/m3 as a deterministic gridded forecast.

- For the VAAC London QVA Products API, as IWXXM. These files contain the actual forecast data for the “qvaci_iwxxm” collection. It serves payloads in XML format as a set of polygons, each polygon representing the ash concentration when it exceeds set thresholds (≥0.2, ≥2.0, ≥5.0 and ≥10.0 mg/m3) for a specific timestep. 

All the data sets will be provided covering the period from T+0 hour to T+24 hours at 3-hourly intervals from the time they are issued and will be updated every 6 hours while a significant ash cloud remains.

OAUTH2 Client Credential/Bearer Token

Accessing the service is subject to prior approval by the VAAC London Manager and agreeing to our terms and conditions. 

Access is based on OAUTH2 Client Credentials using Client ID and Secret to retrieve a Bearer Token. Login credentials must be set up days in advance of first-time use.

Access to the two VAAC London's Quantitative Volcanic Ash APIs does NOT include reciprocal access to VAAC Toulouse QVA service, operated by Météo France. Should you wish to access VAAC Toulouse QVA service, then you must apply directly with Météo-France.

Check Headers

The QVA APIs make use of standard HTTP headers, as specified in the SWIM Yellow Profile, WS Light Service Interface Binding.

Service Consumption Constraint

Usage is limited as per our throttling standard policies:

  • For the VAAC London QVA Gridded Data API - 1,500 individual requests per day.
  • For the VAAC London QVA Products API - 500 individual requests per day.

However, it is possible to download all data published for an individual volcano by making only four requests:

  • One request to find out the volcano number from the collections information
  • One request for all deterministic gridded data
  • One request for all probabilistic gridded data
  • One request for all IWXXM data
Service Level Agreement

The VAAC London Manager reports periodically to the UK Civil Aviation Authority (CAA) and International Civil Aviation Organization (ICAO), who oversee the provision of the Quantitative Volcanic Ash service.

VAAC performance is monitored and reported to the ICAO Met Panel International Airways Volcano Watch operations group (METP-WG-MOG-IAVW).

Forecast data itself is verified by the Met Office regularly.

Capacity of Service

The Service was load tested without any loss of performance against 400 unique users, 4 simultaneous volcanic events, and over a 10-minute window.

Availability

The Service has been developed with high availability in mind and is monitored via synthetic canaries. The REST API collection endpoints are monitored against provisioning response payloads advertised as ready for collection.

During a significant volcanic event, qualified end users (duly authorised and authenticated via APIM) must be able to make EDR API requests >99% of the time: 

  • and the relevant API will provision a response payload; 
  • and obtain a HTTP 302 signed redirect URL within 30 seconds or less of their API request; 
  • and download matching payloads for datasets and volcanoes that are advertised as ‘ready for collection’.

Thereafter, and until the VAAC London forecasters decide that volcanic ash no longer represents a hazard to air traffic, the volcanic ash forecasts are updated at 6 hourly intervals and usually aligned to the main synoptic hours of 00UTC, 06UTC, 12UTC and 18UTC.

Recoverability

Technical support is available 24/7, although on a 'best efforts only' basis outside normal working hours (09:00-17:00 GMT Monday to Friday, except Bank Holidays).

In the event of operational issues, the equivalent VAAC Toulouse Quantitative Volcanic Ash API service is available for backup purposes (from December 2025).

Confidentiality

The Service adheres to SWIM Yellow Profile, WS Light - Infrastructure Capabilities Binding requirements.

The system does not store or manage any personal data. Threat analysis confirmed that loss of confidentiality is deemed Low Risk.

Integrity

The Met Office has robust Cyber Security protocols in place. In the unlikely event of a security breach impacting the integrity of the data, the Service will be suspended, and VAAC London would notify users to fail over to VAAC Toulouse equivalent Quantitative Volcanic Ash service until security has been fully restored. 

API

Application Programming Interface.

APIM

API Management - the API management platform used for Authentication and Authorisation that is integrated with the QVA Service. APIM acts as the 'front door' of the QVA APIs for our users.

Collection

A set of forecast data for one or more related meteorological parameters.

Dataset

A set of forecast data nested under a 'collection'.

Deterministic collection

The 'qva_deterministic' forecasts the expected ash concentration as a deterministic gridded forecast for a specific timestep. It includes one dataset. You cannot filter payloads to receive only one threshold.

Datasets are provided for twelve vertical slices of the atmosphere between the ground and 60,000ft (Flight level 600), each 5000ft thick.

Payloads are in netCDF format.

FL

Flight Level.

Gridded data

Gridded data refers to climate data that has been spatially interpolated onto a regular grid, creating a consistent and complete spatial representation of weather or climate variables across a specific region. 

VAAC London QVA Gridded Data API's gridded data covers the entirety of an ash plume resulting from a volcanic eruption in Iceland, however wide the plume extends across the globe.

ICAO

The International Civil Aviation Organisation - It is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation. ICAO develops standards and recommended practices for international aviation to ensure safe, efficient, and orderly global air transport. 

IWXXM

ICAO Meteorological Information Exchange Model (IWXXM) is a standardized format for exchanging meteorological information used in aviation. It's an XML-based model designed to represent aviation weather information, including reports like METAR/SPECI, TAF, SIGMET, and features/objects like ash concentration forecasts in the forms of polygons. IWXXM is part of the broader SWIM (System Wide Information Management) initiative within ICAO, alongside FIXM and AIXM.

IWXXM Collection

The 'qvaci_iwxxm' collection consists of sets of polygons that show the expected ash areas for where ash exceeding the four concentration thresholds (0.2mg/m3, 2mg/m3, 5mg/m3 and 10mg/m3) is expected to occur. It includes one dataset, which provides only the vertical levels where the ash plume is present in the atmospheric layer between FL000 and FL600. 

The IWXXM objects/polygons represent a subset of the gridded data with each spanning the minimum to maximum height for a given threshold. All the data sets are provided covering the period from T+0 hour to T+24 hours at 3-hourly intervals from the time they are issued. In the case of a significant volcanic eruption in Iceland, the IWXXM data will be updated every 6 hours while a significant ash cloud remains.

Payloads are in XML format, as per the IWXXM schema https://schemas.wmo.int/iwxxm/2025-2RC1/WAFSSigWxFC.xsd.  Please note this is currently a release candidate, so it may be subject to further adjustment before it comes into effect in November 2025.

Please note that you cannot filter the IWXXM payloads to receive polygons for only one concentration threshold. The API response will return all the data for a particular forecast timestep.

Model run

A model run is the date and time associated to when an instance of the NAME model is started. London VAAC volcanic ash forecasts are generated by our team of forecasters using an atmospheric transport and dispersion model called NAME. The model represents the expected behaviour of the volcanic ash cloud, the direction and speed of travel as well as processes which act to remove ash from the atmosphere: through precipitation, sedimentation (falling out through gravity) and interaction with the Earth’s surface.

After the initial model run is used to produce the very first volcanic ash forecasts following a significant volcanic event, our forecasting team will update the forecasts every 6 hours, up until the time ash is no longer discernible. 

OGC

Open Geospatial Consortium. OGC is a consortium of experts committed to improving access to geospatial, or location information.

Probabilistic collection

The 'qva_probabilistic' collection forecasts the likelihood of ash concentration exceeding four set thresholds in mg/m3: ≥0.2, ≥2.0, ≥5.0 and ≥10.0. It includes four separate datasets (one per threshold).

Datasets are provided for twelve vertical slices of the atmosphere between the ground and 60,000ft (Flight level 600), each 5000ft thick.

Payloads are in netCDF format.

QVA

Quantitative Volcanic Ash. QVA forecasts provide higher resolution information on the location of ash in the atmosphere than the traditional volcanic ash advisory (VAA) products and unlike the VAA, also include ash concentration information. QVA also offers operators the opportunity to move away from the traditional ‘discernible ash’- based criteria for avoiding ash and instead use certified engine susceptibility volcanic ash exposure thresholds for flight route planning and inflight replanning. Operators with approval and procedures/practices will be able to use QVA information to fly more efficient routes while maintaining safety in accordance with their safety management program.

Timestep

Means “forecast period”. A period of time for which forecast data is given, usually expressed as the number of hours after the model run time, e.g. T+6 means 6 hours after the model run time.

VAAC London

Volcanic Ash Advisory Centre. 

VAAC London is an ICAO designated centre, responsible for issuing advisories for volcanic eruptions originating in Iceland and the north-eastern corner of the North Atlantic. It is operated by the Met Office.

VAAC London is one of 9 Volcanic Ash Advisory Centres worldwide, and has specialist forecasters who produce volcanic ash advisories and guidance products using a combination of volcano data; satellite-based, ground-based and aircraft observations; weather forecast models and dispersion models. The volcanic ash forecasts are provided to the standards and tolerances set by the regulator and ICAO.

The forecasts produced by a VAAC are provided to support the aviation industry.

We provide a reciprocal back-up facility with Toulouse VAAC, operated by Météo-France.

WMO

The World Meteorological Organization is a specialised agency of the United Nations responsible for promoting international cooperation on atmospheric science, climatology, hydrology and geophysics. The WMO is responsible for the IWXXM schematron used for the provision of the volcanic ash polygon data sets.

Information
VAAC London Quantitative Volcanic Ash APIs

The Met Office operates the Quantitative Volcanic Ash APIs in its role as the London Volcanic Ash Advisory Centre (VAAC), covering primarily Iceland and the North Atlantic.

Quantitative Volcanic Ash (QVA) forecasts provide higher resolution information on the location of ash in the atmosphere than the traditional volcanic ash advisory (VAA) products and unlike the VAA, also include ash concentration information. QVA also offers operators the opportunity to move away from the traditional ‘discernible ash’- based criteria for avoiding ash and instead use certified engine susceptibility volcanic ash exposure thresholds for flight route planning and in-flight re-planning.

Operators with approval and procedures/practices will be able to use QVA information to fly more efficient routes while maintaining safety in accordance with their safety management program.

The QVA information service comprises of three data sets at 0.25-degree horizontal resolution:

  • The expected ash concentration as a gridded data set.
  • The probability of the ash exceeding four different concentration thresholds (≥0.2mg/m3, ≥2mg/m3, ≥5mg/m3 and ≥10mg/m3) as a gridded data set.
  • Features/objects in IWXXM format that show the expected ash areas for where ash exceeding the four concentration thresholds (≥0.2mg/m3, ≥2mg/m3, ≥5mg/m3 and ≥10mg/m3) is expected to occur.
Data Structures

Schema language

As per WMO specifications:

  • Metadata payloads are in JSON format.
  • Forecasts payloads are in netCDF for the qva_deterministic and qva_probabilistic collections
  • Forecasts payloads are in IWXXM format for the qvaci_iwxxm collection.

The QVA APIs are EDR compliant.

https://ogcapi.ogc.org/edr/
Security Mechanism

TLS 1.2

The service uses HTTPS over TLS 1.2 to provide integrity and confidentiality.

Service Monitoring for the QVA APIs

The QVA APIs are monitored and integrate automated alerts that reach 24/7 Met Office support teams. However, no consumer visible monitoring capabilities are provided. 



The generation of forecast data are triggered on the successful ingestion of requisite base components (push).

Appropriate logging, monitoring and alerting are in place 24/7.

5-minute Synthetic Canary

A heartbeat service is used to periodically check the status of the Service and determine whether it is available.

Two synthetic canaries monitor the 2x QVA APIs against our >99% availability target. They run every 5 minutes 24/7 and check the availability of the three collections, ensuring that the retrieval of payloads for our 3x collections are successful and timely:

  • qva_deterministic

  • qva_probablilistic

  • qvaci_iwxxm

The synthetic canaries are not designed to check every single payload response. However, they have been selected to provide sufficient indication about the health of the Service and its underlying capabilities, and to orient any required investigation.

HTTP Response Codes

Refer to the API Open API/Swagger documentation for guidance.

EDR Response code and name Code Meaning/Possible reasons Impact and suggested actions
200 (OK)

Description:

The request is successful.

 Expected behaviour, you can access the data.
302 (Found)

Description:

Redirect status response code indicating that the resource requested has been temporarily moved to the URL given by the Location header.

Expected behaviour for retrieving location ID (locId) payloads. Follow this redirect to access your payload.
400 (Bad Request)

Description:

The server cannot or will not process the request due to an apparent client error. For example, a query parameter had an incorrect value

Possible Reasons:

You may have included an invalid value for the parameter query string parameter, or datetime query string parameter with an invalid date time or range outside the available forecasts.

a) Check the error message returned in the API response, and

b) Adjust the parameter reported within the error message as being problematic. e.g. collection ID, location ID (locId), datetime (timestep), etc. 

The API Open API/Swagger documentation should also be consulted if necessary for implementation guidance.
401 (Unauthorized Request)

Description:

The request requires user authentication. The response includes a WWW-Authenticate header field containing a challenge applicable to the requested resource.

Possible Reasons

You may not have included your credentials in the request header or there could be a problem with the user credentials supplied.

You cannot access the data due to invalid authorisation. Please check that your authorisation token is valid and has not expired, and try again.

Please ensure you followed the setup instructions communicated to you by the QVA Manager.
403 (Forbidden)

Description:

The server understood the request, but is refusing to fulfil it. While status code 401 indicates missing or bad authentication, status code 403 indicates that authentication is not the issue, but the client is not authorized to perform the requested operation on the resource.

Possible Reasons:

Your request has been rejected as you do not have the rights to access or view the content.

This error can be returned by an origin due to an application firewall or other reason at the custom origin. 

This error code could be returned if, for example, your token has expired, or if you exceeded the number of requests specified by our Throttling policy limits. Please note that OAuth2 tokens are only valid for one hour. Please refresh your token if it has expired.

Additionally, you may need to make a further request to the /collections/{collectionId}/locations/{locationId} endpoint to obtain another signed URL to access the payload.  
404 (Not Found)

Description:

The requested resource does not exist on the server. For example, a path parameter had an incorrect value.

Possible Reasons:

You have entered an invalid URL, invalid collection name or location ID.

You may be attempting to access a resource that has not yet been published.

You should first check that your request is valid, in case you may have specified an invalid URL.

Please note:

  • If there is no published {collectionId} dataset, the collections/{collectionId} endpoint returns an HTTP 404 response. Call the /collections endpoint to check if there is currently a published dataset.

  • If there is no published {locationId} dataset for a given collection, the /collections/{collectionId}/locations/{locationId} endpoint returns an HTTP 404 response. Call the /collections/{collectionId}/locations endpoint to check if there is currently a published dataset.
500 (Internal Server Error)

Description:

An internal error occurred in the server.

Possible Reasons:

This could indicate that a Lambda function in our own systems returned an execution error.

You cannot access the data. Please try again.

If the error persists, please contact our Support teams.
502 (Bad Gateway)

Description:

This error response means that the server, while working as a gateway to get a response needed to handle the request, got an invalid response.

Possible Reasons:

It could indicate our server could not return the requested object because it couldn't connect to the origin server.

You cannot access the data. Please try again.

If the error persists, please contact our Support teams.
504 (Gateway Timeout)

Description:

While the request appears to be valid, the server failed to complete it in a timely manner.

 You cannot access the data. Please try again. If the error persists, please contact our Support teams.
VAAC London QVA Gridded Data API

The VAAC London QVA Gridded Data API supplies meteorological gridded data in response to tailored API requests.

Data is provided under the remit of the International Civil Aviation Organisation (ICAO) and can be used to support activities related to aviation. Specifically, it enables aviation end users operate more effectively in airspaces affected by volcanic eruptions emanating from Iceland.

This API includes two collections in netCDF format as response payloads:

  • the probabilistic collection forecasts the likelihood of ash concentration exceeding four set thresholds in mg/m3: ≥0.2, ≥2.0, ≥5.0 and ≥10.0. It includes four separate datasets (one per threshold).
  • the deterministic collection forecasts the expected ash concentration as a deterministic gridded forecast for a specific timestep. It includes one dataset.
PROVIDER_SIDE
SYNCHRONOUS_REQUEST_RESPONSE
Operations
HTTP GET

The VAAC London QVA Gridded Data API provides gridded meteorological forecasts in netCDF files in response to tailored API requests.

It also provides end users the ability to request metadata about the meteorological forecast included in the forecasts, returning a response in .JSON format.

Synchronous: Transactions are synchronous.

TI Protocol Method: HTTP GET

Precondition: Consumers must be authenticated and authorised via the Met Office API Management (APIM) Developer portal.

Processing consideration: The service shall provide only the latest available data.

Idempotent
IDEMPOTENT
Operation Message
HTTP GET
GET /collections

This endpoint returns metadata in JSON format about the "qva_probabilistic" and "qva_deterministic" collections that are available to be queried. Metadata includes:

  • Collection "id", "title" and "description"
  • Geospatial information
  • Forecast intervals (timesteps)
  • Vertical atmospheric slices
  • a list of "volcano_id" and associated metadata
Resource Type
REST_RESOURCE
Url

https://gateway.api-management.metoffice.cloud/vaac-london-qva-gridded-…

GET /collections/{collectionId}
  • Get information about the "qva_probabilistic" {collectionId}. Response is a JSON file. It is the ‘source of truth’ to check which data has been generated and is ready to download. This is the endpoint that you can query to find out the applicable "volcano_id" for which forecast data is available. You can then use "volcano_id" to build your API request: https://gateway.api-management.metoffice.cloud/vaac-london-qva-gridded-…
  • Get information about the "qva_deterministic" {collectionId}. Response is a JSON file. It is the ‘source of truth’ to check which data has been generated and is ready to download. This is the endpoint that you can query to find out the applicable "volcano_id" for which forecast data is available. You can then use "volcano_id" to build your API request: https://gateway.api-management.metoffice.cloud/vaac-london-qva-gridded-…

 

Resource Type
REST_RESOURCE
Url

https://gateway.api-management.metoffice.cloud/vaac-london-qva-gridded-…

GET /collections/{collectionId}/locations

This is also the endpoint that you can query to find out the applicable volcano for which forecast data is available. If forecasts are available for multiple volcanic eruptions, then multiple "volcano_id" may be listed.

Response is a JSON file.

Resource Type
REST_RESOURCE
Url

https://gateway.api-management.metoffice.cloud/vaac-london-qva-gridded-…

Get /collections/{collectionId}/locations/{locationId}

This is the endpoint you query to retrieve the volcanic ash forecast in a specific collection {collectionId} for a specific volcano_id {locationId}.

For example, requesting data in the ‘qva_probabilistic’ collection for volcano_id 372070 (Hekla in Iceland): https://gateway.api-management.metoffice.cloud/vaac-london-qva-gridded-data/1.0/collections/qva_probabilistic/locations/372070

For example, requesting data in the ‘qva_probabilistic’ collection for volcano_id 372070 (Hekla in Iceland): https://gateway.api-management.metoffice.cloud/vaac-london-qva-gridded-data/1.0/collections/qva_deterministic/locations/372070 

A successful request for data will return a “302 Found” response code with a redirect link in the Location header of the response, which you can use to download the requested dataset. The link is valid for one hour.

The payload response is in netCDF format. When following the Redirected URL, you will get a 200 response and the requested binary netCDF data, which you can save as an .nc file in your systems.

Resource Type
REST_RESOURCE
Url

https://gateway.api-management.metoffice.cloud/vaac-london-qva-gridded-…

WS Light

The Service Interface Binding is SWIM Yellow Profile Compliant, using WS Light enabling HTTP GET requests and associated responses.

  • The Service shall return a .JSON response for metadata requests:
    • OpenAPI:
      • / gets the EDR root data entrypoint
      • /api gets the EDR spec for exposed endpoints
    • /conformance gets the conformance data for the API
    • Collections data:
      • /collections gets the end point that contains information about all the collections available
      • /collections/{collectionId} gets the end point that contains information about an individual collection {collectionId}
    • Location data: /collections/{collectionId}/locations gets the end point that contains information about the volcanoes for which ash forecast data is available in an individual collection {collectionId}
    •  
  • Request for meteorological forecast data shall return a response as a 302 URL redirect to the payload, either in netCDF or IWXXM format:
    • Ash concentration forecast for a specific Volcano (locationId}: /collections/{collectionId}/locations/{locationId} gets the end point for forecast data for a specific volcano (locationId} contained in an individual collection {collectionId}
IPV4_SECURE_UNICAST

The Service implementation conforms with IPV4_SECURE_UNICAST as part of SWIM Yellow Profile requirements.

VAAC London QVA Products API

The VAAC London QVA Products API supplies spatial polygon data in response to tailored API requests.

Data is provided under the remit of the International Civil Aviation Organisation (ICAO) and can be used to support activities related to aviation. Specifically, it enables aviation end users operate more effectively in airspaces affected by volcanic eruptions emanating from Iceland.

This API includes forecast polygons of volcanic ash, with payloads in XML format as per the IWXXM schema. Data consists of sets of polygons that represent the ash concentration when it exceeds each of the four following four thresholds in mg/m3: ≥0.2, ≥2.0, ≥5.0 and ≥10.0, where the ash plume is present in the atmospheric layer between FL000 and FL600. This collection has one dataset.

PROVIDER_SIDE
SYNCHRONOUS_REQUEST_RESPONSE
Operations
HTTP GET

The VAAC London QVA Products API provides meteorological forecasts as XML files.

It also provides end users the ability to request metadata about the meteorological forecast included in the forecasts, returning a response in .JSON format.

Synchronous: Transactions are synchronous.

TI Protocol Method: HTTP GET

Precondition: Consumers must be authenticated and authorised via the Met Office API Management (APIM) Developer portal.

Processing consideration: The service shall provide only the latest available data.

Idempotent
IDEMPOTENT
Operation Message
HTTP GET
GET /collections/{collectionId}/locations

Get information about all the available locations data (displayed as ‘volcano_id’) in the "qvaci_iwxxm" {collectionId}.

This is also the endpoint that you can query to find out the applicable volcano for which forecast data is available. If forecasts are available for multiple volcanic eruptions, then multiple "volcano_id" may be listed.

Response is a JSON file. 

Resource Type
REST_RESOURCE
Url

https://gateway.api-management.metoffice.cloud/vaac-london-qva-products…

Get /collections/{collectionId}/locations/{locationId}

This is the endpoint you query to retrieve the volcanic ash forecast in the "qvaci_iwxxm" {collectionId} for a specific "volcano_id"/{locationId}.  

Example URL for requesting data in the "qvaci_iwxxm" collection for "volcano_id" 372070 (Hekla in Iceland): https://gateway.api-management.metoffice.cloud/vaac-london-qva-products/1.0/collections/qvaci_iwxxm/locations/372070

A successful request for data will return a “302 Found” response code with a redirect link in the Location header of the response, which you can use to download the requested dataset. The link is valid for one hour.

Response is in XML format. When following the Redirected URL, you will get a 200 response and the requested data, which you can save as an .xml file in your systems.

Resource Type
REST_RESOURCE
Url

https://gateway.api-management.metoffice.cloud/vaac-london-qva-products…

WS Light

The Service Interface Binding is SWIM Yellow Profile Compliant, using WS Light enabling HTTP GET requests and associated responses.

  • The Service shall return a .JSON response for metadata requests:
    • OpenAPI:
      • / gets the EDR root data entrypoint
      • /api gets the EDR spec for exposed endpoints
    • /conformance gets the conformance data for the API
    • Collections data:
      • /collections gets the end point that contains information about all the collections available
      • /collections/{collectionId} gets the end point that contains information about an individual collection {collectionId}
    • Location data: /collections/{collectionId}/locations gets the end point that contains information about the volcanoes for which ash forecast data is available in an individual collection {collectionId}
    •  
  • Request for meteorological forecast data shall return a response as a 302 URL redirect to the payload, either in netCDF or IWXXM format:
    • Ash concentration forecast for a specific Volcano (locationId}: /collections/{collectionId}/locations/{locationId} gets the end point for forecast data for a specific volcano (locationId} contained in an individual collection {collectionId}
IPV4_SECURE_UNICAST

The Service implementation conforms with IPV4_SECURE_UNICAST as part of SWIM Yellow Profile requirements.

References
IWXXM Schema

The downloaded IWXXM data (.xml) will return all the information within a single file. This will adhere to the schema IWXXM Schematrons published here: https://schemas.wmo.int/iwxxm/

Note: up until late November 2025 the 2025-2R1 schematron is used, and when the final candidate version published (version 2025-2) the system will be updated to reflect it. If further changes are made to the schematrons by WMO further updates will be made, potentially coordinated with the other VAAC’s and you will be notified in advance that it will be changing.

Revision Save Date
Thu, 11/27/2025 - 10:55
Schema version
v2