Bureau of Meteorology changing aviation products

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On 10 November 2016, the Bureau of Meteorology will change some of its aviation products to better comply, where practical, with the standards set out by the International Civil Aviation Organization (ICAO). This includes low level area forecasts (ARFORs), SIGMETs and AIRMETs as detailed below.

Vertical extent of an Area Forecast (ARFOR)

Area Forecasts will cover the airspace between the surface and 10,000 feet compared to the current area forecast which covers the airspace from the surface to 20,000 feet. Forecasts above 10,000 feet can be obtained from Medium and High Level Significant Weather (SIGWX) charts, Grid Point Wind and Temperature (GPWT) charts and NAIPS Wind/Temperature Profile.



Changes will be made to Australian SIGMET sequence numbers and the remarks line (RMK) as below:

  • the Australian SIGMET sequence numbers will no longer reset at 0001UTC, and instead the sequence numbering will continue until the SIGMET for the event is cancelled. Should more than 99 SIGMETs be issued for a particular event, the number portion of the sequence number will go from 99 to 02. Sequence number 01 will be reserved for new SIGMETs.
  • the status information (NEW, EXTD, CNL) will be removed from the remark line of Australian SIGMETs as this information can be determined from other sections as follows:
    • NEW – any SIGMET with a sequence number of one, such as X01, will always be a new SIGMET;
    • EXTD – any SIGMET with a sequence number greater than one, such as X02, will be an extension or a cancellation of a current SIGMET; and
    • CNL – Cancel information is contained in the body of the SIGMET


The format of AIRMETs will be changed mostly to align with the ICAO Annex 3 specifications. The new AIRMET will follow a very similar format to the existing SIGMET format. More information is available via the Bureau of Meteorology’s website.

The Bureau’s Aviation Knowledge Centre also has further information on aviation weather products and services, or you can contact webav@bom.gov.au with any questions.


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